Merge commit '258b15c506a2d3ad862fd17ae24eaf272443f477' into sync-from-ra

.cargo/config.toml

@@ -8,4 +8,4 @@ lint = "clippy --all-targets -- -Aclippy::collapsible_if -Aclippy::needless_pass
 linker = "rust-lld"
 
 [env]
-CARGO_WORKSPACE_DIR = { value = "", relative = true }
+CARGO_WORKSPACE_DIR = { value = "", relative = true }

.github/workflows/ci.yaml

@@ -86,12 +86,20 @@ jobs:
       - name: Test
         run: cargo test ${{ env.USE_SYSROOT_ABI }} -- --nocapture --quiet
 
+      - name: Switch to stable toolchain
+        run: |
+          rustup update --no-self-update stable
+          rustup component add --toolchain stable rust-src
+          rustup default stable
+
       - name: Run analysis-stats on rust-analyzer
         if: matrix.os == 'ubuntu-latest'
         run: target/${{ matrix.target }}/debug/rust-analyzer analysis-stats .
 
       - name: Run analysis-stats on rust std library
         if: matrix.os == 'ubuntu-latest'
+        env:
+          RUSTC_BOOTSTRAP: 1
         run: target/${{ matrix.target }}/debug/rust-analyzer analysis-stats --with-deps $(rustc --print sysroot)/lib/rustlib/src/rust/library/std
 
   # Weird targets to catch non-portable code

.github/workflows/metrics.yaml

@@ -67,7 +67,7 @@ jobs:
   other_metrics:
     strategy:
       matrix:
-        names: [self, ripgrep, webrender, diesel]
+        names: [self, ripgrep-13.0.0, webrender-2022, diesel-1.4.8, hyper-0.14.18]
     runs-on: ubuntu-latest
     needs: [setup_cargo, build_metrics]
 
@@ -92,7 +92,7 @@ jobs:
           key: ${{ runner.os }}-target-${{ github.sha }}
 
       - name: Collect metrics
-        run: cargo xtask metrics ${{ matrix.names }}
+        run: cargo xtask metrics "${{ matrix.names }}"
 
       - name: Upload metrics
         uses: actions/upload-artifact@v3
@@ -118,25 +118,30 @@ jobs:
         with:
           name: self-${{ github.sha }}
 
-      - name: Download ripgrep metrics
+      - name: Download ripgrep-13.0.0 metrics
         uses: actions/download-artifact@v3
         with:
-          name: ripgrep-${{ github.sha }}
+          name: ripgrep-13.0.0-${{ github.sha }}
 
-      - name: Download webrender metrics
+      - name: Download webrender-2022 metrics
         uses: actions/download-artifact@v3
         with:
-          name: webrender-${{ github.sha }}
+          name: webrender-2022-${{ github.sha }}
 
-      - name: Download diesel metrics
+      - name: Download diesel-1.4.8 metrics
         uses: actions/download-artifact@v3
         with:
-          name: diesel-${{ github.sha }}
+          name: diesel-1.4.8-${{ github.sha }}
+
+      - name: Download hyper-0.14.18 metrics
+        uses: actions/download-artifact@v3
+        with:
+          name: hyper-0.14.18-${{ github.sha }}
 
       - name: Combine json
         run: |
           git clone --depth 1 https://$METRICS_TOKEN@github.com/rust-analyzer/metrics.git
-          jq -s ".[0] * .[1] * .[2] * .[3] * .[4]" build.json self.json ripgrep.json webrender.json diesel.json -c >> metrics/metrics.json
+          jq -s ".[0] * .[1] * .[2] * .[3] * .[4] * .[5]" build.json self.json ripgrep-13.0.0.json webrender-2022.json diesel-1.4.8.json hyper-0.14.18.json -c >> metrics/metrics.json
           cd metrics
           git add .
           git -c user.name=Bot -c user.email=dummy@example.com commit --message 📈

.github/workflows/release.yaml

@@ -128,6 +128,8 @@ jobs:
 
       - name: Run analysis-stats on rust std library
         if: matrix.target == 'x86_64-unknown-linux-gnu'
+        env:
+          RUSTC_BOOTSTRAP: 1
         run: target/${{ matrix.target }}/release/rust-analyzer analysis-stats --with-deps $(rustc --print sysroot)/lib/rustlib/src/rust/library/std
 
       - name: Upload artifacts

Cargo.lock

@@ -381,14 +381,14 @@ dependencies = [
 
 [[package]]
 name = "filetime"
-version = "0.2.19"
+version = "0.2.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e884668cd0c7480504233e951174ddc3b382f7c2666e3b7310b5c4e7b0c37f9"
+checksum = "d4029edd3e734da6fe05b6cd7bd2960760a616bd2ddd0d59a0124746d6272af0"
 dependencies = [
  "cfg-if",
  "libc",
- "redox_syscall",
+ "redox_syscall 0.3.5",
- "windows-sys 0.42.0",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
@@ -541,6 +541,7 @@ dependencies = [
  "mbe",
  "once_cell",
  "profile",
+ "ra-ap-rustc_parse_format",
  "rustc-hash",
  "smallvec",
  "stdx",
@@ -854,7 +855,6 @@ version = "0.0.0"
 dependencies = [
  "dashmap",
  "hashbrown 0.12.3",
- "once_cell",
  "rustc-hash",
  "triomphe",
 ]
@@ -999,7 +999,7 @@ checksum = "b06a4cde4c0f271a446782e3eff8de789548ce57dbc8eca9292c27f4a42004b4"
 
 [[package]]
 name = "lsp-server"
-version = "0.7.3"
+version = "0.7.4"
 dependencies = [
  "crossbeam-channel",
  "log",
@@ -1010,9 +1010,9 @@ dependencies = [
 
 [[package]]
 name = "lsp-server"
-version = "0.7.3"
+version = "0.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "72417faa455bfb4e5bf14b157d8e2ca2ed74b4e89b8cf42ea2d864825ae5c8a2"
+checksum = "b52dccdf3302eefab8c8a1273047f0a3c3dca4b527c8458d00c09484c8371928"
 dependencies = [
  "crossbeam-channel",
  "log",
@@ -1149,20 +1149,21 @@ checksum = "2bf50223579dc7cdcfb3bfcacf7069ff68243f8c363f62ffa99cf000a6b9c451"
 
 [[package]]
 name = "notify"
-version = "5.1.0"
+version = "6.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "58ea850aa68a06e48fdb069c0ec44d0d64c8dbffa49bf3b6f7f0a901fdea1ba9"
+checksum = "6205bd8bb1e454ad2e27422015fb5e4f2bcc7e08fa8f27058670d208324a4d2d"
 dependencies = [
- "bitflags 1.3.2",
+ "bitflags 2.3.2",
  "crossbeam-channel",
  "filetime",
  "fsevent-sys",
  "inotify",
  "kqueue",
  "libc",
+ "log",
  "mio",
  "walkdir",
- "windows-sys 0.42.0",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
@@ -1251,7 +1252,7 @@ dependencies = [
  "cfg-if",
  "instant",
  "libc",
- "redox_syscall",
+ "redox_syscall 0.2.16",
  "smallvec",
  "winapi",
 ]
@@ -1264,7 +1265,7 @@ checksum = "ba1ef8814b5c993410bb3adfad7a5ed269563e4a2f90c41f5d85be7fb47133bf"
 dependencies = [
  "cfg-if",
  "libc",
- "redox_syscall",
+ "redox_syscall 0.2.16",
  "smallvec",
  "windows-sys 0.42.0",
 ]
@@ -1482,15 +1483,35 @@ dependencies = [
 ]
 
 [[package]]
-name = "ra-ap-rustc_lexer"
+name = "ra-ap-rustc_index"
-version = "0.1.0"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e1c145702ed3f237918e512685185dc8a4d0edc3a5326c63d20361d8ba9b45b3"
+checksum = "07b5fa61d34da18e148dc3a81f654488ea07f40938d8aefb17f8b64bb78c6120"
 dependencies = [
- "unic-emoji-char",
+ "arrayvec",
+ "smallvec",
+]
+
+[[package]]
+name = "ra-ap-rustc_lexer"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2e2f6b48422e4eed5218277ab7cc9733e60dd8f3167f4f36a49a0cafe4dc195"
+dependencies = [
+ "unicode-properties",
  "unicode-xid",
 ]
 
+[[package]]
+name = "ra-ap-rustc_parse_format"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3c7369ad01cc79f9e3513c9f6a6326f6b980100e4862a7ac71b9991c88108bb"
+dependencies = [
+ "ra-ap-rustc_index",
+ "ra-ap-rustc_lexer",
+]
+
 [[package]]
 name = "rayon"
 version = "1.7.0"
@@ -1522,6 +1543,15 @@ dependencies = [
  "bitflags 1.3.2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "567664f262709473930a4bf9e51bf2ebf3348f2e748ccc50dea20646858f8f29"
+dependencies = [
+ "bitflags 1.3.2",
+]
+
 [[package]]
 name = "rowan"
 version = "0.15.11"
@@ -1545,7 +1575,6 @@ dependencies = [
  "crossbeam-channel",
  "dissimilar",
  "expect-test",
- "filetime",
  "flycheck",
  "hir",
  "hir-def",
@@ -1555,7 +1584,7 @@ dependencies = [
  "ide-ssr",
  "itertools",
  "load-cargo",
- "lsp-server 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lsp-server 0.7.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "lsp-types",
  "mbe",
  "mimalloc",
@@ -2056,47 +2085,6 @@ version = "1.16.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a3e5df347f0bf3ec1d670aad6ca5c6a1859cd9ea61d2113125794654ccced68f"
 
-[[package]]
-name = "unic-char-property"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a8c57a407d9b6fa02b4795eb81c5b6652060a15a7903ea981f3d723e6c0be221"
-dependencies = [
- "unic-char-range",
-]
-
-[[package]]
-name = "unic-char-range"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0398022d5f700414f6b899e10b8348231abf9173fa93144cbc1a43b9793c1fbc"
-
-[[package]]
-name = "unic-common"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "80d7ff825a6a654ee85a63e80f92f054f904f21e7d12da4e22f9834a4aaa35bc"
-
-[[package]]
-name = "unic-emoji-char"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b07221e68897210270a38bde4babb655869637af0f69407f96053a34f76494d"
-dependencies = [
- "unic-char-property",
- "unic-char-range",
- "unic-ucd-version",
-]
-
-[[package]]
-name = "unic-ucd-version"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "96bd2f2237fe450fcd0a1d2f5f4e91711124f7857ba2e964247776ebeeb7b0c4"
-dependencies = [
- "unic-common",
-]
-
 [[package]]
 name = "unicase"
 version = "2.6.0"
@@ -2127,6 +2115,12 @@ dependencies = [
  "tinyvec",
 ]
 
+[[package]]
+name = "unicode-properties"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7f91c8b21fbbaa18853c3d0801c78f4fc94cdb976699bb03e832e75f7fd22f0"
+
 [[package]]
 name = "unicode-segmentation"
 version = "1.10.1"

Cargo.toml

@@ -86,7 +86,7 @@ proc-macro-test = { path = "./crates/proc-macro-test" }
 # In-tree crates that are published separately and follow semver. See lib/README.md
 line-index = { version = "0.1.0-pre.1" }
 la-arena = { version = "0.3.1" }
-lsp-server = { version = "0.7.3" }
+lsp-server = { version = "0.7.4" }
 
 # non-local crates
 smallvec = { version = "1.10.0", features = [
@@ -97,11 +97,15 @@ smallvec = { version = "1.10.0", features = [
 smol_str = "0.2.0"
 nohash-hasher = "0.2.0"
 text-size = "1.1.0"
-# See https://github.com/serde-rs/serde/issues/2538#issuecomment-1684517372 for why we pin serde
+serde = { version = "1.0.156", features = ["derive"] }
-serde = { version = "1.0.156, < 1.0.172", features = ["derive"] }
 serde_json = "1.0.96"
 triomphe = { version = "0.1.8", default-features = false, features = ["std"] }
 # can't upgrade due to dashmap depending on 0.12.3 currently
 hashbrown = { version = "0.12.3", features = ["inline-more"], default-features = false }
 
-rustc_lexer = { version = "0.1.0", package = "ra-ap-rustc_lexer" }
+rustc_lexer = { version = "0.10.0", package = "ra-ap-rustc_lexer" }
+rustc_parse_format = { version = "0.10.0", package = "ra-ap-rustc_parse_format", default-features = false }
+
+# Upstream broke this for us so we can't update it
+rustc_abi = { version = "0.0.20221221", package = "hkalbasi-rustc-ap-rustc_abi", default-features = false }
+rustc_index = { version = "0.0.20221221", package = "hkalbasi-rustc-ap-rustc_index", default-features = false }

crates/base-db/src/fixture.rs

@@ -179,8 +179,8 @@ impl ChangeFixture {
                     meta.edition,
                     Some(crate_name.clone().into()),
                     version,
-                    meta.cfg,
+                    meta.cfg.clone(),
-                    Default::default(),
+                    Some(meta.cfg),
                     meta.env,
                     false,
                     origin,
@@ -200,7 +200,7 @@ impl ChangeFixture {
             } else if meta.path == "/main.rs" || meta.path == "/lib.rs" {
                 assert!(default_crate_root.is_none());
                 default_crate_root = Some(file_id);
-                default_cfg = meta.cfg;
+                default_cfg.extend(meta.cfg.into_iter());
                 default_env.extend(meta.env.iter().map(|(x, y)| (x.to_owned(), y.to_owned())));
                 default_target_data_layout = meta.target_data_layout;
             }
@@ -220,8 +220,8 @@ impl ChangeFixture {
                 Edition::CURRENT,
                 Some(CrateName::new("test").unwrap().into()),
                 None,
-                default_cfg,
+                default_cfg.clone(),
-                Default::default(),
+                Some(default_cfg),
                 default_env,
                 false,
                 CrateOrigin::Local { repo: None, name: None },

crates/cfg/src/lib.rs

@@ -86,6 +86,32 @@ impl CfgOptions {
     }
 }
 
+impl Extend<CfgAtom> for CfgOptions {
+    fn extend<T: IntoIterator<Item = CfgAtom>>(&mut self, iter: T) {
+        iter.into_iter().for_each(|cfg_flag| _ = self.enabled.insert(cfg_flag));
+    }
+}
+
+impl IntoIterator for CfgOptions {
+    type Item = <FxHashSet<CfgAtom> as IntoIterator>::Item;
+
+    type IntoIter = <FxHashSet<CfgAtom> as IntoIterator>::IntoIter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        <FxHashSet<CfgAtom> as IntoIterator>::into_iter(self.enabled)
+    }
+}
+
+impl<'a> IntoIterator for &'a CfgOptions {
+    type Item = <&'a FxHashSet<CfgAtom> as IntoIterator>::Item;
+
+    type IntoIter = <&'a FxHashSet<CfgAtom> as IntoIterator>::IntoIter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        <&FxHashSet<CfgAtom> as IntoIterator>::into_iter(&self.enabled)
+    }
+}
+
 #[derive(Default, Clone, Debug, PartialEq, Eq)]
 pub struct CfgDiff {
     // Invariants: No duplicates, no atom that's both in `enable` and `disable`.

crates/flycheck/src/lib.rs

@@ -5,7 +5,9 @@
 #![warn(rust_2018_idioms, unused_lifetimes, semicolon_in_expressions_from_macros)]
 
 use std::{
+    ffi::OsString,
     fmt, io,
+    path::PathBuf,
     process::{ChildStderr, ChildStdout, Command, Stdio},
     time::Duration,
 };
@@ -168,7 +170,7 @@ struct FlycheckActor {
     /// doesn't provide a way to read sub-process output without blocking, so we
     /// have to wrap sub-processes output handling in a thread and pass messages
     /// back over a channel.
-    cargo_handle: Option<CargoHandle>,
+    command_handle: Option<CommandHandle>,
 }
 
 enum Event {
@@ -184,7 +186,7 @@ impl FlycheckActor {
         workspace_root: AbsPathBuf,
     ) -> FlycheckActor {
         tracing::info!(%id, ?workspace_root, "Spawning flycheck");
-        FlycheckActor { id, sender, config, root: workspace_root, cargo_handle: None }
+        FlycheckActor { id, sender, config, root: workspace_root, command_handle: None }
     }
 
     fn report_progress(&self, progress: Progress) {
@@ -192,7 +194,7 @@ impl FlycheckActor {
     }
 
     fn next_event(&self, inbox: &Receiver<StateChange>) -> Option<Event> {
-        let check_chan = self.cargo_handle.as_ref().map(|cargo| &cargo.receiver);
+        let check_chan = self.command_handle.as_ref().map(|cargo| &cargo.receiver);
         if let Ok(msg) = inbox.try_recv() {
             // give restarts a preference so check outputs don't block a restart or stop
             return Some(Event::RequestStateChange(msg));
@@ -221,21 +223,19 @@ impl FlycheckActor {
                     }
 
                     let command = self.check_command();
+                    let formatted_command = format!("{:?}", command);
+
                     tracing::debug!(?command, "will restart flycheck");
-                    match CargoHandle::spawn(command) {
+                    match CommandHandle::spawn(command) {
-                        Ok(cargo_handle) => {
+                        Ok(command_handle) => {
-                            tracing::debug!(
+                            tracing::debug!(command = formatted_command, "did  restart flycheck");
-                                command = ?self.check_command(),
+                            self.command_handle = Some(command_handle);
-                                "did  restart flycheck"
-                            );
-                            self.cargo_handle = Some(cargo_handle);
                             self.report_progress(Progress::DidStart);
                         }
                         Err(error) => {
                             self.report_progress(Progress::DidFailToRestart(format!(
-                                "Failed to run the following command: {:?} error={}",
+                                "Failed to run the following command: {} error={}",
-                                self.check_command(),
+                                formatted_command, error
-                                error
                             )));
                         }
                     }
@@ -244,12 +244,14 @@ impl FlycheckActor {
                     tracing::debug!(flycheck_id = self.id, "flycheck finished");
 
                     // Watcher finished
-                    let cargo_handle = self.cargo_handle.take().unwrap();
+                    let command_handle = self.command_handle.take().unwrap();
-                    let res = cargo_handle.join();
+                    let formatted_handle = format!("{:?}", command_handle);
+
+                    let res = command_handle.join();
                     if res.is_err() {
                         tracing::error!(
-                            "Flycheck failed to run the following command: {:?}",
+                            "Flycheck failed to run the following command: {}",
-                            self.check_command()
+                            formatted_handle
                         );
                     }
                     self.report_progress(Progress::DidFinish(res));
@@ -284,12 +286,12 @@ impl FlycheckActor {
     }
 
     fn cancel_check_process(&mut self) {
-        if let Some(cargo_handle) = self.cargo_handle.take() {
+        if let Some(command_handle) = self.command_handle.take() {
             tracing::debug!(
-                command = ?self.check_command(),
+                command = ?command_handle,
                 "did  cancel flycheck"
             );
-            cargo_handle.cancel();
+            command_handle.cancel();
             self.report_progress(Progress::DidCancel);
         }
     }
@@ -391,19 +393,36 @@ impl Drop for JodGroupChild {
 }
 
 /// A handle to a cargo process used for fly-checking.
-struct CargoHandle {
+struct CommandHandle {
     /// The handle to the actual cargo process. As we cannot cancel directly from with
     /// a read syscall dropping and therefore terminating the process is our best option.
     child: JodGroupChild,
     thread: stdx::thread::JoinHandle<io::Result<(bool, String)>>,
     receiver: Receiver<CargoMessage>,
+    program: OsString,
+    arguments: Vec<OsString>,
+    current_dir: Option<PathBuf>,
 }
 
-impl CargoHandle {
+impl fmt::Debug for CommandHandle {
-    fn spawn(mut command: Command) -> std::io::Result<CargoHandle> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("CommandHandle")
+            .field("program", &self.program)
+            .field("arguments", &self.arguments)
+            .field("current_dir", &self.current_dir)
+            .finish()
+    }
+}
+
+impl CommandHandle {
+    fn spawn(mut command: Command) -> std::io::Result<CommandHandle> {
         command.stdout(Stdio::piped()).stderr(Stdio::piped()).stdin(Stdio::null());
         let mut child = command.group_spawn().map(JodGroupChild)?;
 
+        let program = command.get_program().into();
+        let arguments = command.get_args().map(|arg| arg.into()).collect::<Vec<OsString>>();
+        let current_dir = command.get_current_dir().map(|arg| arg.to_path_buf());
+
         let stdout = child.0.inner().stdout.take().unwrap();
         let stderr = child.0.inner().stderr.take().unwrap();
 
@@ -413,7 +432,7 @@ impl CargoHandle {
             .name("CargoHandle".to_owned())
             .spawn(move || actor.run())
             .expect("failed to spawn thread");
-        Ok(CargoHandle { child, thread, receiver })
+        Ok(CommandHandle { program, arguments, current_dir, child, thread, receiver })
     }
 
     fn cancel(mut self) {

crates/hir-def/Cargo.toml

@@ -31,8 +31,10 @@ smallvec.workspace = true
 hashbrown.workspace = true
 triomphe.workspace = true
 
-rustc_abi = { version = "0.0.20221221", package = "hkalbasi-rustc-ap-rustc_abi", default-features = false }
+rustc_abi.workspace = true
-rustc_index = { version = "0.0.20221221", package = "hkalbasi-rustc-ap-rustc_index", default-features = false }
+rustc_index.workspace = true
+rustc_parse_format.workspace = true
+
 
 # local deps
 stdx.workspace = true

crates/hir-def/src/attr.rs

@@ -5,7 +5,7 @@ pub mod builtin;
 #[cfg(test)]
 mod tests;
 
-use std::{hash::Hash, ops};
+use std::{hash::Hash, ops, slice::Iter as SliceIter};
 
 use base_db::CrateId;
 use cfg::{CfgExpr, CfgOptions};
@@ -14,12 +14,11 @@ use hir_expand::{
     attrs::{collect_attrs, Attr, AttrId, RawAttrs},
     HirFileId, InFile,
 };
-use itertools::Itertools;
 use la_arena::{ArenaMap, Idx, RawIdx};
 use mbe::DelimiterKind;
 use syntax::{
-    ast::{self, HasAttrs, IsString},
+    ast::{self, HasAttrs},
-    AstPtr, AstToken, SmolStr, TextRange, TextSize,
+    AstPtr, SmolStr,
 };
 use triomphe::Arc;
 
@@ -33,26 +32,6 @@ use crate::{
     LocalFieldId, Lookup, MacroId, VariantId,
 };
 
-/// Holds documentation
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct Documentation(String);
-
-impl Documentation {
-    pub fn new(s: String) -> Self {
-        Documentation(s)
-    }
-
-    pub fn as_str(&self) -> &str {
-        &self.0
-    }
-}
-
-impl From<Documentation> for String {
-    fn from(Documentation(string): Documentation) -> Self {
-        string
-    }
-}
-
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
 pub struct Attrs(RawAttrs);
 
@@ -221,33 +200,6 @@ impl Attrs {
         self.by_key("lang").string_value().and_then(|it| LangItem::from_str(it))
     }
 
-    pub fn docs(&self) -> Option<Documentation> {
-        let docs = self.by_key("doc").attrs().filter_map(|attr| attr.string_value());
-        let indent = doc_indent(self);
-        let mut buf = String::new();
-        for doc in docs {
-            // str::lines doesn't yield anything for the empty string
-            if !doc.is_empty() {
-                buf.extend(Itertools::intersperse(
-                    doc.lines().map(|line| {
-                        line.char_indices()
-                            .nth(indent)
-                            .map_or(line, |(offset, _)| &line[offset..])
-                            .trim_end()
-                    }),
-                    "\n",
-                ));
-            }
-            buf.push('\n');
-        }
-        buf.pop();
-        if buf.is_empty() {
-            None
-        } else {
-            Some(Documentation(buf))
-        }
-    }
-
     pub fn has_doc_hidden(&self) -> bool {
         self.by_key("doc").tt_values().any(|tt| {
             tt.delimiter.kind == DelimiterKind::Parenthesis &&
@@ -299,7 +251,6 @@ impl Attrs {
     }
 }
 
-use std::slice::Iter as SliceIter;
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
 pub enum DocAtom {
     /// eg. `#[doc(hidden)]`
@@ -313,7 +264,6 @@ pub enum DocAtom {
 
 // Adapted from `CfgExpr` parsing code
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-// #[cfg_attr(test, derive(derive_arbitrary::Arbitrary))]
 pub enum DocExpr {
     Invalid,
     /// eg. `#[doc(hidden)]`, `#[doc(alias = "x")]`
@@ -574,62 +524,6 @@ impl AttrsWithOwner {
 
         AttrSourceMap::new(owner.as_ref().map(|node| node as &dyn HasAttrs))
     }
-
-    pub fn docs_with_rangemap(
-        &self,
-        db: &dyn DefDatabase,
-    ) -> Option<(Documentation, DocsRangeMap)> {
-        let docs =
-            self.by_key("doc").attrs().filter_map(|attr| attr.string_value().map(|s| (s, attr.id)));
-        let indent = doc_indent(self);
-        let mut buf = String::new();
-        let mut mapping = Vec::new();
-        for (doc, idx) in docs {
-            if !doc.is_empty() {
-                let mut base_offset = 0;
-                for raw_line in doc.split('\n') {
-                    let line = raw_line.trim_end();
-                    let line_len = line.len();
-                    let (offset, line) = match line.char_indices().nth(indent) {
-                        Some((offset, _)) => (offset, &line[offset..]),
-                        None => (0, line),
-                    };
-                    let buf_offset = buf.len();
-                    buf.push_str(line);
-                    mapping.push((
-                        TextRange::new(buf_offset.try_into().ok()?, buf.len().try_into().ok()?),
-                        idx,
-                        TextRange::at(
-                            (base_offset + offset).try_into().ok()?,
-                            line_len.try_into().ok()?,
-                        ),
-                    ));
-                    buf.push('\n');
-                    base_offset += raw_line.len() + 1;
-                }
-            } else {
-                buf.push('\n');
-            }
-        }
-        buf.pop();
-        if buf.is_empty() {
-            None
-        } else {
-            Some((Documentation(buf), DocsRangeMap { mapping, source_map: self.source_map(db) }))
-        }
-    }
-}
-
-fn doc_indent(attrs: &Attrs) -> usize {
-    attrs
-        .by_key("doc")
-        .attrs()
-        .filter_map(|attr| attr.string_value())
-        .flat_map(|s| s.lines())
-        .filter(|line| !line.chars().all(|c| c.is_whitespace()))
-        .map(|line| line.chars().take_while(|c| c.is_whitespace()).count())
-        .min()
-        .unwrap_or(0)
 }
 
 #[derive(Debug)]
@@ -673,7 +567,7 @@ impl AttrSourceMap {
         self.source_of_id(attr.id)
     }
 
-    fn source_of_id(&self, id: AttrId) -> InFile<&Either<ast::Attr, ast::Comment>> {
+    pub fn source_of_id(&self, id: AttrId) -> InFile<&Either<ast::Attr, ast::Comment>> {
         let ast_idx = id.ast_index();
         let file_id = match self.mod_def_site_file_id {
             Some((file_id, def_site_cut)) if def_site_cut <= ast_idx => file_id,
@@ -687,69 +581,6 @@ impl AttrSourceMap {
     }
 }
 
-/// A struct to map text ranges from [`Documentation`] back to TextRanges in the syntax tree.
-#[derive(Debug)]
-pub struct DocsRangeMap {
-    source_map: AttrSourceMap,
-    // (docstring-line-range, attr_index, attr-string-range)
-    // a mapping from the text range of a line of the [`Documentation`] to the attribute index and
-    // the original (untrimmed) syntax doc line
-    mapping: Vec<(TextRange, AttrId, TextRange)>,
-}
-
-impl DocsRangeMap {
-    /// Maps a [`TextRange`] relative to the documentation string back to its AST range
-    pub fn map(&self, range: TextRange) -> Option<InFile<TextRange>> {
-        let found = self.mapping.binary_search_by(|(probe, ..)| probe.ordering(range)).ok()?;
-        let (line_docs_range, idx, original_line_src_range) = self.mapping[found];
-        if !line_docs_range.contains_range(range) {
-            return None;
-        }
-
-        let relative_range = range - line_docs_range.start();
-
-        let InFile { file_id, value: source } = self.source_map.source_of_id(idx);
-        match source {
-            Either::Left(attr) => {
-                let string = get_doc_string_in_attr(attr)?;
-                let text_range = string.open_quote_text_range()?;
-                let range = TextRange::at(
-                    text_range.end() + original_line_src_range.start() + relative_range.start(),
-                    string.syntax().text_range().len().min(range.len()),
-                );
-                Some(InFile { file_id, value: range })
-            }
-            Either::Right(comment) => {
-                let text_range = comment.syntax().text_range();
-                let range = TextRange::at(
-                    text_range.start()
-                        + TextSize::try_from(comment.prefix().len()).ok()?
-                        + original_line_src_range.start()
-                        + relative_range.start(),
-                    text_range.len().min(range.len()),
-                );
-                Some(InFile { file_id, value: range })
-            }
-        }
-    }
-}
-
-fn get_doc_string_in_attr(it: &ast::Attr) -> Option<ast::String> {
-    match it.expr() {
-        // #[doc = lit]
-        Some(ast::Expr::Literal(lit)) => match lit.kind() {
-            ast::LiteralKind::String(it) => Some(it),
-            _ => None,
-        },
-        // #[cfg_attr(..., doc = "", ...)]
-        None => {
-            // FIXME: See highlight injection for what to do here
-            None
-        }
-        _ => None,
-    }
-}
-
 #[derive(Debug, Clone, Copy)]
 pub struct AttrQuery<'attr> {
     attrs: &'attr Attrs,

crates/hir-def/src/attr/builtin.rs

@@ -8,7 +8,8 @@
 //! name resolution, and `BUILTIN_ATTRIBUTES` is almost entirely unchanged from the original, to
 //! ease updating.
 
-use once_cell::sync::OnceCell;
+use std::sync::OnceLock;
+
 use rustc_hash::FxHashMap;
 
 /// Ignored attribute namespaces used by tools.
@@ -29,7 +30,7 @@ pub struct AttributeTemplate {
 }
 
 pub fn find_builtin_attr_idx(name: &str) -> Option<usize> {
-    static BUILTIN_LOOKUP_TABLE: OnceCell<FxHashMap<&'static str, usize>> = OnceCell::new();
+    static BUILTIN_LOOKUP_TABLE: OnceLock<FxHashMap<&'static str, usize>> = OnceLock::new();
     BUILTIN_LOOKUP_TABLE
         .get_or_init(|| {
             INERT_ATTRIBUTES.iter().map(|attr| attr.name).enumerate().map(|(a, b)| (b, a)).collect()

crates/hir-def/src/body.rs

@@ -65,6 +65,8 @@ pub type LabelSource = InFile<LabelPtr>;
 
 pub type FieldPtr = AstPtr<ast::RecordExprField>;
 pub type FieldSource = InFile<FieldPtr>;
+pub type PatFieldPtr = AstPtr<ast::RecordPatField>;
+pub type PatFieldSource = InFile<PatFieldPtr>;
 
 /// An item body together with the mapping from syntax nodes to HIR expression
 /// IDs. This is needed to go from e.g. a position in a file to the HIR
@@ -90,8 +92,8 @@ pub struct BodySourceMap {
 
     /// We don't create explicit nodes for record fields (`S { record_field: 92 }`).
     /// Instead, we use id of expression (`92`) to identify the field.
-    field_map: FxHashMap<FieldSource, ExprId>,
     field_map_back: FxHashMap<ExprId, FieldSource>,
+    pat_field_map_back: FxHashMap<PatId, PatFieldSource>,
 
     expansions: FxHashMap<InFile<AstPtr<ast::MacroCall>>, HirFileId>,
 
@@ -164,9 +166,10 @@ impl Body {
         };
         let module = def.module(db);
         let expander = Expander::new(db, file_id, module);
-        let (mut body, source_map) =
+        let (mut body, mut source_map) =
             Body::new(db, def, expander, params, body, module.krate, is_async_fn);
         body.shrink_to_fit();
+        source_map.shrink_to_fit();
 
         (Arc::new(body), Arc::new(source_map))
     }
@@ -375,9 +378,8 @@ impl BodySourceMap {
         self.field_map_back[&expr].clone()
     }
 
-    pub fn node_field(&self, node: InFile<&ast::RecordExprField>) -> Option<ExprId> {
+    pub fn pat_field_syntax(&self, pat: PatId) -> PatFieldSource {
-        let src = node.map(AstPtr::new);
+        self.pat_field_map_back[&pat].clone()
-        self.field_map.get(&src).cloned()
     }
 
     pub fn macro_expansion_expr(&self, node: InFile<&ast::MacroExpr>) -> Option<ExprId> {
@@ -389,4 +391,29 @@ impl BodySourceMap {
     pub fn diagnostics(&self) -> &[BodyDiagnostic] {
         &self.diagnostics
     }
+
+    fn shrink_to_fit(&mut self) {
+        let Self {
+            expr_map,
+            expr_map_back,
+            pat_map,
+            pat_map_back,
+            label_map,
+            label_map_back,
+            field_map_back,
+            pat_field_map_back,
+            expansions,
+            diagnostics,
+        } = self;
+        expr_map.shrink_to_fit();
+        expr_map_back.shrink_to_fit();
+        pat_map.shrink_to_fit();
+        pat_map_back.shrink_to_fit();
+        label_map.shrink_to_fit();
+        label_map_back.shrink_to_fit();
+        field_map_back.shrink_to_fit();
+        pat_field_map_back.shrink_to_fit();
+        expansions.shrink_to_fit();
+        diagnostics.shrink_to_fit();
+    }
 }

crates/hir-def/src/body/lower.rs

@@ -25,13 +25,20 @@ use triomphe::Arc;
 
 use crate::{
     body::{Body, BodyDiagnostic, BodySourceMap, ExprPtr, LabelPtr, PatPtr},
+    builtin_type::BuiltinUint,
     data::adt::StructKind,
     db::DefDatabase,
     expander::Expander,
     hir::{
-        dummy_expr_id, Array, Binding, BindingAnnotation, BindingId, BindingProblems, CaptureBy,
+        dummy_expr_id,
-        ClosureKind, Expr, ExprId, Label, LabelId, Literal, LiteralOrConst, MatchArm, Movability,
+        format_args::{
-        Pat, PatId, RecordFieldPat, RecordLitField, Statement,
+            self, FormatAlignment, FormatArgs, FormatArgsPiece, FormatArgument, FormatArgumentKind,
+            FormatArgumentsCollector, FormatCount, FormatDebugHex, FormatOptions,
+            FormatPlaceholder, FormatSign, FormatTrait,
+        },
+        Array, Binding, BindingAnnotation, BindingId, BindingProblems, CaptureBy, ClosureKind,
+        Expr, ExprId, InlineAsm, Label, LabelId, Literal, LiteralOrConst, MatchArm, Movability,
+        OffsetOf, Pat, PatId, RecordFieldPat, RecordLitField, Statement,
     },
     item_scope::BuiltinShadowMode,
     lang_item::LangItem,
@@ -42,6 +49,8 @@ use crate::{
     AdtId, BlockId, BlockLoc, ConstBlockLoc, DefWithBodyId, ModuleDefId, UnresolvedMacro,
 };
 
+type FxIndexSet<K> = indexmap::IndexSet<K, std::hash::BuildHasherDefault<rustc_hash::FxHasher>>;
+
 pub(super) fn lower(
     db: &dyn DefDatabase,
     owner: DefWithBodyId,
@@ -437,7 +446,6 @@ impl ExprCollector<'_> {
                                 None => self.missing_expr(),
                             };
                             let src = self.expander.to_source(AstPtr::new(&field));
-                            self.source_map.field_map.insert(src.clone(), expr);
                             self.source_map.field_map_back.insert(expr, src);
                             Some(RecordLitField { name, expr })
                         })
@@ -579,11 +587,6 @@ impl ExprCollector<'_> {
                     syntax_ptr,
                 )
             }
-            ast::Expr::BoxExpr(e) => {
-                let expr = self.collect_expr_opt(e.expr());
-                self.alloc_expr(Expr::Box { expr }, syntax_ptr)
-            }
-
             ast::Expr::ArrayExpr(e) => {
                 let kind = e.kind();
 
@@ -653,6 +656,16 @@ impl ExprCollector<'_> {
                 }
             }
             ast::Expr::UnderscoreExpr(_) => self.alloc_expr(Expr::Underscore, syntax_ptr),
+            ast::Expr::AsmExpr(e) => {
+                let e = self.collect_expr_opt(e.expr());
+                self.alloc_expr(Expr::InlineAsm(InlineAsm { e }), syntax_ptr)
+            }
+            ast::Expr::OffsetOfExpr(e) => {
+                let container = Interned::new(TypeRef::from_ast_opt(&self.ctx(), e.ty()));
+                let fields = e.fields().map(|it| it.as_name()).collect();
+                self.alloc_expr(Expr::OffsetOf(OffsetOf { container, fields }), syntax_ptr)
+            }
+            ast::Expr::FormatArgsExpr(f) => self.collect_format_args(f, syntax_ptr),
         })
     }
 
@@ -663,6 +676,7 @@ impl ExprCollector<'_> {
         let result_expr_id = self.alloc_expr(Expr::Missing, syntax_ptr);
         let prev_binding_owner = self.current_binding_owner.take();
         self.current_binding_owner = Some(result_expr_id);
+
         (result_expr_id, prev_binding_owner)
     }
 
@@ -744,7 +758,27 @@ impl ExprCollector<'_> {
     fn collect_while_loop(&mut self, syntax_ptr: AstPtr<ast::Expr>, e: ast::WhileExpr) -> ExprId {
         let label = e.label().map(|label| self.collect_label(label));
         let body = self.collect_labelled_block_opt(label, e.loop_body());
-        let condition = self.collect_expr_opt(e.condition());
+
+        // Labels can also be used in the condition expression, like this:
+        // ```
+        // fn main() {
+        //     let mut optional = Some(0);
+        //     'my_label: while let Some(a) = match optional {
+        //         None => break 'my_label,
+        //         Some(val) => Some(val),
+        //     } {
+        //         println!("{}", a);
+        //         optional = None;
+        //     }
+        // }
+        // ```
+        let condition = match label {
+            Some(label) => {
+                self.with_labeled_rib(label, |this| this.collect_expr_opt(e.condition()))
+            }
+            None => self.collect_expr_opt(e.condition()),
+        };
+
         let break_expr =
             self.alloc_expr(Expr::Break { expr: None, label: None }, syntax_ptr.clone());
         let if_expr = self.alloc_expr(
@@ -1295,23 +1329,21 @@ impl ExprCollector<'_> {
             ast::Pat::RecordPat(p) => {
                 let path =
                     p.path().and_then(|path| self.expander.parse_path(self.db, path)).map(Box::new);
-                let args = p
+                let record_pat_field_list =
-                    .record_pat_field_list()
+                    &p.record_pat_field_list().expect("every struct should have a field list");
-                    .expect("every struct should have a field list")
+                let args = record_pat_field_list
                     .fields()
                     .filter_map(|f| {
                         let ast_pat = f.pat()?;
                         let pat = self.collect_pat(ast_pat, binding_list);
                         let name = f.field_name()?.as_name();
+                        let src = self.expander.to_source(AstPtr::new(&f));
+                        self.source_map.pat_field_map_back.insert(pat, src);
                         Some(RecordFieldPat { name, pat })
                     })
                     .collect();
 
-                let ellipsis = p
+                let ellipsis = record_pat_field_list.rest_pat().is_some();
-                    .record_pat_field_list()
-                    .expect("every struct should have a field list")
-                    .rest_pat()
-                    .is_some();
 
                 Pat::Record { path, args, ellipsis }
             }
@@ -1531,6 +1563,401 @@ impl ExprCollector<'_> {
         }
     }
     // endregion: labels
+
+    // region: format
+    fn expand_macros_to_string(&mut self, expr: ast::Expr) -> Option<(ast::String, bool)> {
+        let m = match expr {
+            ast::Expr::MacroExpr(m) => m,
+            ast::Expr::Literal(l) => {
+                return match l.kind() {
+                    ast::LiteralKind::String(s) => Some((s, true)),
+                    _ => None,
+                }
+            }
+            _ => return None,
+        };
+        let e = m.macro_call()?;
+        let macro_ptr = AstPtr::new(&e);
+        let (exp, _) = self.collect_macro_call(e, macro_ptr, true, |this, expansion| {
+            expansion.and_then(|it| this.expand_macros_to_string(it))
+        })?;
+        Some((exp, false))
+    }
+
+    fn collect_format_args(
+        &mut self,
+        f: ast::FormatArgsExpr,
+        syntax_ptr: AstPtr<ast::Expr>,
+    ) -> ExprId {
+        let mut args = FormatArgumentsCollector::new();
+        f.args().for_each(|arg| {
+            args.add(FormatArgument {
+                kind: match arg.name() {
+                    Some(name) => FormatArgumentKind::Named(name.as_name()),
+                    None => FormatArgumentKind::Normal,
+                },
+                expr: self.collect_expr_opt(arg.expr()),
+            });
+        });
+        let template = f.template();
+        let fmt_snippet = template.as_ref().map(ToString::to_string);
+        let fmt = match template.and_then(|it| self.expand_macros_to_string(it)) {
+            Some((s, is_direct_literal)) => {
+                format_args::parse(&s, fmt_snippet, args, is_direct_literal, |name| {
+                    self.alloc_expr_desugared(Expr::Path(Path::from(name)))
+                })
+            }
+            None => FormatArgs { template: Default::default(), arguments: args.finish() },
+        };
+
+        // Create a list of all _unique_ (argument, format trait) combinations.
+        // E.g. "{0} {0:x} {0} {1}" -> [(0, Display), (0, LowerHex), (1, Display)]
+        let mut argmap = FxIndexSet::default();
+        for piece in fmt.template.iter() {
+            let FormatArgsPiece::Placeholder(placeholder) = piece else { continue };
+            if let Ok(index) = placeholder.argument.index {
+                argmap.insert((index, ArgumentType::Format(placeholder.format_trait)));
+            }
+        }
+
+        let lit_pieces =
+            fmt.template
+                .iter()
+                .enumerate()
+                .filter_map(|(i, piece)| {
+                    match piece {
+                        FormatArgsPiece::Literal(s) => Some(
+                            self.alloc_expr_desugared(Expr::Literal(Literal::String(s.clone()))),
+                        ),
+                        &FormatArgsPiece::Placeholder(_) => {
+                            // Inject empty string before placeholders when not already preceded by a literal piece.
+                            if i == 0
+                                || matches!(fmt.template[i - 1], FormatArgsPiece::Placeholder(_))
+                            {
+                                Some(self.alloc_expr_desugared(Expr::Literal(Literal::String(
+                                    "".into(),
+                                ))))
+                            } else {
+                                None
+                            }
+                        }
+                    }
+                })
+                .collect();
+        let lit_pieces = self.alloc_expr_desugared(Expr::Array(Array::ElementList {
+            elements: lit_pieces,
+            is_assignee_expr: false,
+        }));
+        let lit_pieces = self.alloc_expr_desugared(Expr::Ref {
+            expr: lit_pieces,
+            rawness: Rawness::Ref,
+            mutability: Mutability::Shared,
+        });
+        let format_options = {
+            // Generate:
+            //     &[format_spec_0, format_spec_1, format_spec_2]
+            let elements = fmt
+                .template
+                .iter()
+                .filter_map(|piece| {
+                    let FormatArgsPiece::Placeholder(placeholder) = piece else { return None };
+                    Some(self.make_format_spec(placeholder, &mut argmap))
+                })
+                .collect();
+            let array = self.alloc_expr_desugared(Expr::Array(Array::ElementList {
+                elements,
+                is_assignee_expr: false,
+            }));
+            self.alloc_expr_desugared(Expr::Ref {
+                expr: array,
+                rawness: Rawness::Ref,
+                mutability: Mutability::Shared,
+            })
+        };
+        let arguments = &*fmt.arguments.arguments;
+
+        let args = if arguments.is_empty() {
+            let expr = self.alloc_expr_desugared(Expr::Array(Array::ElementList {
+                elements: Box::default(),
+                is_assignee_expr: false,
+            }));
+            self.alloc_expr_desugared(Expr::Ref {
+                expr,
+                rawness: Rawness::Ref,
+                mutability: Mutability::Shared,
+            })
+        } else {
+            // Generate:
+            //     &match (&arg0, &arg1, &…) {
+            //         args => [
+            //             <core::fmt::Argument>::new_display(args.0),
+            //             <core::fmt::Argument>::new_lower_hex(args.1),
+            //             <core::fmt::Argument>::new_debug(args.0),
+            //             …
+            //         ]
+            //     }
+            let args = argmap
+                .iter()
+                .map(|&(arg_index, ty)| {
+                    let arg = self.alloc_expr_desugared(Expr::Ref {
+                        expr: arguments[arg_index].expr,
+                        rawness: Rawness::Ref,
+                        mutability: Mutability::Shared,
+                    });
+                    self.make_argument(arg, ty)
+                })
+                .collect();
+            let array = self.alloc_expr_desugared(Expr::Array(Array::ElementList {
+                elements: args,
+                is_assignee_expr: false,
+            }));
+            self.alloc_expr_desugared(Expr::Ref {
+                expr: array,
+                rawness: Rawness::Ref,
+                mutability: Mutability::Shared,
+            })
+        };
+
+        // Generate:
+        //     <core::fmt::Arguments>::new_v1_formatted(
+        //         lit_pieces,
+        //         args,
+        //         format_options,
+        //         unsafe { ::core::fmt::UnsafeArg::new() }
+        //     )
+
+        let Some(new_v1_formatted) =
+            LangItem::FormatArguments.ty_rel_path(self.db, self.krate, name![new_v1_formatted])
+        else {
+            return self.missing_expr();
+        };
+        let Some(unsafe_arg_new) =
+            LangItem::FormatUnsafeArg.ty_rel_path(self.db, self.krate, name![new])
+        else {
+            return self.missing_expr();
+        };
+        let new_v1_formatted = self.alloc_expr_desugared(Expr::Path(new_v1_formatted));
+
+        let unsafe_arg_new = self.alloc_expr_desugared(Expr::Path(unsafe_arg_new));
+        let unsafe_arg_new = self.alloc_expr_desugared(Expr::Call {
+            callee: unsafe_arg_new,
+            args: Box::default(),
+            is_assignee_expr: false,
+        });
+        let unsafe_arg_new = self.alloc_expr_desugared(Expr::Unsafe {
+            id: None,
+            statements: Box::default(),
+            tail: Some(unsafe_arg_new),
+        });
+
+        self.alloc_expr(
+            Expr::Call {
+                callee: new_v1_formatted,
+                args: Box::new([lit_pieces, args, format_options, unsafe_arg_new]),
+                is_assignee_expr: false,
+            },
+            syntax_ptr,
+        )
+    }
+
+    /// Generate a hir expression for a format_args placeholder specification.
+    ///
+    /// Generates
+    ///
+    /// ```text
+    ///     <core::fmt::rt::Placeholder::new(
+    ///         …usize, // position
+    ///         '…', // fill
+    ///         <core::fmt::rt::Alignment>::…, // alignment
+    ///         …u32, // flags
+    ///         <core::fmt::rt::Count::…>, // width
+    ///         <core::fmt::rt::Count::…>, // precision
+    ///     )
+    /// ```
+    fn make_format_spec(
+        &mut self,
+        placeholder: &FormatPlaceholder,
+        argmap: &mut FxIndexSet<(usize, ArgumentType)>,
+    ) -> ExprId {
+        let position = match placeholder.argument.index {
+            Ok(arg_index) => {
+                let (i, _) =
+                    argmap.insert_full((arg_index, ArgumentType::Format(placeholder.format_trait)));
+                self.alloc_expr_desugared(Expr::Literal(Literal::Uint(
+                    i as u128,
+                    Some(BuiltinUint::Usize),
+                )))
+            }
+            Err(_) => self.missing_expr(),
+        };
+        let &FormatOptions {
+            ref width,
+            ref precision,
+            alignment,
+            fill,
+            sign,
+            alternate,
+            zero_pad,
+            debug_hex,
+        } = &placeholder.format_options;
+        let fill = self.alloc_expr_desugared(Expr::Literal(Literal::Char(fill.unwrap_or(' '))));
+
+        let align = {
+            let align = LangItem::FormatAlignment.ty_rel_path(
+                self.db,
+                self.krate,
+                match alignment {
+                    Some(FormatAlignment::Left) => name![Left],
+                    Some(FormatAlignment::Right) => name![Right],
+                    Some(FormatAlignment::Center) => name![Center],
+                    None => name![Unknown],
+                },
+            );
+            match align {
+                Some(path) => self.alloc_expr_desugared(Expr::Path(path)),
+                None => self.missing_expr(),
+            }
+        };
+        // This needs to match `Flag` in library/core/src/fmt/rt.rs.
+        let flags: u32 = ((sign == Some(FormatSign::Plus)) as u32)
+            | ((sign == Some(FormatSign::Minus)) as u32) << 1
+            | (alternate as u32) << 2
+            | (zero_pad as u32) << 3
+            | ((debug_hex == Some(FormatDebugHex::Lower)) as u32) << 4
+            | ((debug_hex == Some(FormatDebugHex::Upper)) as u32) << 5;
+        let flags = self.alloc_expr_desugared(Expr::Literal(Literal::Uint(
+            flags as u128,
+            Some(BuiltinUint::U32),
+        )));
+        let precision = self.make_count(&precision, argmap);
+        let width = self.make_count(&width, argmap);
+
+        let format_placeholder_new = {
+            let format_placeholder_new =
+                LangItem::FormatPlaceholder.ty_rel_path(self.db, self.krate, name![new]);
+            match format_placeholder_new {
+                Some(path) => self.alloc_expr_desugared(Expr::Path(path)),
+                None => self.missing_expr(),
+            }
+        };
+
+        self.alloc_expr_desugared(Expr::Call {
+            callee: format_placeholder_new,
+            args: Box::new([position, fill, align, flags, precision, width]),
+            is_assignee_expr: false,
+        })
+    }
+
+    /// Generate a hir expression for a format_args Count.
+    ///
+    /// Generates:
+    ///
+    /// ```text
+    ///     <core::fmt::rt::Count>::Is(…)
+    /// ```
+    ///
+    /// or
+    ///
+    /// ```text
+    ///     <core::fmt::rt::Count>::Param(…)
+    /// ```
+    ///
+    /// or
+    ///
+    /// ```text
+    ///     <core::fmt::rt::Count>::Implied
+    /// ```
+    fn make_count(
+        &mut self,
+        count: &Option<FormatCount>,
+        argmap: &mut FxIndexSet<(usize, ArgumentType)>,
+    ) -> ExprId {
+        match count {
+            Some(FormatCount::Literal(n)) => {
+                match LangItem::FormatCount.ty_rel_path(self.db, self.krate, name![Is]) {
+                    Some(count_is) => {
+                        let count_is = self.alloc_expr_desugared(Expr::Path(count_is));
+                        let args = self.alloc_expr_desugared(Expr::Literal(Literal::Uint(
+                            *n as u128,
+                            Some(BuiltinUint::Usize),
+                        )));
+                        self.alloc_expr_desugared(Expr::Call {
+                            callee: count_is,
+                            args: Box::new([args]),
+                            is_assignee_expr: false,
+                        })
+                    }
+                    None => self.missing_expr(),
+                }
+            }
+            Some(FormatCount::Argument(arg)) => {
+                if let Ok(arg_index) = arg.index {
+                    let (i, _) = argmap.insert_full((arg_index, ArgumentType::Usize));
+
+                    match LangItem::FormatCount.ty_rel_path(self.db, self.krate, name![Param]) {
+                        Some(count_param) => {
+                            let count_param = self.alloc_expr_desugared(Expr::Path(count_param));
+                            let args = self.alloc_expr_desugared(Expr::Literal(Literal::Uint(
+                                i as u128,
+                                Some(BuiltinUint::Usize),
+                            )));
+                            self.alloc_expr_desugared(Expr::Call {
+                                callee: count_param,
+                                args: Box::new([args]),
+                                is_assignee_expr: false,
+                            })
+                        }
+                        None => self.missing_expr(),
+                    }
+                } else {
+                    self.missing_expr()
+                }
+            }
+            None => match LangItem::FormatCount.ty_rel_path(self.db, self.krate, name![Implied]) {
+                Some(count_param) => self.alloc_expr_desugared(Expr::Path(count_param)),
+                None => self.missing_expr(),
+            },
+        }
+    }
+
+    /// Generate a hir expression representing an argument to a format_args invocation.
+    ///
+    /// Generates:
+    ///
+    /// ```text
+    ///     <core::fmt::Argument>::new_…(arg)
+    /// ```
+    fn make_argument(&mut self, arg: ExprId, ty: ArgumentType) -> ExprId {
+        use ArgumentType::*;
+        use FormatTrait::*;
+        match LangItem::FormatArgument.ty_rel_path(
+            self.db,
+            self.krate,
+            match ty {
+                Format(Display) => name![new_display],
+                Format(Debug) => name![new_debug],
+                Format(LowerExp) => name![new_lower_exp],
+                Format(UpperExp) => name![new_upper_exp],
+                Format(Octal) => name![new_octal],
+                Format(Pointer) => name![new_pointer],
+                Format(Binary) => name![new_binary],
+                Format(LowerHex) => name![new_lower_hex],
+                Format(UpperHex) => name![new_upper_hex],
+                Usize => name![from_usize],
+            },
+        ) {
+            Some(new_fn) => {
+                let new_fn = self.alloc_expr_desugared(Expr::Path(new_fn));
+                self.alloc_expr_desugared(Expr::Call {
+                    callee: new_fn,
+                    args: Box::new([arg]),
+                    is_assignee_expr: false,
+                })
+            }
+            None => self.missing_expr(),
+        }
+    }
+    // endregion: format
 }
 
 fn pat_literal_to_hir(lit: &ast::LiteralPat) -> Option<(Literal, ast::Literal)> {
@@ -1606,3 +2033,9 @@ fn comma_follows_token(t: Option<syntax::SyntaxToken>) -> bool {
     (|| syntax::algo::skip_trivia_token(t?.next_token()?, syntax::Direction::Next))()
         .map_or(false, |it| it.kind() == syntax::T![,])
 }
+
+#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
+enum ArgumentType {
+    Format(FormatTrait),
+    Usize,
+}

crates/hir-def/src/body/pretty.rs

@@ -2,7 +2,7 @@
 
 use std::fmt::{self, Write};
 
-use hir_expand::db::ExpandDatabase;
+use itertools::Itertools;
 use syntax::ast::HasName;
 
 use crate::{
@@ -51,8 +51,7 @@ pub(super) fn print_body_hir(db: &dyn DefDatabase, body: &Body, owner: DefWithBo
         }
     };
 
-    let mut p =
+    let mut p = Printer { db, body, buf: header, indent_level: 0, needs_indent: false };
-        Printer { db: db.upcast(), body, buf: header, indent_level: 0, needs_indent: false };
     if let DefWithBodyId::FunctionId(it) = owner {
         p.buf.push('(');
         body.params.iter().zip(&db.function_data(it).params).for_each(|(&param, ty)| {
@@ -76,8 +75,7 @@ pub(super) fn print_expr_hir(
     _owner: DefWithBodyId,
     expr: ExprId,
 ) -> String {
-    let mut p =
+    let mut p = Printer { db, body, buf: String::new(), indent_level: 0, needs_indent: false };
-        Printer { db: db.upcast(), body, buf: String::new(), indent_level: 0, needs_indent: false };
     p.print_expr(expr);
     p.buf
 }
@@ -98,7 +96,7 @@ macro_rules! wln {
 }
 
 struct Printer<'a> {
-    db: &'a dyn ExpandDatabase,
+    db: &'a dyn DefDatabase,
     body: &'a Body,
     buf: String,
     indent_level: usize,
@@ -142,9 +140,14 @@ impl Printer<'_> {
     }
 
     fn newline(&mut self) {
-        match self.buf.chars().rev().find(|ch| *ch != ' ') {
+        match self.buf.chars().rev().find_position(|ch| *ch != ' ') {
-            Some('\n') | None => {}
+            Some((_, '\n')) | None => {}
-            _ => writeln!(self).unwrap(),
+            Some((idx, _)) => {
+                if idx != 0 {
+                    self.buf.drain(self.buf.len() - idx..);
+                }
+                writeln!(self).unwrap()
+            }
         }
     }
 
@@ -154,6 +157,19 @@ impl Printer<'_> {
         match expr {
             Expr::Missing => w!(self, "<EFBFBD>"),
             Expr::Underscore => w!(self, "_"),
+            Expr::InlineAsm(_) => w!(self, "builtin#asm(_)"),
+            Expr::OffsetOf(offset_of) => {
+                w!(self, "builtin#offset_of(");
+                self.print_type_ref(&offset_of.container);
+                w!(
+                    self,
+                    ", {})",
+                    offset_of
+                        .fields
+                        .iter()
+                        .format_with(".", |field, f| f(&field.display(self.db.upcast())))
+                );
+            }
             Expr::Path(path) => self.print_path(path),
             Expr::If { condition, then_branch, else_branch } => {
                 w!(self, "if ");
@@ -173,7 +189,7 @@ impl Printer<'_> {
             }
             Expr::Loop { body, label } => {
                 if let Some(lbl) = label {
-                    w!(self, "{}: ", self.body[*lbl].name.display(self.db));
+                    w!(self, "{}: ", self.body[*lbl].name.display(self.db.upcast()));
                 }
                 w!(self, "loop ");
                 self.print_expr(*body);
@@ -193,7 +209,7 @@ impl Printer<'_> {
             }
             Expr::MethodCall { receiver, method_name, args, generic_args } => {
                 self.print_expr(*receiver);
-                w!(self, ".{}", method_name.display(self.db));
+                w!(self, ".{}", method_name.display(self.db.upcast()));
                 if let Some(args) = generic_args {
                     w!(self, "::<");
                     print_generic_args(self.db, args, self).unwrap();
@@ -231,13 +247,13 @@ impl Printer<'_> {
             Expr::Continue { label } => {
                 w!(self, "continue");
                 if let Some(lbl) = label {
-                    w!(self, " {}", self.body[*lbl].name.display(self.db));
+                    w!(self, " {}", self.body[*lbl].name.display(self.db.upcast()));
                 }
             }
             Expr::Break { expr, label } => {
                 w!(self, "break");
                 if let Some(lbl) = label {
-                    w!(self, " {}", self.body[*lbl].name.display(self.db));
+                    w!(self, " {}", self.body[*lbl].name.display(self.db.upcast()));
                 }
                 if let Some(expr) = expr {
                     self.whitespace();
@@ -276,7 +292,7 @@ impl Printer<'_> {
                 w!(self, "{{");
                 self.indented(|p| {
                     for field in &**fields {
-                        w!(p, "{}: ", field.name.display(self.db));
+                        w!(p, "{}: ", field.name.display(self.db.upcast()));
                         p.print_expr(field.expr);
                         wln!(p, ",");
                     }
@@ -293,7 +309,7 @@ impl Printer<'_> {
             }
             Expr::Field { expr, name } => {
                 self.print_expr(*expr);
-                w!(self, ".{}", name.display(self.db));
+                w!(self, ".{}", name.display(self.db.upcast()));
             }
             Expr::Await { expr } => {
                 self.print_expr(*expr);
@@ -431,7 +447,8 @@ impl Printer<'_> {
             }
             Expr::Literal(lit) => self.print_literal(lit),
             Expr::Block { id: _, statements, tail, label } => {
-                let label = label.map(|lbl| format!("{}: ", self.body[lbl].name.display(self.db)));
+                let label =
+                    label.map(|lbl| format!("{}: ", self.body[lbl].name.display(self.db.upcast())));
                 self.print_block(label.as_deref(), statements, tail);
             }
             Expr::Unsafe { id: _, statements, tail } => {
@@ -507,7 +524,7 @@ impl Printer<'_> {
                 w!(self, " {{");
                 self.indented(|p| {
                     for arg in args.iter() {
-                        w!(p, "{}: ", arg.name.display(self.db));
+                        w!(p, "{}: ", arg.name.display(self.db.upcast()));
                         p.print_pat(arg.pat);
                         wln!(p, ",");
                     }
@@ -666,6 +683,6 @@ impl Printer<'_> {
             BindingAnnotation::Ref => "ref ",
             BindingAnnotation::RefMut => "ref mut ",
         };
-        w!(self, "{}{}", mode, name.display(self.db));
+        w!(self, "{}{}", mode, name.display(self.db.upcast()));
     }
 }

crates/hir-def/src/body/tests.rs

@@ -1,13 +1,13 @@
 mod block;
 
 use base_db::{fixture::WithFixture, SourceDatabase};
-use expect_test::Expect;
+use expect_test::{expect, Expect};
 
 use crate::{test_db::TestDB, ModuleDefId};
 
 use super::*;
 
-fn lower(ra_fixture: &str) -> Arc<Body> {
+fn lower(ra_fixture: &str) -> (TestDB, Arc<Body>, DefWithBodyId) {
     let db = TestDB::with_files(ra_fixture);
 
     let krate = db.crate_graph().iter().next().unwrap();
@@ -21,8 +21,10 @@ fn lower(ra_fixture: &str) -> Arc<Body> {
             }
         }
     }
+    let fn_def = fn_def.unwrap().into();
 
-    db.body(fn_def.unwrap().into())
+    let body = db.body(fn_def);
+    (db, body, fn_def)
 }
 
 fn def_map_at(ra_fixture: &str) -> String {
@@ -138,3 +140,84 @@ mod m {
 "#,
     );
 }
+
+#[test]
+fn desugar_builtin_format_args() {
+    // Regression test for a path resolution bug introduced with inner item handling.
+    let (db, body, def) = lower(
+        r#"
+//- minicore: fmt
+fn main() {
+    let are = "are";
+    let count = 10;
+    builtin#format_args("hello {count:02} {} friends, we {are:?} {0}{last}", "fancy", last = "!");
+}
+"#,
+    );
+
+    expect![[r#"
+        fn main() {
+            let are = "are";
+            let count = 10;
+            builtin#lang(Arguments::new_v1_formatted)(
+                &[
+                    "\"hello ", " ", " friends, we ", " ", "", "\"",
+                ],
+                &[
+                    builtin#lang(Argument::new_display)(
+                        &count,
+                    ), builtin#lang(Argument::new_display)(
+                        &"fancy",
+                    ), builtin#lang(Argument::new_debug)(
+                        &are,
+                    ), builtin#lang(Argument::new_display)(
+                        &"!",
+                    ),
+                ],
+                &[
+                    builtin#lang(Placeholder::new)(
+                        0usize,
+                        ' ',
+                        builtin#lang(Alignment::Unknown),
+                        8u32,
+                        builtin#lang(Count::Implied),
+                        builtin#lang(Count::Is)(
+                            2usize,
+                        ),
+                    ), builtin#lang(Placeholder::new)(
+                        1usize,
+                        ' ',
+                        builtin#lang(Alignment::Unknown),
+                        0u32,
+                        builtin#lang(Count::Implied),
+                        builtin#lang(Count::Implied),
+                    ), builtin#lang(Placeholder::new)(
+                        2usize,
+                        ' ',
+                        builtin#lang(Alignment::Unknown),
+                        0u32,
+                        builtin#lang(Count::Implied),
+                        builtin#lang(Count::Implied),
+                    ), builtin#lang(Placeholder::new)(
+                        1usize,
+                        ' ',
+                        builtin#lang(Alignment::Unknown),
+                        0u32,
+                        builtin#lang(Count::Implied),
+                        builtin#lang(Count::Implied),
+                    ), builtin#lang(Placeholder::new)(
+                        3usize,
+                        ' ',
+                        builtin#lang(Alignment::Unknown),
+                        0u32,
+                        builtin#lang(Count::Implied),
+                        builtin#lang(Count::Implied),
+                    ),
+                ],
+                unsafe {
+                    builtin#lang(UnsafeArg::new)()
+                },
+            );
+        }"#]]
+    .assert_eq(&body.pretty_print(&db, def))
+}

crates/hir-def/src/data/adt.rs

@@ -447,6 +447,7 @@ impl VariantData {
         }
     }
 
+    // FIXME: Linear lookup
     pub fn field(&self, name: &Name) -> Option<LocalFieldId> {
         self.fields().iter().find_map(|(id, data)| if &data.name == name { Some(id) } else { None })
     }

crates/hir-def/src/find_path.rs

@@ -37,6 +37,20 @@ pub fn find_path_prefixed(
     find_path_inner(db, item, from, Some(prefix_kind), prefer_no_std)
 }
 
+#[derive(Copy, Clone, Debug)]
+enum Stability {
+    Unstable,
+    Stable,
+}
+use Stability::*;
+
+fn zip_stability(a: Stability, b: Stability) -> Stability {
+    match (a, b) {
+        (Stable, Stable) => Stable,
+        _ => Unstable,
+    }
+}
+
 const MAX_PATH_LEN: usize = 15;
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
@@ -95,7 +109,8 @@ fn find_path_inner(
             MAX_PATH_LEN,
             prefixed,
             prefer_no_std || db.crate_supports_no_std(crate_root.krate),
-        );
+        )
+        .map(|(item, _)| item);
     }
 
     // - if the item is already in scope, return the name under which it is
@@ -143,6 +158,7 @@ fn find_path_inner(
         prefer_no_std || db.crate_supports_no_std(crate_root.krate),
         scope_name,
     )
+    .map(|(item, _)| item)
 }
 
 fn find_path_for_module(
@@ -155,7 +171,7 @@ fn find_path_for_module(
     max_len: usize,
     prefixed: Option<PrefixKind>,
     prefer_no_std: bool,
-) -> Option<ModPath> {
+) -> Option<(ModPath, Stability)> {
     if max_len == 0 {
         return None;
     }
@@ -165,19 +181,19 @@ fn find_path_for_module(
     let scope_name = find_in_scope(db, def_map, from, ItemInNs::Types(module_id.into()));
     if prefixed.is_none() {
         if let Some(scope_name) = scope_name {
-            return Some(ModPath::from_segments(PathKind::Plain, Some(scope_name)));
+            return Some((ModPath::from_segments(PathKind::Plain, Some(scope_name)), Stable));
         }
     }
 
     // - if the item is the crate root, return `crate`
     if module_id == crate_root {
-        return Some(ModPath::from_segments(PathKind::Crate, None));
+        return Some((ModPath::from_segments(PathKind::Crate, None), Stable));
     }
 
     // - if relative paths are fine, check if we are searching for a parent
     if prefixed.filter(PrefixKind::is_absolute).is_none() {
         if let modpath @ Some(_) = find_self_super(def_map, module_id, from) {
-            return modpath;
+            return modpath.zip(Some(Stable));
         }
     }
 
@@ -201,14 +217,14 @@ fn find_path_for_module(
             } else {
                 PathKind::Plain
             };
-            return Some(ModPath::from_segments(kind, Some(name)));
+            return Some((ModPath::from_segments(kind, Some(name)), Stable));
         }
     }
 
     if let value @ Some(_) =
         find_in_prelude(db, &root_def_map, &def_map, ItemInNs::Types(module_id.into()), from)
     {
-        return value;
+        return value.zip(Some(Stable));
     }
     calculate_best_path(
         db,
@@ -301,11 +317,19 @@ fn calculate_best_path(
     mut prefixed: Option<PrefixKind>,
     prefer_no_std: bool,
     scope_name: Option<Name>,
-) -> Option<ModPath> {
+) -> Option<(ModPath, Stability)> {
     if max_len <= 1 {
         return None;
     }
     let mut best_path = None;
+    let update_best_path =
+        |best_path: &mut Option<_>, new_path: (ModPath, Stability)| match best_path {
+            Some((old_path, old_stability)) => {
+                *old_path = new_path.0;
+                *old_stability = zip_stability(*old_stability, new_path.1);
+            }
+            None => *best_path = Some(new_path),
+        };
     // Recursive case:
     // - otherwise, look for modules containing (reexporting) it and import it from one of those
     if item.krate(db) == Some(from.krate) {
@@ -328,14 +352,14 @@ fn calculate_best_path(
                 prefixed,
                 prefer_no_std,
             ) {
-                path.push_segment(name);
+                path.0.push_segment(name);
 
-                let new_path = match best_path {
+                let new_path = match best_path.take() {
                     Some(best_path) => select_best_path(best_path, path, prefer_no_std),
                     None => path,
                 };
-                best_path_len = new_path.len();
+                best_path_len = new_path.0.len();
-                best_path = Some(new_path);
+                update_best_path(&mut best_path, new_path);
             }
         }
     } else {
@@ -354,7 +378,7 @@ fn calculate_best_path(
 
                 // Determine best path for containing module and append last segment from `info`.
                 // FIXME: we should guide this to look up the path locally, or from the same crate again?
-                let mut path = find_path_for_module(
+                let (mut path, path_stability) = find_path_for_module(
                     db,
                     def_map,
                     visited_modules,
@@ -367,16 +391,19 @@ fn calculate_best_path(
                 )?;
                 cov_mark::hit!(partially_imported);
                 path.push_segment(info.name.clone());
-                Some(path)
+                Some((
+                    path,
+                    zip_stability(path_stability, if info.is_unstable { Unstable } else { Stable }),
+                ))
             })
         });
 
         for path in extern_paths {
-            let new_path = match best_path {
+            let new_path = match best_path.take() {
                 Some(best_path) => select_best_path(best_path, path, prefer_no_std),
                 None => path,
             };
-            best_path = Some(new_path);
+            update_best_path(&mut best_path, new_path);
         }
     }
     if let Some(module) = item.module(db) {
@@ -387,15 +414,24 @@ fn calculate_best_path(
     }
     match prefixed.map(PrefixKind::prefix) {
         Some(prefix) => best_path.or_else(|| {
-            scope_name.map(|scope_name| ModPath::from_segments(prefix, Some(scope_name)))
+            scope_name.map(|scope_name| (ModPath::from_segments(prefix, Some(scope_name)), Stable))
         }),
         None => best_path,
     }
 }
 
-fn select_best_path(old_path: ModPath, new_path: ModPath, prefer_no_std: bool) -> ModPath {
+fn select_best_path(
+    old_path: (ModPath, Stability),
+    new_path: (ModPath, Stability),
+    prefer_no_std: bool,
+) -> (ModPath, Stability) {
+    match (old_path.1, new_path.1) {
+        (Stable, Unstable) => return old_path,
+        (Unstable, Stable) => return new_path,
+        _ => {}
+    }
     const STD_CRATES: [Name; 3] = [known::std, known::core, known::alloc];
-    match (old_path.segments().first(), new_path.segments().first()) {
+    match (old_path.0.segments().first(), new_path.0.segments().first()) {
         (Some(old), Some(new)) if STD_CRATES.contains(old) && STD_CRATES.contains(new) => {
             let rank = match prefer_no_std {
                 false => |name: &Name| match name {
@@ -416,7 +452,7 @@ fn select_best_path(old_path: ModPath, new_path: ModPath, prefer_no_std: bool) -
             match nrank.cmp(&orank) {
                 Ordering::Less => old_path,
                 Ordering::Equal => {
-                    if new_path.len() < old_path.len() {
+                    if new_path.0.len() < old_path.0.len() {
                         new_path
                     } else {
                         old_path
@@ -426,7 +462,7 @@ fn select_best_path(old_path: ModPath, new_path: ModPath, prefer_no_std: bool) -
             }
         }
         _ => {
-            if new_path.len() < old_path.len() {
+            if new_path.0.len() < old_path.0.len() {
                 new_path
             } else {
                 old_path
@@ -1360,4 +1396,29 @@ pub mod ops {
             "std::ops::Deref",
         );
     }
+
+    #[test]
+    fn respect_unstable_modules() {
+        check_found_path(
+            r#"
+//- /main.rs crate:main deps:std,core
+#![no_std]
+extern crate std;
+$0
+//- /longer.rs crate:std deps:core
+pub mod error {
+    pub use core::error::Error;
+}
+//- /core.rs crate:core
+pub mod error {
+    #![unstable(feature = "error_in_core", issue = "103765")]
+    pub trait Error {}
+}
+"#,
+            "std::error::Error",
+            "std::error::Error",
+            "std::error::Error",
+            "std::error::Error",
+        );
+    }
 }

crates/hir-def/src/hir.rs

@@ -13,6 +13,7 @@
 //! See also a neighboring `body` module.
 
 pub mod type_ref;
+pub mod format_args;
 
 use std::fmt;
 
@@ -117,7 +118,6 @@ impl From<ast::LiteralKind> for Literal {
     fn from(ast_lit_kind: ast::LiteralKind) -> Self {
         use ast::LiteralKind;
         match ast_lit_kind {
-            // FIXME: these should have actual values filled in, but unsure on perf impact
             LiteralKind::IntNumber(lit) => {
                 if let builtin @ Some(_) = lit.suffix().and_then(BuiltinFloat::from_suffix) {
                     Literal::Float(
@@ -281,6 +281,19 @@ pub enum Expr {
     Array(Array),
     Literal(Literal),
     Underscore,
+    OffsetOf(OffsetOf),
+    InlineAsm(InlineAsm),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct OffsetOf {
+    pub container: Interned<TypeRef>,
+    pub fields: Box<[Name]>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct InlineAsm {
+    pub e: ExprId,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -341,7 +354,8 @@ impl Expr {
     pub fn walk_child_exprs(&self, mut f: impl FnMut(ExprId)) {
         match self {
             Expr::Missing => {}
-            Expr::Path(_) => {}
+            Expr::Path(_) | Expr::OffsetOf(_) => {}
+            Expr::InlineAsm(it) => f(it.e),
             Expr::If { condition, then_branch, else_branch } => {
                 f(*condition);
                 f(*then_branch);

crates/hir-def/src/hir/format_args.rs

@@ -0,0 +1,502 @@
+//! Parses `format_args` input.
+use std::mem;
+
+use hir_expand::name::Name;
+use rustc_parse_format as parse;
+use syntax::{
+    ast::{self, IsString},
+    AstToken, SmolStr, TextRange,
+};
+
+use crate::hir::ExprId;
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FormatArgs {
+    pub template: Box<[FormatArgsPiece]>,
+    pub arguments: FormatArguments,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FormatArguments {
+    pub arguments: Box<[FormatArgument]>,
+    pub num_unnamed_args: usize,
+    pub num_explicit_args: usize,
+    pub names: Box<[(Name, usize)]>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum FormatArgsPiece {
+    Literal(Box<str>),
+    Placeholder(FormatPlaceholder),
+}
+
+#[derive(Copy, Debug, Clone, PartialEq, Eq)]
+pub struct FormatPlaceholder {
+    /// Index into [`FormatArgs::arguments`].
+    pub argument: FormatArgPosition,
+    /// The span inside the format string for the full `{…}` placeholder.
+    pub span: Option<TextRange>,
+    /// `{}`, `{:?}`, or `{:x}`, etc.
+    pub format_trait: FormatTrait,
+    /// `{}` or `{:.5}` or `{:-^20}`, etc.
+    pub format_options: FormatOptions,
+}
+
+#[derive(Copy, Debug, Clone, PartialEq, Eq)]
+pub struct FormatArgPosition {
+    /// Which argument this position refers to (Ok),
+    /// or would've referred to if it existed (Err).
+    pub index: Result<usize, usize>,
+    /// What kind of position this is. See [`FormatArgPositionKind`].
+    pub kind: FormatArgPositionKind,
+    /// The span of the name or number.
+    pub span: Option<TextRange>,
+}
+
+#[derive(Copy, Debug, Clone, PartialEq, Eq)]
+pub enum FormatArgPositionKind {
+    /// `{}` or `{:.*}`
+    Implicit,
+    /// `{1}` or `{:1$}` or `{:.1$}`
+    Number,
+    /// `{a}` or `{:a$}` or `{:.a$}`
+    Named,
+}
+
+#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
+pub enum FormatTrait {
+    /// `{}`
+    Display,
+    /// `{:?}`
+    Debug,
+    /// `{:e}`
+    LowerExp,
+    /// `{:E}`
+    UpperExp,
+    /// `{:o}`
+    Octal,
+    /// `{:p}`
+    Pointer,
+    /// `{:b}`
+    Binary,
+    /// `{:x}`
+    LowerHex,
+    /// `{:X}`
+    UpperHex,
+}
+
+#[derive(Copy, Clone, Default, Debug, PartialEq, Eq)]
+pub struct FormatOptions {
+    /// The width. E.g. `{:5}` or `{:width$}`.
+    pub width: Option<FormatCount>,
+    /// The precision. E.g. `{:.5}` or `{:.precision$}`.
+    pub precision: Option<FormatCount>,
+    /// The alignment. E.g. `{:>}` or `{:<}` or `{:^}`.
+    pub alignment: Option<FormatAlignment>,
+    /// The fill character. E.g. the `.` in `{:.>10}`.
+    pub fill: Option<char>,
+    /// The `+` or `-` flag.
+    pub sign: Option<FormatSign>,
+    /// The `#` flag.
+    pub alternate: bool,
+    /// The `0` flag. E.g. the `0` in `{:02x}`.
+    pub zero_pad: bool,
+    /// The `x` or `X` flag (for `Debug` only). E.g. the `x` in `{:x?}`.
+    pub debug_hex: Option<FormatDebugHex>,
+}
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum FormatSign {
+    /// The `+` flag.
+    Plus,
+    /// The `-` flag.
+    Minus,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum FormatDebugHex {
+    /// The `x` flag in `{:x?}`.
+    Lower,
+    /// The `X` flag in `{:X?}`.
+    Upper,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum FormatAlignment {
+    /// `{:<}`
+    Left,
+    /// `{:>}`
+    Right,
+    /// `{:^}`
+    Center,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum FormatCount {
+    /// `{:5}` or `{:.5}`
+    Literal(usize),
+    /// `{:.*}`, `{:.5$}`, or `{:a$}`, etc.
+    Argument(FormatArgPosition),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FormatArgument {
+    pub kind: FormatArgumentKind,
+    pub expr: ExprId,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum FormatArgumentKind {
+    /// `format_args(…, arg)`
+    Normal,
+    /// `format_args(…, arg = 1)`
+    Named(Name),
+    /// `format_args("… {arg} …")`
+    Captured(Name),
+}
+
+// Only used in parse_args and report_invalid_references,
+// to indicate how a referred argument was used.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum PositionUsedAs {
+    Placeholder(Option<TextRange>),
+    Precision,
+    Width,
+}
+use PositionUsedAs::*;
+
+pub(crate) fn parse(
+    s: &ast::String,
+    fmt_snippet: Option<String>,
+    mut args: FormatArgumentsCollector,
+    is_direct_literal: bool,
+    mut synth: impl FnMut(Name) -> ExprId,
+) -> FormatArgs {
+    let text = s.text();
+    let str_style = match s.quote_offsets() {
+        Some(offsets) => {
+            let raw = u32::from(offsets.quotes.0.len()) - 1;
+            (raw != 0).then_some(raw as usize)
+        }
+        None => None,
+    };
+    let mut parser =
+        parse::Parser::new(text, str_style, fmt_snippet, false, parse::ParseMode::Format);
+
+    let mut pieces = Vec::new();
+    while let Some(piece) = parser.next() {
+        if !parser.errors.is_empty() {
+            break;
+        } else {
+            pieces.push(piece);
+        }
+    }
+    let is_source_literal = parser.is_source_literal;
+    if !parser.errors.is_empty() {
+        // FIXME: Diagnose
+        return FormatArgs { template: Default::default(), arguments: args.finish() };
+    }
+
+    let to_span = |inner_span: parse::InnerSpan| {
+        is_source_literal.then(|| {
+            TextRange::new(inner_span.start.try_into().unwrap(), inner_span.end.try_into().unwrap())
+        })
+    };
+
+    let mut used = vec![false; args.explicit_args().len()];
+    let mut invalid_refs = Vec::new();
+    let mut numeric_refences_to_named_arg = Vec::new();
+
+    enum ArgRef<'a> {
+        Index(usize),
+        Name(&'a str, Option<TextRange>),
+    }
+    let mut lookup_arg = |arg: ArgRef<'_>,
+                          span: Option<TextRange>,
+                          used_as: PositionUsedAs,
+                          kind: FormatArgPositionKind|
+     -> FormatArgPosition {
+        let index = match arg {
+            ArgRef::Index(index) => {
+                if let Some(arg) = args.by_index(index) {
+                    used[index] = true;
+                    if arg.kind.ident().is_some() {
+                        // This was a named argument, but it was used as a positional argument.
+                        numeric_refences_to_named_arg.push((index, span, used_as));
+                    }
+                    Ok(index)
+                } else {
+                    // Doesn't exist as an explicit argument.
+                    invalid_refs.push((index, span, used_as, kind));
+                    Err(index)
+                }
+            }
+            ArgRef::Name(name, _span) => {
+                let name = Name::new_text_dont_use(SmolStr::new(name));
+                if let Some((index, _)) = args.by_name(&name) {
+                    // Name found in `args`, so we resolve it to its index.
+                    if index < args.explicit_args().len() {
+                        // Mark it as used, if it was an explicit argument.
+                        used[index] = true;
+                    }
+                    Ok(index)
+                } else {
+                    // Name not found in `args`, so we add it as an implicitly captured argument.
+                    if !is_direct_literal {
+                        // For the moment capturing variables from format strings expanded from macros is
+                        // disabled (see RFC #2795)
+                        // FIXME: Diagnose
+                    }
+                    Ok(args.add(FormatArgument {
+                        kind: FormatArgumentKind::Captured(name.clone()),
+                        // FIXME: This is problematic, we might want to synthesize a dummy
+                        // expression proper and/or desugar these.
+                        expr: synth(name),
+                    }))
+                }
+            }
+        };
+        FormatArgPosition { index, kind, span }
+    };
+
+    let mut template = Vec::new();
+    let mut unfinished_literal = String::new();
+    let mut placeholder_index = 0;
+
+    for piece in pieces {
+        match piece {
+            parse::Piece::String(s) => {
+                unfinished_literal.push_str(s);
+            }
+            parse::Piece::NextArgument(arg) => {
+                let parse::Argument { position, position_span, format } = *arg;
+                if !unfinished_literal.is_empty() {
+                    template.push(FormatArgsPiece::Literal(
+                        mem::take(&mut unfinished_literal).into_boxed_str(),
+                    ));
+                }
+
+                let span = parser.arg_places.get(placeholder_index).and_then(|&s| to_span(s));
+                placeholder_index += 1;
+
+                let position_span = to_span(position_span);
+                let argument = match position {
+                    parse::ArgumentImplicitlyIs(i) => lookup_arg(
+                        ArgRef::Index(i),
+                        position_span,
+                        Placeholder(span),
+                        FormatArgPositionKind::Implicit,
+                    ),
+                    parse::ArgumentIs(i) => lookup_arg(
+                        ArgRef::Index(i),
+                        position_span,
+                        Placeholder(span),
+                        FormatArgPositionKind::Number,
+                    ),
+                    parse::ArgumentNamed(name) => lookup_arg(
+                        ArgRef::Name(name, position_span),
+                        position_span,
+                        Placeholder(span),
+                        FormatArgPositionKind::Named,
+                    ),
+                };
+
+                let alignment = match format.align {
+                    parse::AlignUnknown => None,
+                    parse::AlignLeft => Some(FormatAlignment::Left),
+                    parse::AlignRight => Some(FormatAlignment::Right),
+                    parse::AlignCenter => Some(FormatAlignment::Center),
+                };
+
+                let format_trait = match format.ty {
+                    "" => FormatTrait::Display,
+                    "?" => FormatTrait::Debug,
+                    "e" => FormatTrait::LowerExp,
+                    "E" => FormatTrait::UpperExp,
+                    "o" => FormatTrait::Octal,
+                    "p" => FormatTrait::Pointer,
+                    "b" => FormatTrait::Binary,
+                    "x" => FormatTrait::LowerHex,
+                    "X" => FormatTrait::UpperHex,
+                    _ => {
+                        // FIXME: Diagnose
+                        FormatTrait::Display
+                    }
+                };
+
+                let precision_span = format.precision_span.and_then(to_span);
+                let precision = match format.precision {
+                    parse::CountIs(n) => Some(FormatCount::Literal(n)),
+                    parse::CountIsName(name, name_span) => Some(FormatCount::Argument(lookup_arg(
+                        ArgRef::Name(name, to_span(name_span)),
+                        precision_span,
+                        Precision,
+                        FormatArgPositionKind::Named,
+                    ))),
+                    parse::CountIsParam(i) => Some(FormatCount::Argument(lookup_arg(
+                        ArgRef::Index(i),
+                        precision_span,
+                        Precision,
+                        FormatArgPositionKind::Number,
+                    ))),
+                    parse::CountIsStar(i) => Some(FormatCount::Argument(lookup_arg(
+                        ArgRef::Index(i),
+                        precision_span,
+                        Precision,
+                        FormatArgPositionKind::Implicit,
+                    ))),
+                    parse::CountImplied => None,
+                };
+
+                let width_span = format.width_span.and_then(to_span);
+                let width = match format.width {
+                    parse::CountIs(n) => Some(FormatCount::Literal(n)),
+                    parse::CountIsName(name, name_span) => Some(FormatCount::Argument(lookup_arg(
+                        ArgRef::Name(name, to_span(name_span)),
+                        width_span,
+                        Width,
+                        FormatArgPositionKind::Named,
+                    ))),
+                    parse::CountIsParam(i) => Some(FormatCount::Argument(lookup_arg(
+                        ArgRef::Index(i),
+                        width_span,
+                        Width,
+                        FormatArgPositionKind::Number,
+                    ))),
+                    parse::CountIsStar(_) => unreachable!(),
+                    parse::CountImplied => None,
+                };
+
+                template.push(FormatArgsPiece::Placeholder(FormatPlaceholder {
+                    argument,
+                    span,
+                    format_trait,
+                    format_options: FormatOptions {
+                        fill: format.fill,
+                        alignment,
+                        sign: format.sign.map(|s| match s {
+                            parse::Sign::Plus => FormatSign::Plus,
+                            parse::Sign::Minus => FormatSign::Minus,
+                        }),
+                        alternate: format.alternate,
+                        zero_pad: format.zero_pad,
+                        debug_hex: format.debug_hex.map(|s| match s {
+                            parse::DebugHex::Lower => FormatDebugHex::Lower,
+                            parse::DebugHex::Upper => FormatDebugHex::Upper,
+                        }),
+                        precision,
+                        width,
+                    },
+                }));
+            }
+        }
+    }
+
+    if !unfinished_literal.is_empty() {
+        template.push(FormatArgsPiece::Literal(unfinished_literal.into_boxed_str()));
+    }
+
+    if !invalid_refs.is_empty() {
+        // FIXME: Diagnose
+    }
+
+    let unused = used
+        .iter()
+        .enumerate()
+        .filter(|&(_, used)| !used)
+        .map(|(i, _)| {
+            let named = matches!(args.explicit_args()[i].kind, FormatArgumentKind::Named(_));
+            (args.explicit_args()[i].expr, named)
+        })
+        .collect::<Vec<_>>();
+
+    if !unused.is_empty() {
+        // FIXME: Diagnose
+    }
+
+    FormatArgs { template: template.into_boxed_slice(), arguments: args.finish() }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FormatArgumentsCollector {
+    arguments: Vec<FormatArgument>,
+    num_unnamed_args: usize,
+    num_explicit_args: usize,
+    names: Vec<(Name, usize)>,
+}
+
+impl FormatArgumentsCollector {
+    pub(crate) fn finish(self) -> FormatArguments {
+        FormatArguments {
+            arguments: self.arguments.into_boxed_slice(),
+            num_unnamed_args: self.num_unnamed_args,
+            num_explicit_args: self.num_explicit_args,
+            names: self.names.into_boxed_slice(),
+        }
+    }
+
+    pub fn new() -> Self {
+        Self { arguments: vec![], names: vec![], num_unnamed_args: 0, num_explicit_args: 0 }
+    }
+
+    pub fn add(&mut self, arg: FormatArgument) -> usize {
+        let index = self.arguments.len();
+        if let Some(name) = arg.kind.ident() {
+            self.names.push((name.clone(), index));
+        } else if self.names.is_empty() {
+            // Only count the unnamed args before the first named arg.
+            // (Any later ones are errors.)
+            self.num_unnamed_args += 1;
+        }
+        if !matches!(arg.kind, FormatArgumentKind::Captured(..)) {
+            // This is an explicit argument.
+            // Make sure that all arguments so far are explicit.
+            assert_eq!(
+                self.num_explicit_args,
+                self.arguments.len(),
+                "captured arguments must be added last"
+            );
+            self.num_explicit_args += 1;
+        }
+        self.arguments.push(arg);
+        index
+    }
+
+    pub fn by_name(&self, name: &Name) -> Option<(usize, &FormatArgument)> {
+        let &(_, i) = self.names.iter().find(|(n, _)| n == name)?;
+        Some((i, &self.arguments[i]))
+    }
+
+    pub fn by_index(&self, i: usize) -> Option<&FormatArgument> {
+        (i < self.num_explicit_args).then(|| &self.arguments[i])
+    }
+
+    pub fn unnamed_args(&self) -> &[FormatArgument] {
+        &self.arguments[..self.num_unnamed_args]
+    }
+
+    pub fn named_args(&self) -> &[FormatArgument] {
+        &self.arguments[self.num_unnamed_args..self.num_explicit_args]
+    }
+
+    pub fn explicit_args(&self) -> &[FormatArgument] {
+        &self.arguments[..self.num_explicit_args]
+    }
+
+    pub fn all_args(&self) -> &[FormatArgument] {
+        &self.arguments[..]
+    }
+
+    pub fn all_args_mut(&mut self) -> &mut Vec<FormatArgument> {
+        &mut self.arguments
+    }
+}
+
+impl FormatArgumentKind {
+    pub fn ident(&self) -> Option<&Name> {
+        match self {
+            Self::Normal => None,
+            Self::Named(id) => Some(id),
+            Self::Captured(id) => Some(id),
+        }
+    }
+}

crates/hir-def/src/import_map.rs

@@ -32,6 +32,8 @@ pub struct ImportInfo {
     pub is_trait_assoc_item: bool,
     /// Whether this item is annotated with `#[doc(hidden)]`.
     pub is_doc_hidden: bool,
+    /// Whether this item is annotated with `#[unstable(..)]`.
+    pub is_unstable: bool,
 }
 
 /// A map from publicly exported items to its name.
@@ -113,7 +115,6 @@ fn collect_import_map(db: &dyn DefDatabase, krate: CrateId) -> FxIndexMap<ItemIn
 
         for (name, per_ns) in visible_items {
             for (item, import) in per_ns.iter_items() {
-                // FIXME: Not yet used, but will be once we handle doc(hidden) import sources
                 let attr_id = if let Some(import) = import {
                     match import {
                         ImportOrExternCrate::ExternCrate(id) => Some(id.into()),
@@ -125,28 +126,59 @@ fn collect_import_map(db: &dyn DefDatabase, krate: CrateId) -> FxIndexMap<ItemIn
                         ItemInNs::Macros(id) => Some(id.into()),
                     }
                 };
-                let is_doc_hidden =
+                let status @ (is_doc_hidden, is_unstable) =
-                    attr_id.map_or(false, |attr_id| db.attrs(attr_id).has_doc_hidden());
+                    attr_id.map_or((false, false), |attr_id| {
+                        let attrs = db.attrs(attr_id);
+                        (attrs.has_doc_hidden(), attrs.is_unstable())
+                    });
 
                 let import_info = ImportInfo {
                     name: name.clone(),
                     container: module,
                     is_trait_assoc_item: false,
                     is_doc_hidden,
+                    is_unstable,
                 };
 
                 match depth_map.entry(item) {
-                    Entry::Vacant(entry) => _ = entry.insert((depth, is_doc_hidden)),
+                    Entry::Vacant(entry) => _ = entry.insert((depth, status)),
                     Entry::Occupied(mut entry) => {
-                        let &(occ_depth, occ_is_doc_hidden) = entry.get();
+                        let &(occ_depth, (occ_is_doc_hidden, occ_is_unstable)) = entry.get();
-                        // Prefer the one that is not doc(hidden),
+                        (depth, occ_depth);
-                        // Otherwise, if both have the same doc(hidden)-ness and the new path is shorter, prefer that one.
+                        let overwrite = match (
-                        let overwrite_entry = occ_is_doc_hidden && !is_doc_hidden
+                            is_doc_hidden,
-                            || occ_is_doc_hidden == is_doc_hidden && depth < occ_depth;
+                            occ_is_doc_hidden,
-                        if !overwrite_entry {
+                            is_unstable,
+                            occ_is_unstable,
+                        ) {
+                            // no change of hiddeness or unstableness
+                            (true, true, true, true)
+                            | (true, true, false, false)
+                            | (false, false, true, true)
+                            | (false, false, false, false) => depth < occ_depth,
+
+                            // either less hidden or less unstable, accept
+                            (true, true, false, true)
+                            | (false, true, true, true)
+                            | (false, true, false, true)
+                            | (false, true, false, false)
+                            | (false, false, false, true) => true,
+                            // more hidden or unstable, discard
+                            (true, true, true, false)
+                            | (true, false, true, true)
+                            | (true, false, true, false)
+                            | (true, false, false, false)
+                            | (false, false, true, false) => false,
+
+                            // exchanges doc(hidden) for unstable (and vice-versa),
+                            (true, false, false, true) | (false, true, true, false) => {
+                                depth < occ_depth
+                            }
+                        };
+                        if !overwrite {
                             continue;
                         }
-                        entry.insert((depth, is_doc_hidden));
+                        entry.insert((depth, status));
                     }
                 }
 
@@ -171,7 +203,7 @@ fn collect_import_map(db: &dyn DefDatabase, krate: CrateId) -> FxIndexMap<ItemIn
             }
         }
     }
-
+    map.shrink_to_fit();
     map
 }
 
@@ -200,11 +232,13 @@ fn collect_trait_assoc_items(
             ItemInNs::Values(module_def_id)
         };
 
+        let attrs = &db.attrs(item.into());
         let assoc_item_info = ImportInfo {
             container: trait_import_info.container,
             name: assoc_item_name.clone(),
             is_trait_assoc_item: true,
-            is_doc_hidden: db.attrs(item.into()).has_doc_hidden(),
+            is_doc_hidden: attrs.has_doc_hidden(),
+            is_unstable: attrs.is_unstable(),
         };
         map.insert(assoc_item, assoc_item_info);
     }

crates/hir-def/src/item_tree.rs

@@ -177,7 +177,7 @@ impl ItemTree {
     }
 
     pub fn pretty_print(&self, db: &dyn DefDatabase) -> String {
-        pretty::print_item_tree(db.upcast(), self)
+        pretty::print_item_tree(db, self)
     }
 
     fn data(&self) -> &ItemTreeData {

crates/hir-def/src/item_tree/pretty.rs

@@ -2,8 +2,6 @@
 
 use std::fmt::{self, Write};
 
-use hir_expand::db::ExpandDatabase;
-
 use crate::{
     generics::{TypeOrConstParamData, WherePredicate, WherePredicateTypeTarget},
     pretty::{print_path, print_type_bounds, print_type_ref},
@@ -12,7 +10,7 @@ use crate::{
 
 use super::*;
 
-pub(super) fn print_item_tree(db: &dyn ExpandDatabase, tree: &ItemTree) -> String {
+pub(super) fn print_item_tree(db: &dyn DefDatabase, tree: &ItemTree) -> String {
     let mut p = Printer { db, tree, buf: String::new(), indent_level: 0, needs_indent: true };
 
     if let Some(attrs) = tree.attrs.get(&AttrOwner::TopLevel) {
@@ -45,7 +43,7 @@ macro_rules! wln {
 }
 
 struct Printer<'a> {
-    db: &'a dyn ExpandDatabase,
+    db: &'a dyn DefDatabase,
     tree: &'a ItemTree,
     buf: String,
     indent_level: usize,
@@ -91,7 +89,7 @@ impl Printer<'_> {
                 self,
                 "#{}[{}{}]{}",
                 inner,
-                attr.path.display(self.db),
+                attr.path.display(self.db.upcast()),
                 attr.input.as_ref().map(|it| it.to_string()).unwrap_or_default(),
                 separated_by,
             );
@@ -106,7 +104,7 @@ impl Printer<'_> {
 
     fn print_visibility(&mut self, vis: RawVisibilityId) {
         match &self.tree[vis] {
-            RawVisibility::Module(path) => w!(self, "pub({}) ", path.display(self.db)),
+            RawVisibility::Module(path) => w!(self, "pub({}) ", path.display(self.db.upcast())),
             RawVisibility::Public => w!(self, "pub "),
         };
     }
@@ -121,7 +119,7 @@ impl Printer<'_> {
                         let Field { visibility, name, type_ref, ast_id: _ } = &this.tree[field];
                         this.print_attrs_of(field, "\n");
                         this.print_visibility(*visibility);
-                        w!(this, "{}: ", name.display(self.db));
+                        w!(this, "{}: ", name.display(self.db.upcast()));
                         this.print_type_ref(type_ref);
                         wln!(this, ",");
                     }
@@ -135,7 +133,7 @@ impl Printer<'_> {
                         let Field { visibility, name, type_ref, ast_id: _ } = &this.tree[field];
                         this.print_attrs_of(field, "\n");
                         this.print_visibility(*visibility);
-                        w!(this, "{}: ", name.display(self.db));
+                        w!(this, "{}: ", name.display(self.db.upcast()));
                         this.print_type_ref(type_ref);
                         wln!(this, ",");
                     }
@@ -168,20 +166,20 @@ impl Printer<'_> {
     fn print_use_tree(&mut self, use_tree: &UseTree) {
         match &use_tree.kind {
             UseTreeKind::Single { path, alias } => {
-                w!(self, "{}", path.display(self.db));
+                w!(self, "{}", path.display(self.db.upcast()));
                 if let Some(alias) = alias {
                     w!(self, " as {}", alias);
                 }
             }
             UseTreeKind::Glob { path } => {
                 if let Some(path) = path {
-                    w!(self, "{}::", path.display(self.db));
+                    w!(self, "{}::", path.display(self.db.upcast()));
                 }
                 w!(self, "*");
             }
             UseTreeKind::Prefixed { prefix, list } => {
                 if let Some(prefix) = prefix {
-                    w!(self, "{}::", prefix.display(self.db));
+                    w!(self, "{}::", prefix.display(self.db.upcast()));
                 }
                 w!(self, "{{");
                 for (i, tree) in list.iter().enumerate() {
@@ -209,7 +207,7 @@ impl Printer<'_> {
             ModItem::ExternCrate(it) => {
                 let ExternCrate { name, alias, visibility, ast_id: _ } = &self.tree[it];
                 self.print_visibility(*visibility);
-                w!(self, "extern crate {}", name.display(self.db));
+                w!(self, "extern crate {}", name.display(self.db.upcast()));
                 if let Some(alias) = alias {
                     w!(self, " as {}", alias);
                 }
@@ -256,7 +254,7 @@ impl Printer<'_> {
                 if let Some(abi) = abi {
                     w!(self, "extern \"{}\" ", abi);
                 }
-                w!(self, "fn {}", name.display(self.db));
+                w!(self, "fn {}", name.display(self.db.upcast()));
                 self.print_generic_params(explicit_generic_params);
                 w!(self, "(");
                 if !params.is_empty() {
@@ -290,7 +288,7 @@ impl Printer<'_> {
             ModItem::Struct(it) => {
                 let Struct { visibility, name, fields, generic_params, ast_id: _ } = &self.tree[it];
                 self.print_visibility(*visibility);
-                w!(self, "struct {}", name.display(self.db));
+                w!(self, "struct {}", name.display(self.db.upcast()));
                 self.print_generic_params(generic_params);
                 self.print_fields_and_where_clause(fields, generic_params);
                 if matches!(fields, Fields::Record(_)) {
@@ -302,7 +300,7 @@ impl Printer<'_> {
             ModItem::Union(it) => {
                 let Union { name, visibility, fields, generic_params, ast_id: _ } = &self.tree[it];
                 self.print_visibility(*visibility);
-                w!(self, "union {}", name.display(self.db));
+                w!(self, "union {}", name.display(self.db.upcast()));
                 self.print_generic_params(generic_params);
                 self.print_fields_and_where_clause(fields, generic_params);
                 if matches!(fields, Fields::Record(_)) {
@@ -314,14 +312,14 @@ impl Printer<'_> {
             ModItem::Enum(it) => {
                 let Enum { name, visibility, variants, generic_params, ast_id: _ } = &self.tree[it];
                 self.print_visibility(*visibility);
-                w!(self, "enum {}", name.display(self.db));
+                w!(self, "enum {}", name.display(self.db.upcast()));
                 self.print_generic_params(generic_params);
                 self.print_where_clause_and_opening_brace(generic_params);
                 self.indented(|this| {
                     for variant in variants.clone() {
                         let Variant { name, fields, ast_id: _ } = &this.tree[variant];
                         this.print_attrs_of(variant, "\n");
-                        w!(this, "{}", name.display(self.db));
+                        w!(this, "{}", name.display(self.db.upcast()));
                         this.print_fields(fields);
                         wln!(this, ",");
                     }
@@ -333,7 +331,7 @@ impl Printer<'_> {
                 self.print_visibility(*visibility);
                 w!(self, "const ");
                 match name {
-                    Some(name) => w!(self, "{}", name.display(self.db)),
+                    Some(name) => w!(self, "{}", name.display(self.db.upcast())),
                     None => w!(self, "_"),
                 }
                 w!(self, ": ");
@@ -347,7 +345,7 @@ impl Printer<'_> {
                 if *mutable {
                     w!(self, "mut ");
                 }
-                w!(self, "{}: ", name.display(self.db));
+                w!(self, "{}: ", name.display(self.db.upcast()));
                 self.print_type_ref(type_ref);
                 w!(self, " = _;");
                 wln!(self);
@@ -369,7 +367,7 @@ impl Printer<'_> {
                 if *is_auto {
                     w!(self, "auto ");
                 }
-                w!(self, "trait {}", name.display(self.db));
+                w!(self, "trait {}", name.display(self.db.upcast()));
                 self.print_generic_params(generic_params);
                 self.print_where_clause_and_opening_brace(generic_params);
                 self.indented(|this| {
@@ -382,7 +380,7 @@ impl Printer<'_> {
             ModItem::TraitAlias(it) => {
                 let TraitAlias { name, visibility, generic_params, ast_id: _ } = &self.tree[it];
                 self.print_visibility(*visibility);
-                w!(self, "trait {}", name.display(self.db));
+                w!(self, "trait {}", name.display(self.db.upcast()));
                 self.print_generic_params(generic_params);
                 w!(self, " = ");
                 self.print_where_clause(generic_params);
@@ -415,7 +413,7 @@ impl Printer<'_> {
                 let TypeAlias { name, visibility, bounds, type_ref, generic_params, ast_id: _ } =
                     &self.tree[it];
                 self.print_visibility(*visibility);
-                w!(self, "type {}", name.display(self.db));
+                w!(self, "type {}", name.display(self.db.upcast()));
                 self.print_generic_params(generic_params);
                 if !bounds.is_empty() {
                     w!(self, ": ");
@@ -432,7 +430,7 @@ impl Printer<'_> {
             ModItem::Mod(it) => {
                 let Mod { name, visibility, kind, ast_id: _ } = &self.tree[it];
                 self.print_visibility(*visibility);
-                w!(self, "mod {}", name.display(self.db));
+                w!(self, "mod {}", name.display(self.db.upcast()));
                 match kind {
                     ModKind::Inline { items } => {
                         w!(self, " {{");
@@ -450,16 +448,16 @@ impl Printer<'_> {
             }
             ModItem::MacroCall(it) => {
                 let MacroCall { path, ast_id: _, expand_to: _ } = &self.tree[it];
-                wln!(self, "{}!(...);", path.display(self.db));
+                wln!(self, "{}!(...);", path.display(self.db.upcast()));
             }
             ModItem::MacroRules(it) => {
                 let MacroRules { name, ast_id: _ } = &self.tree[it];
-                wln!(self, "macro_rules! {} {{ ... }}", name.display(self.db));
+                wln!(self, "macro_rules! {} {{ ... }}", name.display(self.db.upcast()));
             }
             ModItem::MacroDef(it) => {
                 let MacroDef { name, visibility, ast_id: _ } = &self.tree[it];
                 self.print_visibility(*visibility);
-                wln!(self, "macro {} {{ ... }}", name.display(self.db));
+                wln!(self, "macro {} {{ ... }}", name.display(self.db.upcast()));
             }
         }
 
@@ -491,7 +489,7 @@ impl Printer<'_> {
             }
             first = false;
             self.print_attrs_of(idx, " ");
-            w!(self, "{}", lt.name.display(self.db));
+            w!(self, "{}", lt.name.display(self.db.upcast()));
         }
         for (idx, x) in params.type_or_consts.iter() {
             if !first {
@@ -501,11 +499,11 @@ impl Printer<'_> {
             self.print_attrs_of(idx, " ");
             match x {
                 TypeOrConstParamData::TypeParamData(ty) => match &ty.name {
-                    Some(name) => w!(self, "{}", name.display(self.db)),
+                    Some(name) => w!(self, "{}", name.display(self.db.upcast())),
                     None => w!(self, "_anon_{}", idx.into_raw()),
                 },
                 TypeOrConstParamData::ConstParamData(konst) => {
-                    w!(self, "const {}: ", konst.name.display(self.db));
+                    w!(self, "const {}: ", konst.name.display(self.db.upcast()));
                     self.print_type_ref(&konst.ty);
                 }
             }
@@ -540,8 +538,8 @@ impl Printer<'_> {
                         wln!(
                             this,
                             "{}: {},",
-                            target.name.display(self.db),
+                            target.name.display(self.db.upcast()),
-                            bound.name.display(self.db)
+                            bound.name.display(self.db.upcast())
                         );
                         continue;
                     }
@@ -551,7 +549,7 @@ impl Printer<'_> {
                             if i != 0 {
                                 w!(this, ", ");
                             }
-                            w!(this, "{}", lt.display(self.db));
+                            w!(this, "{}", lt.display(self.db.upcast()));
                         }
                         w!(this, "> ");
                         (target, bound)
@@ -562,7 +560,7 @@ impl Printer<'_> {
                     WherePredicateTypeTarget::TypeRef(ty) => this.print_type_ref(ty),
                     WherePredicateTypeTarget::TypeOrConstParam(id) => {
                         match &params.type_or_consts[*id].name() {
-                            Some(name) => w!(this, "{}", name.display(self.db)),
+                            Some(name) => w!(this, "{}", name.display(self.db.upcast())),
                             None => w!(this, "_anon_{}", id.into_raw()),
                         }
                     }

crates/hir-def/src/lang_item.rs

@@ -2,6 +2,7 @@
 //!
 //! This attribute to tell the compiler about semi built-in std library
 //! features, such as Fn family of traits.
+use hir_expand::name::Name;
 use rustc_hash::FxHashMap;
 use syntax::SmolStr;
 use triomphe::Arc;
@@ -238,7 +239,17 @@ impl LangItem {
 
     pub fn path(&self, db: &dyn DefDatabase, start_crate: CrateId) -> Option<Path> {
         let t = db.lang_item(start_crate, *self)?;
-        Some(Path::LangItem(t))
+        Some(Path::LangItem(t, None))
+    }
+
+    pub fn ty_rel_path(
+        &self,
+        db: &dyn DefDatabase,
+        start_crate: CrateId,
+        seg: Name,
+    ) -> Option<Path> {
+        let t = db.lang_item(start_crate, *self)?;
+        Some(Path::LangItem(t, Some(seg)))
     }
 }
 

crates/hir-def/src/lower.rs

@@ -1,10 +1,11 @@
 //! Context for lowering paths.
+use std::cell::OnceCell;
+
 use hir_expand::{
     ast_id_map::{AstIdMap, AstIdNode},
     hygiene::Hygiene,
     AstId, HirFileId, InFile,
 };
-use once_cell::unsync::OnceCell;
 use syntax::ast;
 use triomphe::Arc;
 

crates/hir-def/src/macro_expansion_tests/builtin_fn_macro.rs

@@ -22,6 +22,45 @@ fn main() { 0 as u32; }
     );
 }
 
+#[test]
+fn test_asm_expand() {
+    check(
+        r#"
+#[rustc_builtin_macro]
+macro_rules! asm {() => {}}
+
+fn main() {
+    let i: u64 = 3;
+    let o: u64;
+    unsafe {
+        asm!(
+            "mov {0}, {1}",
+            "add {0}, 5",
+            out(reg) o,
+            in(reg) i,
+        );
+    }
+}
+"#,
+        expect![[r##"
+#[rustc_builtin_macro]
+macro_rules! asm {() => {}}
+
+fn main() {
+    let i: u64 = 3;
+    let o: u64;
+    unsafe {
+        builtin #asm ( {
+            $crate::format_args!("mov {0}, {1}");
+            $crate::format_args!("add {0}, 5");
+        }
+        );
+    }
+}
+"##]],
+    );
+}
+
 #[test]
 fn test_line_expand() {
     check(
@@ -201,7 +240,7 @@ macro_rules! format_args {
 }
 
 fn main() {
-    ::core::fmt::Arguments::new_v1(&["", " ", ], &[::core::fmt::ArgumentV1::new(&(arg1(a, b, c)), ::core::fmt::Display::fmt), ::core::fmt::ArgumentV1::new(&(arg2), ::core::fmt::Debug::fmt), ]);
+    builtin #format_args ("{} {:?}", arg1(a, b, c), arg2);
 }
 "##]],
     );
@@ -219,10 +258,10 @@ macro_rules! format_args {
 
 fn main() {
     format_args!(x = 2);
-    format_args!(x =);
+    format_args!/*+errors*/(x =);
-    format_args!(x =, x = 2);
+    format_args!/*+errors*/(x =, x = 2);
-    format_args!("{}", x =);
+    format_args!/*+errors*/("{}", x =);
-    format_args!(=, "{}", x =);
+    format_args!/*+errors*/(=, "{}", x =);
     format_args!(x = 2, "{}", 5);
 }
 "#,
@@ -234,12 +273,19 @@ macro_rules! format_args {
 }
 
 fn main() {
-    /* error: no rule matches input tokens */;
+    builtin #format_args (x = 2);
-    /* error: expected expression */;
+    /* parse error: expected expression */
-    /* error: expected expression, expected COMMA */;
+builtin #format_args (x = );
-    /* error: expected expression */::core::fmt::Arguments::new_v1(&["", ], &[::core::fmt::ArgumentV1::new(&(), ::core::fmt::Display::fmt), ]);
+    /* parse error: expected expression */
-    /* error: expected expression, expected R_PAREN */;
+/* parse error: expected R_PAREN */
-    ::core::fmt::Arguments::new_v1(&["", ], &[::core::fmt::ArgumentV1::new(&(5), ::core::fmt::Display::fmt), ]);
+/* parse error: expected expression, item or let statement */
+builtin #format_args (x = , x = 2);
+    /* parse error: expected expression */
+builtin #format_args ("{}", x = );
+    /* parse error: expected expression */
+/* parse error: expected expression */
+builtin #format_args ( = , "{}", x = );
+    builtin #format_args (x = 2, "{}", 5);
 }
 "##]],
     );
@@ -267,7 +313,7 @@ macro_rules! format_args {
 }
 
 fn main() {
-    ::core::fmt::Arguments::new_v1(&["", " ", ], &[::core::fmt::ArgumentV1::new(&(a::<A, B>()), ::core::fmt::Display::fmt), ::core::fmt::ArgumentV1::new(&(b), ::core::fmt::Debug::fmt), ]);
+    builtin #format_args ("{} {:?}", a::<A, B>(), b);
 }
 "##]],
     );
@@ -300,7 +346,7 @@ macro_rules! format_args {
 }
 
 fn main() {
-    ::core::fmt::Arguments::new_v1(&[r#""#, r#",mismatch,""#, r#"",""#, r#"""#, ], &[::core::fmt::ArgumentV1::new(&(location_csv_pat(db, &analysis, vfs, &sm, pat_id)), ::core::fmt::Display::fmt), ::core::fmt::ArgumentV1::new(&(mismatch.expected.display(db)), ::core::fmt::Display::fmt), ::core::fmt::ArgumentV1::new(&(mismatch.actual.display(db)), ::core::fmt::Display::fmt), ]);
+    builtin #format_args (r#"{},mismatch,"{}","{}""#, location_csv_pat(db, &analysis, vfs, &sm, pat_id), mismatch.expected.display(db), mismatch.actual.display(db));
 }
 "##]],
     );
@@ -334,7 +380,7 @@ macro_rules! format_args {
 }
 
 fn main() {
-    ::core::fmt::Arguments::new_v1(&["xxx", "y", "zzz", ], &[::core::fmt::ArgumentV1::new(&(2), ::core::fmt::Display::fmt), ::core::fmt::ArgumentV1::new(&(b), ::core::fmt::Debug::fmt), ]);
+    builtin #format_args (concat!("xxx{}y", "{:?}zzz"), 2, b);
 }
 "##]],
     );
@@ -364,8 +410,8 @@ macro_rules! format_args {
 
 fn main() {
     let _ =
-        /* error: expected field name or number *//* parse error: expected field name or number */
+        /* parse error: expected field name or number */
-::core::fmt::Arguments::new_v1(&["", " ", ], &[::core::fmt::ArgumentV1::new(&(a.), ::core::fmt::Display::fmt), ::core::fmt::ArgumentV1::new(&(), ::core::fmt::Debug::fmt), ]);
+builtin #format_args ("{} {:?}", a.);
 }
 "##]],
     );

crates/hir-def/src/macro_expansion_tests/mbe.rs

@@ -117,7 +117,7 @@ fn main(foo: ()) {
 macro_rules! format_args {}
 
 fn main(foo: ()) {
-    /* error: unresolved macro identity */::core::fmt::Arguments::new_v1(&["", " ", " ", ], &[::core::fmt::ArgumentV1::new(&(::core::fmt::Arguments::new_v1(&["", ], &[::core::fmt::ArgumentV1::new(&(0), ::core::fmt::Display::fmt), ])), ::core::fmt::Display::fmt), ::core::fmt::ArgumentV1::new(&(foo), ::core::fmt::Display::fmt), ::core::fmt::ArgumentV1::new(&(identity!(10)), ::core::fmt::Display::fmt), ])
+    builtin #format_args ("{} {} {}", format_args!("{}", 0), foo, identity!(10), "bar")
 }
 "##]],
     );
@@ -150,8 +150,8 @@ macro_rules! identity {
 }
 
 fn main(foo: ()) {
-    // format_args/*+tokenids*/!("{} {} {}"#1,#3 format_args!("{}", 0#10),#12 foo#13,#14 identity!(10#18),#21 "bar"#22)
+    // format_args/*+tokenids*/!("{} {} {}"#1,#2 format_args#3!#4("{}"#6,#7 0#8),#9 foo#10,#11 identity#12!#13(10#15),#16 "bar"#17)
-::core#4294967295::fmt#4294967295::Arguments#4294967295::new_v1#4294967295(&#4294967295[#4294967295""#4294967295,#4294967295 " "#4294967295,#4294967295 " "#4294967295,#4294967295 ]#4294967295,#4294967295 &#4294967295[::core#4294967295::fmt#4294967295::ArgumentV1#4294967295::new#4294967295(&#4294967295(::core#4294967295::fmt#4294967295::Arguments#4294967295::new_v1#4294967295(&#4294967295[#4294967295""#4294967295,#4294967295 ]#4294967295,#4294967295 &#4294967295[::core#4294967295::fmt#4294967295::ArgumentV1#4294967295::new#4294967295(&#4294967295(#42949672950#10)#4294967295,#4294967295 ::core#4294967295::fmt#4294967295::Display#4294967295::fmt#4294967295)#4294967295,#4294967295 ]#4294967295)#4294967295)#4294967295,#4294967295 ::core#4294967295::fmt#4294967295::Display#4294967295::fmt#4294967295)#4294967295,#4294967295 ::core#4294967295::fmt#4294967295::ArgumentV1#4294967295::new#4294967295(&#4294967295(#4294967295foo#13)#4294967295,#4294967295 ::core#4294967295::fmt#4294967295::Display#4294967295::fmt#4294967295)#4294967295,#4294967295 ::core#4294967295::fmt#4294967295::ArgumentV1#4294967295::new#4294967295(&#4294967295(#429496729510#18)#4294967295,#4294967295 ::core#4294967295::fmt#4294967295::Display#4294967295::fmt#4294967295)#4294967295,#4294967295 ]#4294967295)#4294967295
+builtin#4294967295 ##4294967295format_args#4294967295 (#0"{} {} {}"#1,#2 format_args#3!#4(#5"{}"#6,#7 0#8)#5,#9 foo#10,#11 identity#12!#13(#1410#15)#14,#16 "bar"#17)#0
 }
 
 "##]],

crates/hir-def/src/macro_expansion_tests/mbe/regression.rs

@@ -929,8 +929,8 @@ fn main() {
 macro_rules! format_args {}
 
 fn main() {
-    /* error: expected field name or number *//* parse error: expected field name or number */
+    /* parse error: expected field name or number */
-::core::fmt::Arguments::new_v1(&["", ], &[::core::fmt::ArgumentV1::new(&(line.1.), ::core::fmt::Display::fmt), ]);
+builtin #format_args ("{}", line.1.);
 }
 
 "##]],
@@ -956,19 +956,15 @@ fn main() {
 macro_rules! format_args {}
 
 fn main() {
-    /* error: expected COMMA, expected R_BRACK, expected COMMA, expected COMMA, expected expression, expected R_PAREN *//* parse error: expected COMMA */
+    /* parse error: expected COMMA */
 /* parse error: expected R_BRACK */
 /* parse error: expected COMMA */
 /* parse error: expected COMMA */
 /* parse error: expected expression */
 /* parse error: expected R_PAREN */
-/* parse error: expected R_PAREN */
 /* parse error: expected expression, item or let statement */
 /* parse error: expected expression, item or let statement */
-/* parse error: expected expression, item or let statement */
+builtin #format_args ("{}", &[0 2]);
-/* parse error: expected expression, item or let statement */
-/* parse error: expected expression, item or let statement */
-::core::fmt::Arguments::new_v1(&["", ], &[::core::fmt::ArgumentV1::new(&(&[0 2]), ::core::fmt::Display::fmt), ]);
 }
 
 "##]],

crates/hir-def/src/nameres.rs

@@ -93,7 +93,7 @@ use crate::{
 #[derive(Debug, PartialEq, Eq)]
 pub struct DefMap {
     _c: Count<Self>,
-    /// When this is a block def map, this will hold the block id of the the block and module that
+    /// When this is a block def map, this will hold the block id of the block and module that
     /// contains this block.
     block: Option<BlockInfo>,
     /// The modules and their data declared in this crate.

crates/hir-def/src/nameres/collector.rs

@@ -1828,7 +1828,11 @@ impl ModCollector<'_, '_> {
             let Some(paths) = attr.parse_path_comma_token_tree(db.upcast(), &hygiene) else {
                 // `#[macro_use]` (without any paths) found, forget collected names and just import
                 // all visible macros.
-                self.def_collector.import_macros_from_extern_crate(target_crate, None, Some(extern_crate_id));
+                self.def_collector.import_macros_from_extern_crate(
+                    target_crate,
+                    None,
+                    Some(extern_crate_id),
+                );
                 return;
             };
             for path in paths {

crates/hir-def/src/path.rs

@@ -47,7 +47,7 @@ pub enum Path {
     },
     /// A link to a lang item. It is used in desugaring of things like `it?`. We can show these
     /// links via a normal path since they might be private and not accessible in the usage place.
-    LangItem(LangItemTarget),
+    LangItem(LangItemTarget, Option<Name>),
 }
 
 /// Generic arguments to a path segment (e.g. the `i32` in `Option<i32>`). This
@@ -122,33 +122,40 @@ impl Path {
     pub fn kind(&self) -> &PathKind {
         match self {
             Path::Normal { mod_path, .. } => &mod_path.kind,
-            Path::LangItem(_) => &PathKind::Abs,
+            Path::LangItem(..) => &PathKind::Abs,
         }
     }
 
     pub fn type_anchor(&self) -> Option<&TypeRef> {
         match self {
             Path::Normal { type_anchor, .. } => type_anchor.as_deref(),
-            Path::LangItem(_) => None,
+            Path::LangItem(..) => None,
         }
     }
 
     pub fn segments(&self) -> PathSegments<'_> {
-        let Path::Normal { mod_path, generic_args, .. } = self else {
+        match self {
-            return PathSegments { segments: &[], generic_args: None };
+            Path::Normal { mod_path, generic_args, .. } => {
-        };
+                let s = PathSegments {
-        let s =
+                    segments: mod_path.segments(),
-            PathSegments { segments: mod_path.segments(), generic_args: generic_args.as_deref() };
+                    generic_args: generic_args.as_deref(),
-        if let Some(generic_args) = s.generic_args {
+                };
-            assert_eq!(s.segments.len(), generic_args.len());
+                if let Some(generic_args) = s.generic_args {
+                    assert_eq!(s.segments.len(), generic_args.len());
+                }
+                s
+            }
+            Path::LangItem(_, seg) => PathSegments {
+                segments: seg.as_ref().map_or(&[], |seg| std::slice::from_ref(seg)),
+                generic_args: None,
+            },
         }
-        s
     }
 
     pub fn mod_path(&self) -> Option<&ModPath> {
         match self {
             Path::Normal { mod_path, .. } => Some(&mod_path),
-            Path::LangItem(_) => None,
+            Path::LangItem(..) => None,
         }
     }
 

crates/hir-def/src/pretty.rs

@@ -2,18 +2,54 @@
 
 use std::fmt::{self, Write};
 
-use hir_expand::{db::ExpandDatabase, mod_path::PathKind};
+use hir_expand::mod_path::PathKind;
 use intern::Interned;
 use itertools::Itertools;
 
 use crate::{
+    db::DefDatabase,
+    lang_item::LangItemTarget,
     path::{GenericArg, GenericArgs, Path},
     type_ref::{Mutability, TraitBoundModifier, TypeBound, TypeRef},
 };
 
-pub(crate) fn print_path(db: &dyn ExpandDatabase, path: &Path, buf: &mut dyn Write) -> fmt::Result {
+pub(crate) fn print_path(db: &dyn DefDatabase, path: &Path, buf: &mut dyn Write) -> fmt::Result {
-    if let Path::LangItem(it) = path {
+    if let Path::LangItem(it, s) = path {
-        return write!(buf, "$lang_item::{it:?}");
+        write!(buf, "builtin#lang(")?;
+        match *it {
+            LangItemTarget::ImplDef(it) => write!(buf, "{it:?}")?,
+            LangItemTarget::EnumId(it) => {
+                write!(buf, "{}", db.enum_data(it).name.display(db.upcast()))?
+            }
+            LangItemTarget::Function(it) => {
+                write!(buf, "{}", db.function_data(it).name.display(db.upcast()))?
+            }
+            LangItemTarget::Static(it) => {
+                write!(buf, "{}", db.static_data(it).name.display(db.upcast()))?
+            }
+            LangItemTarget::Struct(it) => {
+                write!(buf, "{}", db.struct_data(it).name.display(db.upcast()))?
+            }
+            LangItemTarget::Union(it) => {
+                write!(buf, "{}", db.union_data(it).name.display(db.upcast()))?
+            }
+            LangItemTarget::TypeAlias(it) => {
+                write!(buf, "{}", db.type_alias_data(it).name.display(db.upcast()))?
+            }
+            LangItemTarget::Trait(it) => {
+                write!(buf, "{}", db.trait_data(it).name.display(db.upcast()))?
+            }
+            LangItemTarget::EnumVariant(it) => write!(
+                buf,
+                "{}",
+                db.enum_data(it.parent).variants[it.local_id].name.display(db.upcast())
+            )?,
+        }
+
+        if let Some(s) = s {
+            write!(buf, "::{}", s.display(db.upcast()))?;
+        }
+        return write!(buf, ")");
     }
     match path.type_anchor() {
         Some(anchor) => {
@@ -44,7 +80,7 @@ pub(crate) fn print_path(db: &dyn ExpandDatabase, path: &Path, buf: &mut dyn Wri
             write!(buf, "::")?;
         }
 
-        write!(buf, "{}", segment.name.display(db))?;
+        write!(buf, "{}", segment.name.display(db.upcast()))?;
         if let Some(generics) = segment.args_and_bindings {
             write!(buf, "::<")?;
             print_generic_args(db, generics, buf)?;
@@ -57,7 +93,7 @@ pub(crate) fn print_path(db: &dyn ExpandDatabase, path: &Path, buf: &mut dyn Wri
 }
 
 pub(crate) fn print_generic_args(
-    db: &dyn ExpandDatabase,
+    db: &dyn DefDatabase,
     generics: &GenericArgs,
     buf: &mut dyn Write,
 ) -> fmt::Result {
@@ -83,7 +119,7 @@ pub(crate) fn print_generic_args(
             write!(buf, ", ")?;
         }
         first = false;
-        write!(buf, "{}", binding.name.display(db))?;
+        write!(buf, "{}", binding.name.display(db.upcast()))?;
         if !binding.bounds.is_empty() {
             write!(buf, ": ")?;
             print_type_bounds(db, &binding.bounds, buf)?;
@@ -97,19 +133,19 @@ pub(crate) fn print_generic_args(
 }
 
 pub(crate) fn print_generic_arg(
-    db: &dyn ExpandDatabase,
+    db: &dyn DefDatabase,
     arg: &GenericArg,
     buf: &mut dyn Write,
 ) -> fmt::Result {
     match arg {
         GenericArg::Type(ty) => print_type_ref(db, ty, buf),
-        GenericArg::Const(c) => write!(buf, "{}", c.display(db)),
+        GenericArg::Const(c) => write!(buf, "{}", c.display(db.upcast())),
-        GenericArg::Lifetime(lt) => write!(buf, "{}", lt.name.display(db)),
+        GenericArg::Lifetime(lt) => write!(buf, "{}", lt.name.display(db.upcast())),
     }
 }
 
 pub(crate) fn print_type_ref(
-    db: &dyn ExpandDatabase,
+    db: &dyn DefDatabase,
     type_ref: &TypeRef,
     buf: &mut dyn Write,
 ) -> fmt::Result {
@@ -143,7 +179,7 @@ pub(crate) fn print_type_ref(
             };
             write!(buf, "&")?;
             if let Some(lt) = lt {
-                write!(buf, "{} ", lt.name.display(db))?;
+                write!(buf, "{} ", lt.name.display(db.upcast()))?;
             }
             write!(buf, "{mtbl}")?;
             print_type_ref(db, pointee, buf)?;
@@ -151,7 +187,7 @@ pub(crate) fn print_type_ref(
         TypeRef::Array(elem, len) => {
             write!(buf, "[")?;
             print_type_ref(db, elem, buf)?;
-            write!(buf, "; {}]", len.display(db))?;
+            write!(buf, "; {}]", len.display(db.upcast()))?;
         }
         TypeRef::Slice(elem) => {
             write!(buf, "[")?;
@@ -198,7 +234,7 @@ pub(crate) fn print_type_ref(
 }
 
 pub(crate) fn print_type_bounds(
-    db: &dyn ExpandDatabase,
+    db: &dyn DefDatabase,
     bounds: &[Interned<TypeBound>],
     buf: &mut dyn Write,
 ) -> fmt::Result {
@@ -216,10 +252,14 @@ pub(crate) fn print_type_bounds(
                 print_path(db, path, buf)?;
             }
             TypeBound::ForLifetime(lifetimes, path) => {
-                write!(buf, "for<{}> ", lifetimes.iter().map(|it| it.display(db)).format(", "))?;
+                write!(
+                    buf,
+                    "for<{}> ",
+                    lifetimes.iter().map(|it| it.display(db.upcast())).format(", ")
+                )?;
                 print_path(db, path, buf)?;
             }
-            TypeBound::Lifetime(lt) => write!(buf, "{}", lt.name.display(db))?,
+            TypeBound::Lifetime(lt) => write!(buf, "{}", lt.name.display(db.upcast()))?,
             TypeBound::Error => write!(buf, "{{unknown}}")?,
         }
     }

crates/hir-def/src/resolver.rs

@@ -156,22 +156,19 @@ impl Resolver {
     ) -> Option<(TypeNs, Option<usize>, Option<ImportOrExternCrate>)> {
         let path = match path {
             Path::Normal { mod_path, .. } => mod_path,
-            Path::LangItem(l) => {
+            Path::LangItem(l, seg) => {
-                return Some((
+                let type_ns = match *l {
-                    match *l {
+                    LangItemTarget::Union(it) => TypeNs::AdtId(it.into()),
-                        LangItemTarget::Union(it) => TypeNs::AdtId(it.into()),
+                    LangItemTarget::TypeAlias(it) => TypeNs::TypeAliasId(it),
-                        LangItemTarget::TypeAlias(it) => TypeNs::TypeAliasId(it),
+                    LangItemTarget::Struct(it) => TypeNs::AdtId(it.into()),
-                        LangItemTarget::Struct(it) => TypeNs::AdtId(it.into()),
+                    LangItemTarget::EnumVariant(it) => TypeNs::EnumVariantId(it),
-                        LangItemTarget::EnumVariant(it) => TypeNs::EnumVariantId(it),
+                    LangItemTarget::EnumId(it) => TypeNs::AdtId(it.into()),
-                        LangItemTarget::EnumId(it) => TypeNs::AdtId(it.into()),
+                    LangItemTarget::Trait(it) => TypeNs::TraitId(it),
-                        LangItemTarget::Trait(it) => TypeNs::TraitId(it),
+                    LangItemTarget::Function(_)
-                        LangItemTarget::Function(_)
+                    | LangItemTarget::ImplDef(_)
-                        | LangItemTarget::ImplDef(_)
+                    | LangItemTarget::Static(_) => return None,
-                        | LangItemTarget::Static(_) => return None,
+                };
-                    },
+                return Some((type_ns, seg.as_ref().map(|_| 1), None));
-                    None,
-                    None,
-                ))
             }
         };
         let first_name = path.segments().first()?;
@@ -256,7 +253,7 @@ impl Resolver {
     ) -> Option<ResolveValueResult> {
         let path = match path {
             Path::Normal { mod_path, .. } => mod_path,
-            Path::LangItem(l) => {
+            Path::LangItem(l, None) => {
                 return Some(ResolveValueResult::ValueNs(
                     match *l {
                         LangItemTarget::Function(it) => ValueNs::FunctionId(it),
@@ -272,6 +269,20 @@ impl Resolver {
                     None,
                 ))
             }
+            Path::LangItem(l, Some(_)) => {
+                let type_ns = match *l {
+                    LangItemTarget::Union(it) => TypeNs::AdtId(it.into()),
+                    LangItemTarget::TypeAlias(it) => TypeNs::TypeAliasId(it),
+                    LangItemTarget::Struct(it) => TypeNs::AdtId(it.into()),
+                    LangItemTarget::EnumVariant(it) => TypeNs::EnumVariantId(it),
+                    LangItemTarget::EnumId(it) => TypeNs::AdtId(it.into()),
+                    LangItemTarget::Trait(it) => TypeNs::TraitId(it),
+                    LangItemTarget::Function(_)
+                    | LangItemTarget::ImplDef(_)
+                    | LangItemTarget::Static(_) => return None,
+                };
+                return Some(ResolveValueResult::Partial(type_ns, 1, None));
+            }
         };
         let n_segments = path.segments().len();
         let tmp = name![self];

crates/hir-expand/src/builtin_fn_macro.rs

@@ -1,13 +1,9 @@
 //! Builtin macro
 
-use std::mem;
-
-use ::tt::Ident;
 use base_db::{AnchoredPath, Edition, FileId};
 use cfg::CfgExpr;
 use either::Either;
 use mbe::{parse_exprs_with_sep, parse_to_token_tree, TokenMap};
-use rustc_hash::FxHashMap;
 use syntax::{
     ast::{self, AstToken},
     SmolStr,
@@ -97,11 +93,11 @@ register_builtin! {
     (unreachable, Unreachable) => unreachable_expand,
     (log_syntax, LogSyntax) => log_syntax_expand,
     (trace_macros, TraceMacros) => trace_macros_expand,
-
-    EAGER:
     (format_args, FormatArgs) => format_args_expand,
     (const_format_args, ConstFormatArgs) => format_args_expand,
     (format_args_nl, FormatArgsNl) => format_args_nl_expand,
+
+    EAGER:
     (compile_error, CompileError) => compile_error_expand,
     (concat, Concat) => concat_expand,
     (concat_idents, ConcatIdents) => concat_idents_expand,
@@ -247,151 +243,15 @@ fn format_args_expand_general(
     _db: &dyn ExpandDatabase,
     _id: MacroCallId,
     tt: &tt::Subtree,
-    end_string: &str,
+    // FIXME: Make use of this so that mir interpretation works properly
+    _end_string: &str,
 ) -> ExpandResult<tt::Subtree> {
-    let args = parse_exprs_with_sep(tt, ',');
+    let pound = quote! {@PUNCT '#'};
-
+    let mut tt = tt.clone();
-    let expand_error =
+    tt.delimiter.kind = tt::DelimiterKind::Parenthesis;
-        ExpandResult::new(tt::Subtree::empty(), mbe::ExpandError::NoMatchingRule.into());
+    return ExpandResult::ok(quote! {
-
+        builtin #pound format_args #tt
-    let mut key_args = FxHashMap::default();
-    let mut args = args.into_iter().filter_map(|mut arg| {
-        // Remove `key =`.
-        if matches!(arg.token_trees.get(1), Some(tt::TokenTree::Leaf(tt::Leaf::Punct(p))) if p.char == '=')
-        {
-            // but not with `==`
-            if !matches!(arg.token_trees.get(2), Some(tt::TokenTree::Leaf(tt::Leaf::Punct(p))) if p.char == '=')
-            {
-                let key = arg.token_trees.drain(..2).next().unwrap();
-                key_args.insert(key.to_string(), arg);
-                return None;
-            }
-        }
-        Some(arg)
-    }).collect::<Vec<_>>().into_iter();
-    // ^^^^^^^ we need this collect, to enforce the side effect of the filter_map closure (building the `key_args`)
-    let Some(format_subtree) = args.next() else {
-        return expand_error;
-    };
-    let format_string = (|| {
-        let token_tree = format_subtree.token_trees.get(0)?;
-        match token_tree {
-            tt::TokenTree::Leaf(l) => match l {
-                tt::Leaf::Literal(l) => {
-                    if let Some(mut text) = l.text.strip_prefix('r') {
-                        let mut raw_sharps = String::new();
-                        while let Some(t) = text.strip_prefix('#') {
-                            text = t;
-                            raw_sharps.push('#');
-                        }
-                        text =
-                            text.strip_suffix(&raw_sharps)?.strip_prefix('"')?.strip_suffix('"')?;
-                        Some((text, l.span, Some(raw_sharps)))
-                    } else {
-                        let text = l.text.strip_prefix('"')?.strip_suffix('"')?;
-                        let span = l.span;
-                        Some((text, span, None))
-                    }
-                }
-                _ => None,
-            },
-            tt::TokenTree::Subtree(_) => None,
-        }
-    })();
-    let Some((format_string, _format_string_span, raw_sharps)) = format_string else {
-        return expand_error;
-    };
-    let mut format_iter = format_string.chars().peekable();
-    let mut parts = vec![];
-    let mut last_part = String::new();
-    let mut arg_tts = vec![];
-    let mut err = None;
-    while let Some(c) = format_iter.next() {
-        // Parsing the format string. See https://doc.rust-lang.org/std/fmt/index.html#syntax for the grammar and more info
-        match c {
-            '{' => {
-                if format_iter.peek() == Some(&'{') {
-                    format_iter.next();
-                    last_part.push('{');
-                    continue;
-                }
-                let mut argument = String::new();
-                while ![Some(&'}'), Some(&':')].contains(&format_iter.peek()) {
-                    argument.push(match format_iter.next() {
-                        Some(c) => c,
-                        None => return expand_error,
-                    });
-                }
-                let format_spec = match format_iter.next().unwrap() {
-                    '}' => "".to_owned(),
-                    ':' => {
-                        let mut s = String::new();
-                        while let Some(c) = format_iter.next() {
-                            if c == '}' {
-                                break;
-                            }
-                            s.push(c);
-                        }
-                        s
-                    }
-                    _ => unreachable!(),
-                };
-                parts.push(mem::take(&mut last_part));
-                let arg_tree = if argument.is_empty() {
-                    match args.next() {
-                        Some(it) => it,
-                        None => {
-                            err = Some(mbe::ExpandError::NoMatchingRule.into());
-                            tt::Subtree::empty()
-                        }
-                    }
-                } else if let Some(tree) = key_args.get(&argument) {
-                    tree.clone()
-                } else {
-                    // FIXME: we should pick the related substring of the `_format_string_span` as the span. You
-                    // can use `.char_indices()` instead of `.char()` for `format_iter` to find the substring interval.
-                    let ident = Ident::new(argument, tt::TokenId::unspecified());
-                    quote!(#ident)
-                };
-                let formatter = match &*format_spec {
-                    "?" => quote!(::core::fmt::Debug::fmt),
-                    "" => quote!(::core::fmt::Display::fmt),
-                    _ => {
-                        // FIXME: implement the rest and return expand error here
-                        quote!(::core::fmt::Display::fmt)
-                    }
-                };
-                arg_tts.push(quote! { ::core::fmt::ArgumentV1::new(&(#arg_tree), #formatter), });
-            }
-            '}' => {
-                if format_iter.peek() == Some(&'}') {
-                    format_iter.next();
-                    last_part.push('}');
-                } else {
-                    return expand_error;
-                }
-            }
-            _ => last_part.push(c),
-        }
-    }
-    last_part += end_string;
-    if !last_part.is_empty() {
-        parts.push(last_part);
-    }
-    let part_tts = parts.into_iter().map(|it| {
-        let text = if let Some(raw) = &raw_sharps {
-            format!("r{raw}\"{}\"{raw}", it).into()
-        } else {
-            format!("\"{}\"", it).into()
-        };
-        let l = tt::Literal { span: tt::TokenId::unspecified(), text };
-        quote!(#l ,)
     });
-    let arg_tts = arg_tts.into_iter().flat_map(|arg| arg.token_trees);
-    let expanded = quote! {
-        ::core::fmt::Arguments::new_v1(&[##part_tts], &[##arg_tts])
-    };
-    ExpandResult { value: expanded, err }
 }
 
 fn asm_expand(
@@ -415,10 +275,12 @@ fn asm_expand(
         }
     }
 
-    let expanded = quote! {{
+    let pound = quote! {@PUNCT '#'};
-        ##literals
+    let expanded = quote! {
-        loop {}
+        builtin #pound asm (
-    }};
+            {##literals}
+        )
+    };
     ExpandResult::ok(expanded)
 }
 
@@ -692,7 +554,7 @@ pub(crate) fn include_arg_to_tt(
     arg_id: MacroCallId,
 ) -> Result<(triomphe::Arc<(::tt::Subtree<::tt::TokenId>, TokenMap)>, FileId), ExpandError> {
     let loc = db.lookup_intern_macro_call(arg_id);
-    let Some(EagerCallInfo { arg,arg_id, .. }) = loc.eager.as_deref() else {
+    let Some(EagerCallInfo { arg, arg_id, .. }) = loc.eager.as_deref() else {
         panic!("include_arg_to_tt called on non include macro call: {:?}", &loc.eager);
     };
     let path = parse_string(&arg.0)?;

crates/hir-expand/src/hygiene.rs

@@ -242,7 +242,7 @@ impl HygieneFrame {
                 krate,
                 call_site: None,
                 def_site: None,
-            }
+            };
         };
 
         let def_site = info.attr_input_or_mac_def_start.map(|it| db.hygiene_frame(it.file_id));

crates/hir-expand/src/name.rs

@@ -54,6 +54,12 @@ impl Name {
         Name(Repr::Text(text))
     }
 
+    // FIXME: See above, unfortunately some places really need this right now
+    #[doc(hidden)]
+    pub const fn new_text_dont_use(text: SmolStr) -> Name {
+        Name(Repr::Text(text))
+    }
+
     pub fn new_tuple_field(idx: usize) -> Name {
         Name(Repr::TupleField(idx))
     }
@@ -302,6 +308,16 @@ pub mod known {
         rust_2018,
         rust_2021,
         v1,
+        new_display,
+        new_debug,
+        new_lower_exp,
+        new_upper_exp,
+        new_octal,
+        new_pointer,
+        new_binary,
+        new_lower_hex,
+        new_upper_hex,
+        from_usize,
         // Components of known path (type name)
         Iterator,
         IntoIterator,
@@ -327,6 +343,13 @@ pub mod known {
         Not,
         None,
         Index,
+        Left,
+        Right,
+        Center,
+        Unknown,
+        Is,
+        Param,
+        Implied,
         // Components of known path (function name)
         filter_map,
         next,
@@ -335,6 +358,8 @@ pub mod known {
         is_empty,
         as_str,
         new,
+        new_v1_formatted,
+        none,
         // Builtin macros
         asm,
         assert,

crates/hir-ty/Cargo.toml

@@ -32,7 +32,8 @@ once_cell = "1.17.0"
 triomphe.workspace = true
 nohash-hasher.workspace = true
 typed-arena = "2.0.1"
-rustc_index = { version = "0.0.20221221", package = "hkalbasi-rustc-ap-rustc_index", default-features = false }
+
+rustc_index.workspace = true
 
 # local deps
 stdx.workspace = true

crates/hir-ty/src/consteval/tests/intrinsics.rs

@@ -499,24 +499,26 @@ fn offset() {
         r#"
         //- minicore: coerce_unsized, index, slice
         extern "rust-intrinsic" {
-            pub fn offset<T>(dst: *const T, offset: isize) -> *const T;
+            pub fn offset<Ptr, Delta>(dst: Ptr, offset: Delta) -> Ptr;
+            pub fn arith_offset<T>(dst: *const T, offset: isize) -> *const T;
         }
 
-        const GOAL: u8 = unsafe {
+        const GOAL: i32 = unsafe {
-            let ar: &[(u8, u8, u8)] = &[
+            let ar: &[(i32, i32, i32)] = &[
                 (10, 11, 12),
                 (20, 21, 22),
                 (30, 31, 32),
                 (40, 41, 42),
                 (50, 51, 52),
             ];
-            let ar: *const [(u8, u8, u8)] = ar;
+            let ar: *const [(i32, i32, i32)] = ar;
-            let ar = ar as *const (u8, u8, u8);
+            let ar = ar as *const (i32, i32, i32);
-            let element = *offset(ar, 2);
+            let element3 = *offset(ar, 2usize);
-            element.1
+            let element4 = *arith_offset(ar, 3);
+            element3.1 * 100 + element4.0
         };
         "#,
-        31,
+        3140,
     );
 }
 
@@ -584,6 +586,24 @@ fn write_bytes() {
     );
 }
 
+#[test]
+fn write_via_move() {
+    check_number(
+        r#"
+        extern "rust-intrinsic" {
+            fn write_via_move<T>(ptr: *mut T, value: T);
+        }
+
+        const GOAL: i32 = unsafe {
+            let mut x = 2;
+            write_via_move(&mut x, 100);
+            x
+        };
+        "#,
+        100,
+    );
+}
+
 #[test]
 fn copy() {
     check_number(

crates/hir-ty/src/diagnostics/decl_check.rs

@@ -163,25 +163,56 @@ impl<'a> DeclValidator<'a> {
                         || allows.contains(allow::NONSTANDARD_STYLE)
                 })
         };
-
+        let db = self.db.upcast();
-        is_allowed(id)
+        let file_id_is_derive = || {
-            // go upwards one step or give up
+            match id {
-            || match id {
+                AttrDefId::ModuleId(m) => {
-                AttrDefId::ModuleId(m) => m.containing_module(self.db.upcast()).map(|v| v.into()),
+                    m.def_map(db)[m.local_id].origin.file_id().map(Into::into)
-                AttrDefId::FunctionId(f) => Some(f.lookup(self.db.upcast()).container.into()),
+                }
-                AttrDefId::StaticId(sid) => Some(sid.lookup(self.db.upcast()).container.into()),
+                AttrDefId::FunctionId(f) => Some(f.lookup(db).id.file_id()),
-                AttrDefId::ConstId(cid) => Some(cid.lookup(self.db.upcast()).container.into()),
+                AttrDefId::StaticId(sid) => Some(sid.lookup(db).id.file_id()),
-                AttrDefId::TraitId(tid) => Some(tid.lookup(self.db.upcast()).container.into()),
+                AttrDefId::ConstId(cid) => Some(cid.lookup(db).id.file_id()),
-                AttrDefId::TraitAliasId(taid) => Some(taid.lookup(self.db.upcast()).container.into()),
+                AttrDefId::TraitId(tid) => Some(tid.lookup(db).id.file_id()),
-                AttrDefId::ImplId(iid) => Some(iid.lookup(self.db.upcast()).container.into()),
+                AttrDefId::TraitAliasId(taid) => Some(taid.lookup(db).id.file_id()),
-                AttrDefId::ExternBlockId(id) => Some(id.lookup(self.db.upcast()).container.into()),
+                AttrDefId::ImplId(iid) => Some(iid.lookup(db).id.file_id()),
-                AttrDefId::ExternCrateId(id) =>  Some(id.lookup(self.db.upcast()).container.into()),
+                AttrDefId::ExternBlockId(id) => Some(id.lookup(db).id.file_id()),
-                AttrDefId::UseId(id) =>  Some(id.lookup(self.db.upcast()).container.into()),
+                AttrDefId::ExternCrateId(id) => Some(id.lookup(db).id.file_id()),
+                AttrDefId::UseId(id) => Some(id.lookup(db).id.file_id()),
                 // These warnings should not explore macro definitions at all
                 AttrDefId::MacroId(_) => None,
                 AttrDefId::AdtId(aid) => match aid {
-                    AdtId::StructId(sid) => Some(sid.lookup(self.db.upcast()).container.into()),
+                    AdtId::StructId(sid) => Some(sid.lookup(db).id.file_id()),
-                    AdtId::EnumId(eid) => Some(eid.lookup(self.db.upcast()).container.into()),
+                    AdtId::EnumId(eid) => Some(eid.lookup(db).id.file_id()),
+                    // Unions aren't yet supported
+                    AdtId::UnionId(_) => None,
+                },
+                AttrDefId::FieldId(_) => None,
+                AttrDefId::EnumVariantId(_) => None,
+                AttrDefId::TypeAliasId(_) => None,
+                AttrDefId::GenericParamId(_) => None,
+            }
+            .map_or(false, |file_id| {
+                file_id.is_custom_derive(db.upcast()) || file_id.is_builtin_derive(db.upcast())
+            })
+        };
+
+        let parent = || {
+            match id {
+                AttrDefId::ModuleId(m) => m.containing_module(db).map(|v| v.into()),
+                AttrDefId::FunctionId(f) => Some(f.lookup(db).container.into()),
+                AttrDefId::StaticId(sid) => Some(sid.lookup(db).container.into()),
+                AttrDefId::ConstId(cid) => Some(cid.lookup(db).container.into()),
+                AttrDefId::TraitId(tid) => Some(tid.lookup(db).container.into()),
+                AttrDefId::TraitAliasId(taid) => Some(taid.lookup(db).container.into()),
+                AttrDefId::ImplId(iid) => Some(iid.lookup(db).container.into()),
+                AttrDefId::ExternBlockId(id) => Some(id.lookup(db).container.into()),
+                AttrDefId::ExternCrateId(id) => Some(id.lookup(db).container.into()),
+                AttrDefId::UseId(id) => Some(id.lookup(db).container.into()),
+                // These warnings should not explore macro definitions at all
+                AttrDefId::MacroId(_) => None,
+                AttrDefId::AdtId(aid) => match aid {
+                    AdtId::StructId(sid) => Some(sid.lookup(db).container.into()),
+                    AdtId::EnumId(eid) => Some(eid.lookup(db).container.into()),
                     // Unions aren't yet supported
                     AdtId::UnionId(_) => None,
                 },
@@ -191,6 +222,12 @@ impl<'a> DeclValidator<'a> {
                 AttrDefId::GenericParamId(_) => None,
             }
             .is_some_and(|mid| self.allowed(mid, allow_name, true))
+        };
+        is_allowed(id)
+            // FIXME: this is a hack to avoid false positives in derive macros currently
+            || file_id_is_derive()
+            // go upwards one step or give up
+            || parent()
     }
 
     fn validate_func(&mut self, func: FunctionId) {

crates/hir-ty/src/infer.rs

@@ -194,7 +194,8 @@ pub(crate) type InferResult<T> = Result<InferOk<T>, TypeError>;
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub enum InferenceDiagnostic {
     NoSuchField {
-        expr: ExprId,
+        field: ExprOrPatId,
+        private: bool,
     },
     PrivateField {
         expr: ExprId,
@@ -228,6 +229,11 @@ pub enum InferenceDiagnostic {
         expected: usize,
         found: usize,
     },
+    MismatchedTupleStructPatArgCount {
+        pat: ExprOrPatId,
+        expected: usize,
+        found: usize,
+    },
     ExpectedFunction {
         call_expr: ExprId,
         found: Ty,

crates/hir-ty/src/infer/cast.rs

@@ -39,8 +39,14 @@ impl CastCheck {
 }
 
 fn check_ref_to_ptr_cast(expr_ty: Ty, cast_ty: Ty, table: &mut InferenceTable<'_>) -> bool {
-    let Some((expr_inner_ty, _, _)) = expr_ty.as_reference() else { return false; };
+    let Some((expr_inner_ty, _, _)) = expr_ty.as_reference() else {
-    let Some((cast_inner_ty, _)) = cast_ty.as_raw_ptr() else { return false; };
+        return false;
-    let TyKind::Array(expr_elt_ty, _) = expr_inner_ty.kind(Interner) else { return false; };
+    };
+    let Some((cast_inner_ty, _)) = cast_ty.as_raw_ptr() else {
+        return false;
+    };
+    let TyKind::Array(expr_elt_ty, _) = expr_inner_ty.kind(Interner) else {
+        return false;
+    };
     table.coerce(expr_elt_ty, cast_inner_ty).is_ok()
 }

crates/hir-ty/src/infer/closure.rs

@@ -452,6 +452,8 @@ impl InferenceContext<'_> {
 
     fn walk_expr_without_adjust(&mut self, tgt_expr: ExprId) {
         match &self.body[tgt_expr] {
+            Expr::OffsetOf(_) => (),
+            Expr::InlineAsm(e) => self.walk_expr_without_adjust(e.e),
             Expr::If { condition, then_branch, else_branch } => {
                 self.consume_expr(*condition);
                 self.consume_expr(*then_branch);
@@ -467,13 +469,13 @@ impl InferenceContext<'_> {
                         Statement::Let { pat, type_ref: _, initializer, else_branch } => {
                             if let Some(else_branch) = else_branch {
                                 self.consume_expr(*else_branch);
-                                if let Some(initializer) = initializer {
-                                    self.consume_expr(*initializer);
-                                }
-                                return;
                             }
                             if let Some(initializer) = initializer {
-                                self.walk_expr(*initializer);
+                                if else_branch.is_some() {
+                                    self.consume_expr(*initializer);
+                                } else {
+                                    self.walk_expr(*initializer);
+                                }
                                 if let Some(place) = self.place_of_expr(*initializer) {
                                     self.consume_with_pat(place, *pat);
                                 }
@@ -620,6 +622,7 @@ impl InferenceContext<'_> {
             | Expr::Tuple { exprs, is_assignee_expr: _ } => {
                 self.consume_exprs(exprs.iter().copied())
             }
+
             Expr::Missing
             | Expr::Continue { .. }
             | Expr::Path(_)

crates/hir-ty/src/infer/expr.rs

@@ -514,9 +514,6 @@ impl InferenceContext<'_> {
             }
             Expr::RecordLit { path, fields, spread, .. } => {
                 let (ty, def_id) = self.resolve_variant(path.as_deref(), false);
-                if let Some(variant) = def_id {
-                    self.write_variant_resolution(tgt_expr.into(), variant);
-                }
 
                 if let Some(t) = expected.only_has_type(&mut self.table) {
                     self.unify(&ty, &t);
@@ -526,26 +523,56 @@ impl InferenceContext<'_> {
                     .as_adt()
                     .map(|(_, s)| s.clone())
                     .unwrap_or_else(|| Substitution::empty(Interner));
-                let field_types = def_id.map(|it| self.db.field_types(it)).unwrap_or_default();
+                if let Some(variant) = def_id {
-                let variant_data = def_id.map(|it| it.variant_data(self.db.upcast()));
+                    self.write_variant_resolution(tgt_expr.into(), variant);
-                for field in fields.iter() {
+                }
-                    let field_def =
+                match def_id {
-                        variant_data.as_ref().and_then(|it| match it.field(&field.name) {
+                    _ if fields.is_empty() => {}
-                            Some(local_id) => Some(FieldId { parent: def_id.unwrap(), local_id }),
+                    Some(def) => {
-                            None => {
+                        let field_types = self.db.field_types(def);
-                                self.push_diagnostic(InferenceDiagnostic::NoSuchField {
+                        let variant_data = def.variant_data(self.db.upcast());
-                                    expr: field.expr,
+                        let visibilities = self.db.field_visibilities(def);
-                                });
+                        for field in fields.iter() {
-                                None
+                            let field_def = {
-                            }
+                                match variant_data.field(&field.name) {
-                        });
+                                    Some(local_id) => {
-                    let field_ty = field_def.map_or(self.err_ty(), |it| {
+                                        if !visibilities[local_id].is_visible_from(
-                        field_types[it.local_id].clone().substitute(Interner, &substs)
+                                            self.db.upcast(),
-                    });
+                                            self.resolver.module(),
-                    // Field type might have some unknown types
+                                        ) {
-                    // FIXME: we may want to emit a single type variable for all instance of type fields?
+                                            self.push_diagnostic(
-                    let field_ty = self.insert_type_vars(field_ty);
+                                                InferenceDiagnostic::NoSuchField {
-                    self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty));
+                                                    field: field.expr.into(),
+                                                    private: true,
+                                                },
+                                            );
+                                        }
+                                        Some(local_id)
+                                    }
+                                    None => {
+                                        self.push_diagnostic(InferenceDiagnostic::NoSuchField {
+                                            field: field.expr.into(),
+                                            private: false,
+                                        });
+                                        None
+                                    }
+                                }
+                            };
+                            let field_ty = field_def.map_or(self.err_ty(), |it| {
+                                field_types[it].clone().substitute(Interner, &substs)
+                            });
+
+                            // Field type might have some unknown types
+                            // FIXME: we may want to emit a single type variable for all instance of type fields?
+                            let field_ty = self.insert_type_vars(field_ty);
+                            self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty));
+                        }
+                    }
+                    None => {
+                        for field in fields.iter() {
+                            self.infer_expr_coerce(field.expr, &Expectation::None);
+                        }
+                    }
                 }
                 if let Some(expr) = spread {
                     self.infer_expr(*expr, &Expectation::has_type(ty.clone()));
@@ -843,6 +870,11 @@ impl InferenceContext<'_> {
                 });
                 expected
             }
+            Expr::OffsetOf(_) => TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(Interner),
+            Expr::InlineAsm(it) => {
+                self.infer_expr_no_expect(it.e);
+                self.result.standard_types.unit.clone()
+            }
         };
         // use a new type variable if we got unknown here
         let ty = self.insert_type_vars_shallow(ty);
@@ -1122,7 +1154,7 @@ impl InferenceContext<'_> {
             Expr::Underscore => rhs_ty.clone(),
             _ => {
                 // `lhs` is a place expression, a unit struct, or an enum variant.
-                let lhs_ty = self.infer_expr(lhs, &Expectation::none());
+                let lhs_ty = self.infer_expr_inner(lhs, &Expectation::none());
 
                 // This is the only branch where this function may coerce any type.
                 // We are returning early to avoid the unifiability check below.

crates/hir-ty/src/infer/mutability.rs

@@ -35,6 +35,8 @@ impl InferenceContext<'_> {
     fn infer_mut_expr_without_adjust(&mut self, tgt_expr: ExprId, mutability: Mutability) {
         match &self.body[tgt_expr] {
             Expr::Missing => (),
+            Expr::InlineAsm(e) => self.infer_mut_expr_without_adjust(e.e, Mutability::Not),
+            Expr::OffsetOf(_) => (),
             &Expr::If { condition, then_branch, else_branch } => {
                 self.infer_mut_expr(condition, Mutability::Not);
                 self.infer_mut_expr(then_branch, Mutability::Not);

crates/hir-ty/src/infer/pat.rs

@@ -15,7 +15,8 @@ use crate::{
     infer::{BindingMode, Expectation, InferenceContext, TypeMismatch},
     lower::lower_to_chalk_mutability,
     primitive::UintTy,
-    static_lifetime, Interner, Scalar, Substitution, Ty, TyBuilder, TyExt, TyKind,
+    static_lifetime, InferenceDiagnostic, Interner, Scalar, Substitution, Ty, TyBuilder, TyExt,
+    TyKind,
 };
 
 /// Used to generalize patterns and assignee expressions.
@@ -74,29 +75,68 @@ impl InferenceContext<'_> {
         if let Some(variant) = def {
             self.write_variant_resolution(id.into(), variant);
         }
+        if let Some(var) = &var_data {
+            let cmp = if ellipsis.is_some() { usize::gt } else { usize::ne };
+
+            if cmp(&subs.len(), &var.fields().len()) {
+                self.push_diagnostic(InferenceDiagnostic::MismatchedTupleStructPatArgCount {
+                    pat: id.into(),
+                    expected: var.fields().len(),
+                    found: subs.len(),
+                });
+            }
+        }
+
         self.unify(&ty, expected);
 
         let substs =
             ty.as_adt().map(|(_, s)| s.clone()).unwrap_or_else(|| Substitution::empty(Interner));
 
-        let field_tys = def.map(|it| self.db.field_types(it)).unwrap_or_default();
+        match def {
-        let (pre, post) = match ellipsis {
+            _ if subs.len() == 0 => {}
-            Some(idx) => subs.split_at(idx),
+            Some(def) => {
-            None => (subs, &[][..]),
+                let field_types = self.db.field_types(def);
-        };
+                let variant_data = def.variant_data(self.db.upcast());
-        let post_idx_offset = field_tys.iter().count().saturating_sub(post.len());
+                let visibilities = self.db.field_visibilities(def);
 
-        let pre_iter = pre.iter().enumerate();
+                let (pre, post) = match ellipsis {
-        let post_iter = (post_idx_offset..).zip(post.iter());
+                    Some(idx) => subs.split_at(idx),
-        for (i, &subpat) in pre_iter.chain(post_iter) {
+                    None => (subs, &[][..]),
-            let expected_ty = var_data
+                };
-                .as_ref()
+                let post_idx_offset = field_types.iter().count().saturating_sub(post.len());
-                .and_then(|d| d.field(&Name::new_tuple_field(i)))
+
-                .map_or(self.err_ty(), |field| {
+                let pre_iter = pre.iter().enumerate();
-                    field_tys[field].clone().substitute(Interner, &substs)
+                let post_iter = (post_idx_offset..).zip(post.iter());
-                });
+
-            let expected_ty = self.normalize_associated_types_in(expected_ty);
+                for (i, &subpat) in pre_iter.chain(post_iter) {
-            T::infer(self, subpat, &expected_ty, default_bm);
+                    let field_def = {
+                        match variant_data.field(&Name::new_tuple_field(i)) {
+                            Some(local_id) => {
+                                if !visibilities[local_id]
+                                    .is_visible_from(self.db.upcast(), self.resolver.module())
+                                {
+                                    // FIXME(DIAGNOSE): private tuple field
+                                }
+                                Some(local_id)
+                            }
+                            None => None,
+                        }
+                    };
+
+                    let expected_ty = field_def.map_or(self.err_ty(), |f| {
+                        field_types[f].clone().substitute(Interner, &substs)
+                    });
+                    let expected_ty = self.normalize_associated_types_in(expected_ty);
+
+                    T::infer(self, subpat, &expected_ty, default_bm);
+                }
+            }
+            None => {
+                let err_ty = self.err_ty();
+                for &inner in subs {
+                    T::infer(self, inner, &err_ty, default_bm);
+                }
+            }
         }
 
         ty
@@ -109,7 +149,7 @@ impl InferenceContext<'_> {
         expected: &Ty,
         default_bm: T::BindingMode,
         id: T,
-        subs: impl Iterator<Item = (Name, T)>,
+        subs: impl Iterator<Item = (Name, T)> + ExactSizeIterator,
     ) -> Ty {
         let (ty, def) = self.resolve_variant(path, false);
         if let Some(variant) = def {
@@ -121,17 +161,51 @@ impl InferenceContext<'_> {
         let substs =
             ty.as_adt().map(|(_, s)| s.clone()).unwrap_or_else(|| Substitution::empty(Interner));
 
-        let field_tys = def.map(|it| self.db.field_types(it)).unwrap_or_default();
+        match def {
-        let var_data = def.map(|it| it.variant_data(self.db.upcast()));
+            _ if subs.len() == 0 => {}
+            Some(def) => {
+                let field_types = self.db.field_types(def);
+                let variant_data = def.variant_data(self.db.upcast());
+                let visibilities = self.db.field_visibilities(def);
 
-        for (name, inner) in subs {
+                for (name, inner) in subs {
-            let expected_ty = var_data
+                    let field_def = {
-                .as_ref()
+                        match variant_data.field(&name) {
-                .and_then(|it| it.field(&name))
+                            Some(local_id) => {
-                .map_or(self.err_ty(), |f| field_tys[f].clone().substitute(Interner, &substs));
+                                if !visibilities[local_id]
-            let expected_ty = self.normalize_associated_types_in(expected_ty);
+                                    .is_visible_from(self.db.upcast(), self.resolver.module())
+                                {
+                                    self.push_diagnostic(InferenceDiagnostic::NoSuchField {
+                                        field: inner.into(),
+                                        private: true,
+                                    });
+                                }
+                                Some(local_id)
+                            }
+                            None => {
+                                self.push_diagnostic(InferenceDiagnostic::NoSuchField {
+                                    field: inner.into(),
+                                    private: false,
+                                });
+                                None
+                            }
+                        }
+                    };
 
-            T::infer(self, inner, &expected_ty, default_bm);
+                    let expected_ty = field_def.map_or(self.err_ty(), |f| {
+                        field_types[f].clone().substitute(Interner, &substs)
+                    });
+                    let expected_ty = self.normalize_associated_types_in(expected_ty);
+
+                    T::infer(self, inner, &expected_ty, default_bm);
+                }
+            }
+            None => {
+                let err_ty = self.err_ty();
+                for (_, inner) in subs {
+                    T::infer(self, inner, &err_ty, default_bm);
+                }
+            }
         }
 
         ty

crates/hir-ty/src/infer/path.rs

@@ -178,13 +178,30 @@ impl InferenceContext<'_> {
         remaining_index: usize,
         id: ExprOrPatId,
     ) -> Option<(ValueNs, Substitution)> {
-        assert!(remaining_index < path.segments().len());
         // there may be more intermediate segments between the resolved one and
         // the end. Only the last segment needs to be resolved to a value; from
         // the segments before that, we need to get either a type or a trait ref.
 
-        let resolved_segment = path.segments().get(remaining_index - 1).unwrap();
+        let _d;
-        let remaining_segments = path.segments().skip(remaining_index);
+        let (resolved_segment, remaining_segments) = match path {
+            Path::Normal { .. } => {
+                assert!(remaining_index < path.segments().len());
+                (
+                    path.segments().get(remaining_index - 1).unwrap(),
+                    path.segments().skip(remaining_index),
+                )
+            }
+            Path::LangItem(..) => (
+                PathSegment {
+                    name: {
+                        _d = hir_expand::name::known::Unknown;
+                        &_d
+                    },
+                    args_and_bindings: None,
+                },
+                path.segments(),
+            ),
+        };
         let is_before_last = remaining_segments.len() == 1;
 
         match (def, is_before_last) {

crates/hir-ty/src/layout.rs

@@ -24,7 +24,7 @@ pub use self::{
 
 macro_rules! user_error {
     ($it: expr) => {
-        return Err(LayoutError::UserError(format!($it)))
+        return Err(LayoutError::UserError(format!($it).into()))
     };
 }
 
@@ -50,7 +50,7 @@ pub type Variants = hir_def::layout::Variants<RustcEnumVariantIdx>;
 
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub enum LayoutError {
-    UserError(String),
+    UserError(Box<str>),
     SizeOverflow,
     TargetLayoutNotAvailable,
     HasPlaceholder,
@@ -109,7 +109,8 @@ fn layout_of_simd_ty(
     // * the homogeneous field type and the number of fields.
     let (e_ty, e_len, is_array) = if let TyKind::Array(e_ty, _) = f0_ty.kind(Interner) {
         // Extract the number of elements from the layout of the array field:
-        let FieldsShape::Array { count, .. } = db.layout_of_ty(f0_ty.clone(), env.clone())?.fields else {
+        let FieldsShape::Array { count, .. } = db.layout_of_ty(f0_ty.clone(), env.clone())?.fields
+        else {
             user_error!("Array with non array layout");
         };
 
@@ -233,9 +234,9 @@ pub fn layout_of_ty_query(
             cx.univariant(dl, &fields, &ReprOptions::default(), kind).ok_or(LayoutError::Unknown)?
         }
         TyKind::Array(element, count) => {
-            let count = try_const_usize(db, &count).ok_or(LayoutError::UserError(
+            let count = try_const_usize(db, &count).ok_or(LayoutError::UserError(Box::from(
-                "unevaluated or mistyped const generic parameter".to_string(),
+                "unevaluated or mistyped const generic parameter",
-            ))? as u64;
+            )))? as u64;
             let element = db.layout_of_ty(element.clone(), trait_env.clone())?;
             let size = element.size.checked_mul(count, dl).ok_or(LayoutError::SizeOverflow)?;
 

crates/hir-ty/src/layout/adt.rs

@@ -163,7 +163,7 @@ fn repr_discr(
             return Err(LayoutError::UserError(
                 "Integer::repr_discr: `#[repr]` hint too small for \
                       discriminant range of enum "
-                    .to_string(),
+                    .into(),
             ));
         }
         return Ok((discr, ity.is_signed()));

crates/hir-ty/src/layout/tests.rs

@@ -212,14 +212,14 @@ fn recursive() {
     }
     check_fail(
         r#"struct Goal(Goal);"#,
-        LayoutError::UserError("infinite sized recursive type".to_string()),
+        LayoutError::UserError("infinite sized recursive type".into()),
     );
     check_fail(
         r#"
         struct Foo<T>(Foo<T>);
         struct Goal(Foo<i32>);
         "#,
-        LayoutError::UserError("infinite sized recursive type".to_string()),
+        LayoutError::UserError("infinite sized recursive type".into()),
     );
 }
 

crates/hir-ty/src/layout/tests/closure.rs

@@ -255,3 +255,17 @@ fn ellipsis_pattern() {
         }
     }
 }
+
+#[test]
+fn regression_15623() {
+    size_and_align_expr! {
+        let a = 2;
+        let b = 3;
+        let c = 5;
+        move || {
+            let 0 = a else { return b; };
+            let y = c;
+            y
+        }
+    }
+}

crates/hir-ty/src/mir.rs

@@ -1,6 +1,6 @@
 //! MIR definitions and implementation
 
-use std::{fmt::Display, iter};
+use std::{collections::hash_map::Entry, fmt::Display, iter};
 
 use crate::{
     consteval::usize_const,
@@ -37,6 +37,7 @@ pub use monomorphization::{
     monomorphize_mir_body_bad, monomorphized_mir_body_for_closure_query,
     monomorphized_mir_body_query, monomorphized_mir_body_recover,
 };
+use rustc_hash::FxHashMap;
 use smallvec::{smallvec, SmallVec};
 use stdx::{impl_from, never};
 use triomphe::Arc;
@@ -165,8 +166,8 @@ impl<V, T> ProjectionElem<V, T> {
                 TyKind::Adt(_, subst) => {
                     db.field_types(f.parent)[f.local_id].clone().substitute(Interner, subst)
                 }
-                _ => {
+                ty => {
-                    never!("Only adt has field");
+                    never!("Only adt has field, found {:?}", ty);
                     return TyKind::Error.intern(Interner);
                 }
             },
@@ -223,35 +224,93 @@ impl<V, T> ProjectionElem<V, T> {
 
 type PlaceElem = ProjectionElem<LocalId, Ty>;
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ProjectionId(u32);
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ProjectionStore {
+    id_to_proj: FxHashMap<ProjectionId, Box<[PlaceElem]>>,
+    proj_to_id: FxHashMap<Box<[PlaceElem]>, ProjectionId>,
+}
+
+impl Default for ProjectionStore {
+    fn default() -> Self {
+        let mut this = Self { id_to_proj: Default::default(), proj_to_id: Default::default() };
+        // Ensure that [] will get the id 0 which is used in `ProjectionId::Empty`
+        this.intern(Box::new([]));
+        this
+    }
+}
+
+impl ProjectionStore {
+    fn shrink_to_fit(&mut self) {
+        self.id_to_proj.shrink_to_fit();
+        self.proj_to_id.shrink_to_fit();
+    }
+
+    fn intern_if_exist(&self, projection: &[PlaceElem]) -> Option<ProjectionId> {
+        self.proj_to_id.get(projection).copied()
+    }
+
+    fn intern(&mut self, projection: Box<[PlaceElem]>) -> ProjectionId {
+        let new_id = ProjectionId(self.proj_to_id.len() as u32);
+        match self.proj_to_id.entry(projection) {
+            Entry::Occupied(id) => *id.get(),
+            Entry::Vacant(e) => {
+                let key_clone = e.key().clone();
+                e.insert(new_id);
+                self.id_to_proj.insert(new_id, key_clone);
+                new_id
+            }
+        }
+    }
+}
+
+impl ProjectionId {
+    const EMPTY: ProjectionId = ProjectionId(0);
+
+    fn lookup(self, store: &ProjectionStore) -> &[PlaceElem] {
+        store.id_to_proj.get(&self).unwrap()
+    }
+
+    fn project(self, projection: PlaceElem, store: &mut ProjectionStore) -> ProjectionId {
+        let mut current = self.lookup(store).to_vec();
+        current.push(projection);
+        store.intern(current.into())
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Place {
     pub local: LocalId,
-    pub projection: Box<[PlaceElem]>,
+    pub projection: ProjectionId,
 }
 
 impl Place {
-    fn is_parent(&self, child: &Place) -> bool {
+    fn is_parent(&self, child: &Place, store: &ProjectionStore) -> bool {
-        self.local == child.local && child.projection.starts_with(&self.projection)
+        self.local == child.local
+            && child.projection.lookup(store).starts_with(&self.projection.lookup(store))
     }
 
     /// The place itself is not included
-    fn iterate_over_parents(&self) -> impl Iterator<Item = Place> + '_ {
+    fn iterate_over_parents<'a>(
-        (0..self.projection.len())
+        &'a self,
-            .map(|x| &self.projection[0..x])
+        store: &'a ProjectionStore,
-            .map(|x| Place { local: self.local, projection: x.to_vec().into() })
+    ) -> impl Iterator<Item = Place> + 'a {
+        let projection = self.projection.lookup(store);
+        (0..projection.len()).map(|x| &projection[0..x]).filter_map(move |x| {
+            Some(Place { local: self.local, projection: store.intern_if_exist(x)? })
+        })
     }
 
-    fn project(&self, projection: PlaceElem) -> Place {
+    fn project(&self, projection: PlaceElem, store: &mut ProjectionStore) -> Place {
-        Place {
+        Place { local: self.local, projection: self.projection.project(projection, store) }
-            local: self.local,
-            projection: self.projection.iter().cloned().chain([projection]).collect(),
-        }
     }
 }
 
 impl From<LocalId> for Place {
     fn from(local: LocalId) -> Self {
-        Self { local, projection: vec![].into() }
+        Self { local, projection: ProjectionId::EMPTY }
     }
 }
 
@@ -997,6 +1056,7 @@ pub struct BasicBlock {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct MirBody {
+    pub projection_store: ProjectionStore,
     pub basic_blocks: Arena<BasicBlock>,
     pub locals: Arena<Local>,
     pub start_block: BasicBlockId,
@@ -1009,11 +1069,15 @@ pub struct MirBody {
 }
 
 impl MirBody {
-    fn walk_places(&mut self, mut f: impl FnMut(&mut Place)) {
+    fn walk_places(&mut self, mut f: impl FnMut(&mut Place, &mut ProjectionStore)) {
-        fn for_operand(op: &mut Operand, f: &mut impl FnMut(&mut Place)) {
+        fn for_operand(
+            op: &mut Operand,
+            f: &mut impl FnMut(&mut Place, &mut ProjectionStore),
+            store: &mut ProjectionStore,
+        ) {
             match op {
                 Operand::Copy(p) | Operand::Move(p) => {
-                    f(p);
+                    f(p, store);
                 }
                 Operand::Constant(_) | Operand::Static(_) => (),
             }
@@ -1022,30 +1086,30 @@ impl MirBody {
             for statement in &mut block.statements {
                 match &mut statement.kind {
                     StatementKind::Assign(p, r) => {
-                        f(p);
+                        f(p, &mut self.projection_store);
                         match r {
                             Rvalue::ShallowInitBoxWithAlloc(_) => (),
                             Rvalue::ShallowInitBox(o, _)
                             | Rvalue::UnaryOp(_, o)
                             | Rvalue::Cast(_, o, _)
                             | Rvalue::Repeat(o, _)
-                            | Rvalue::Use(o) => for_operand(o, &mut f),
+                            | Rvalue::Use(o) => for_operand(o, &mut f, &mut self.projection_store),
                             Rvalue::CopyForDeref(p)
                             | Rvalue::Discriminant(p)
                             | Rvalue::Len(p)
-                            | Rvalue::Ref(_, p) => f(p),
+                            | Rvalue::Ref(_, p) => f(p, &mut self.projection_store),
                             Rvalue::CheckedBinaryOp(_, o1, o2) => {
-                                for_operand(o1, &mut f);
+                                for_operand(o1, &mut f, &mut self.projection_store);
-                                for_operand(o2, &mut f);
+                                for_operand(o2, &mut f, &mut self.projection_store);
                             }
                             Rvalue::Aggregate(_, ops) => {
                                 for op in ops.iter_mut() {
-                                    for_operand(op, &mut f);
+                                    for_operand(op, &mut f, &mut self.projection_store);
                                 }
                             }
                         }
                     }
-                    StatementKind::Deinit(p) => f(p),
+                    StatementKind::Deinit(p) => f(p, &mut self.projection_store),
                     StatementKind::StorageLive(_)
                     | StatementKind::StorageDead(_)
                     | StatementKind::Nop => (),
@@ -1053,7 +1117,9 @@ impl MirBody {
             }
             match &mut block.terminator {
                 Some(x) => match &mut x.kind {
-                    TerminatorKind::SwitchInt { discr, .. } => for_operand(discr, &mut f),
+                    TerminatorKind::SwitchInt { discr, .. } => {
+                        for_operand(discr, &mut f, &mut self.projection_store)
+                    }
                     TerminatorKind::FalseEdge { .. }
                     | TerminatorKind::FalseUnwind { .. }
                     | TerminatorKind::Goto { .. }
@@ -1063,23 +1129,24 @@ impl MirBody {
                     | TerminatorKind::Return
                     | TerminatorKind::Unreachable => (),
                     TerminatorKind::Drop { place, .. } => {
-                        f(place);
+                        f(place, &mut self.projection_store);
                     }
                     TerminatorKind::DropAndReplace { place, value, .. } => {
-                        f(place);
+                        f(place, &mut self.projection_store);
-                        for_operand(value, &mut f);
+                        for_operand(value, &mut f, &mut self.projection_store);
                     }
                     TerminatorKind::Call { func, args, destination, .. } => {
-                        for_operand(func, &mut f);
+                        for_operand(func, &mut f, &mut self.projection_store);
-                        args.iter_mut().for_each(|x| for_operand(x, &mut f));
+                        args.iter_mut()
-                        f(destination);
+                            .for_each(|x| for_operand(x, &mut f, &mut self.projection_store));
+                        f(destination, &mut self.projection_store);
                     }
                     TerminatorKind::Assert { cond, .. } => {
-                        for_operand(cond, &mut f);
+                        for_operand(cond, &mut f, &mut self.projection_store);
                     }
                     TerminatorKind::Yield { value, resume_arg, .. } => {
-                        for_operand(value, &mut f);
+                        for_operand(value, &mut f, &mut self.projection_store);
-                        f(resume_arg);
+                        f(resume_arg, &mut self.projection_store);
                     }
                 },
                 None => (),
@@ -1096,7 +1163,9 @@ impl MirBody {
             binding_locals,
             param_locals,
             closures,
+            projection_store,
         } = self;
+        projection_store.shrink_to_fit();
         basic_blocks.shrink_to_fit();
         locals.shrink_to_fit();
         binding_locals.shrink_to_fit();

crates/hir-ty/src/mir/borrowck.rs

@@ -42,30 +42,27 @@ pub struct BorrowckResult {
 fn all_mir_bodies(
     db: &dyn HirDatabase,
     def: DefWithBodyId,
-) -> Box<dyn Iterator<Item = Result<Arc<MirBody>, MirLowerError>> + '_> {
+    mut cb: impl FnMut(Arc<MirBody>),
+) -> Result<(), MirLowerError> {
     fn for_closure(
         db: &dyn HirDatabase,
         c: ClosureId,
-    ) -> Box<dyn Iterator<Item = Result<Arc<MirBody>, MirLowerError>> + '_> {
+        cb: &mut impl FnMut(Arc<MirBody>),
+    ) -> Result<(), MirLowerError> {
         match db.mir_body_for_closure(c) {
             Ok(body) => {
-                let closures = body.closures.clone();
+                cb(body.clone());
-                Box::new(
+                body.closures.iter().map(|&it| for_closure(db, it, cb)).collect()
-                    iter::once(Ok(body))
-                        .chain(closures.into_iter().flat_map(|it| for_closure(db, it))),
-                )
             }
-            Err(e) => Box::new(iter::once(Err(e))),
+            Err(e) => Err(e),
         }
     }
     match db.mir_body(def) {
         Ok(body) => {
-            let closures = body.closures.clone();
+            cb(body.clone());
-            Box::new(
+            body.closures.iter().map(|&it| for_closure(db, it, &mut cb)).collect()
-                iter::once(Ok(body)).chain(closures.into_iter().flat_map(|it| for_closure(db, it))),
-            )
         }
-        Err(e) => Box::new(iter::once(Err(e))),
+        Err(e) => Err(e),
     }
 }
 
@@ -74,17 +71,15 @@ pub fn borrowck_query(
     def: DefWithBodyId,
 ) -> Result<Arc<[BorrowckResult]>, MirLowerError> {
     let _p = profile::span("borrowck_query");
-    let r = all_mir_bodies(db, def)
+    let mut res = vec![];
-        .map(|body| {
+    all_mir_bodies(db, def, |body| {
-            let body = body?;
+        res.push(BorrowckResult {
-            Ok(BorrowckResult {
+            mutability_of_locals: mutability_of_locals(db, &body),
-                mutability_of_locals: mutability_of_locals(db, &body),
+            moved_out_of_ref: moved_out_of_ref(db, &body),
-                moved_out_of_ref: moved_out_of_ref(db, &body),
+            mir_body: body,
-                mir_body: body,
+        });
-            })
+    })?;
-        })
+    Ok(res.into())
-        .collect::<Result<Vec<_>, MirLowerError>>()?;
-    Ok(r.into())
 }
 
 fn moved_out_of_ref(db: &dyn HirDatabase, body: &MirBody) -> Vec<MovedOutOfRef> {
@@ -93,7 +88,7 @@ fn moved_out_of_ref(db: &dyn HirDatabase, body: &MirBody) -> Vec<MovedOutOfRef>
         Operand::Copy(p) | Operand::Move(p) => {
             let mut ty: Ty = body.locals[p.local].ty.clone();
             let mut is_dereference_of_ref = false;
-            for proj in &*p.projection {
+            for proj in p.projection.lookup(&body.projection_store) {
                 if *proj == ProjectionElem::Deref && ty.as_reference().is_some() {
                     is_dereference_of_ref = true;
                 }
@@ -125,6 +120,7 @@ fn moved_out_of_ref(db: &dyn HirDatabase, body: &MirBody) -> Vec<MovedOutOfRef>
         Operand::Constant(_) | Operand::Static(_) => (),
     };
     for (_, block) in body.basic_blocks.iter() {
+        db.unwind_if_cancelled();
         for statement in &block.statements {
             match &statement.kind {
                 StatementKind::Assign(_, r) => match r {
@@ -183,6 +179,7 @@ fn moved_out_of_ref(db: &dyn HirDatabase, body: &MirBody) -> Vec<MovedOutOfRef>
             None => (),
         }
     }
+    result.shrink_to_fit();
     result
 }
 
@@ -199,7 +196,7 @@ enum ProjectionCase {
 fn place_case(db: &dyn HirDatabase, body: &MirBody, lvalue: &Place) -> ProjectionCase {
     let mut is_part_of = false;
     let mut ty = body.locals[lvalue.local].ty.clone();
-    for proj in lvalue.projection.iter() {
+    for proj in lvalue.projection.lookup(&body.projection_store).iter() {
         match proj {
             ProjectionElem::Deref if ty.as_adt().is_none() => return ProjectionCase::Indirect, // It's indirect in case of reference and raw
             ProjectionElem::Deref // It's direct in case of `Box<T>`
@@ -258,7 +255,7 @@ fn ever_initialized_map(
         for statement in &block.statements {
             match &statement.kind {
                 StatementKind::Assign(p, _) => {
-                    if p.projection.len() == 0 && p.local == l {
+                    if p.projection.lookup(&body.projection_store).len() == 0 && p.local == l {
                         is_ever_initialized = true;
                     }
                 }
@@ -277,21 +274,37 @@ fn ever_initialized_map(
             );
             return;
         };
-        let targets = match &terminator.kind {
+        let mut process = |target, is_ever_initialized| {
-            TerminatorKind::Goto { target } => vec![*target],
+            if !result[target].contains_idx(l) || !result[target][l] && is_ever_initialized {
-            TerminatorKind::SwitchInt { targets, .. } => targets.all_targets().to_vec(),
+                result[target].insert(l, is_ever_initialized);
+                dfs(db, body, target, l, result);
+            }
+        };
+        match &terminator.kind {
+            TerminatorKind::Goto { target } => process(*target, is_ever_initialized),
+            TerminatorKind::SwitchInt { targets, .. } => {
+                targets.all_targets().iter().for_each(|&it| process(it, is_ever_initialized));
+            }
             TerminatorKind::UnwindResume
             | TerminatorKind::Abort
             | TerminatorKind::Return
-            | TerminatorKind::Unreachable => vec![],
+            | TerminatorKind::Unreachable => (),
             TerminatorKind::Call { target, cleanup, destination, .. } => {
-                if destination.projection.len() == 0 && destination.local == l {
+                if destination.projection.lookup(&body.projection_store).len() == 0
+                    && destination.local == l
+                {
                     is_ever_initialized = true;
                 }
-                target.into_iter().chain(cleanup.into_iter()).copied().collect()
+                target
+                    .into_iter()
+                    .chain(cleanup.into_iter())
+                    .for_each(|&it| process(it, is_ever_initialized));
             }
             TerminatorKind::Drop { target, unwind, place: _ } => {
-                Some(target).into_iter().chain(unwind.into_iter()).copied().collect()
+                iter::once(target)
+                    .into_iter()
+                    .chain(unwind.into_iter())
+                    .for_each(|&it| process(it, is_ever_initialized));
             }
             TerminatorKind::DropAndReplace { .. }
             | TerminatorKind::Assert { .. }
@@ -300,13 +313,7 @@ fn ever_initialized_map(
             | TerminatorKind::FalseEdge { .. }
             | TerminatorKind::FalseUnwind { .. } => {
                 never!("We don't emit these MIR terminators yet");
-                vec![]
+                ()
-            }
-        };
-        for target in targets {
-            if !result[target].contains_idx(l) || !result[target][l] && is_ever_initialized {
-                result[target].insert(l, is_ever_initialized);
-                dfs(db, body, target, l, result);
             }
         }
     }
@@ -315,6 +322,7 @@ fn ever_initialized_map(
         dfs(db, body, body.start_block, l, &mut result);
     }
     for l in body.locals.iter().map(|it| it.0) {
+        db.unwind_if_cancelled();
         if !result[body.start_block].contains_idx(l) {
             result[body.start_block].insert(l, false);
             dfs(db, body, body.start_block, l, &mut result);
@@ -384,7 +392,7 @@ fn mutability_of_locals(
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Yield { .. } => (),
             TerminatorKind::Call { destination, .. } => {
-                if destination.projection.len() == 0 {
+                if destination.projection.lookup(&body.projection_store).len() == 0 {
                     if ever_init_map.get(destination.local).copied().unwrap_or_default() {
                         push_mut_span(destination.local, MirSpan::Unknown);
                     } else {

crates/hir-ty/src/mir/eval.rs

@@ -46,8 +46,8 @@ use crate::{
 
 use super::{
     return_slot, AggregateKind, BasicBlockId, BinOp, CastKind, LocalId, MirBody, MirLowerError,
-    MirSpan, Operand, Place, PlaceElem, ProjectionElem, Rvalue, StatementKind, TerminatorKind,
+    MirSpan, Operand, Place, PlaceElem, ProjectionElem, ProjectionStore, Rvalue, StatementKind,
-    UnOp,
+    TerminatorKind, UnOp,
 };
 
 mod shim;
@@ -215,9 +215,7 @@ impl Interval {
     }
 
     fn write_from_interval(&self, memory: &mut Evaluator<'_>, interval: Interval) -> Result<()> {
-        // FIXME: this could be more efficient
+        memory.copy_from_interval(self.addr, interval)
-        let bytes = &interval.get(memory)?.to_vec();
-        memory.write_memory(self.addr, bytes)
     }
 
     fn slice(self, range: Range<usize>) -> Interval {
@@ -341,7 +339,7 @@ pub enum MirEvalError {
     InvalidVTableId(usize),
     CoerceUnsizedError(Ty),
     LangItemNotFound(LangItem),
-    BrokenLayout(Layout),
+    BrokenLayout(Box<Layout>),
 }
 
 impl MirEvalError {
@@ -410,7 +408,7 @@ impl MirEvalError {
                 err.pretty_print(f, db, span_formatter)?;
             }
             MirEvalError::ConstEvalError(name, err) => {
-                MirLowerError::ConstEvalError(name.clone(), err.clone()).pretty_print(
+                MirLowerError::ConstEvalError((**name).into(), err.clone()).pretty_print(
                     f,
                     db,
                     span_formatter,
@@ -485,17 +483,18 @@ struct DropFlags {
 }
 
 impl DropFlags {
-    fn add_place(&mut self, p: Place) {
+    fn add_place(&mut self, p: Place, store: &ProjectionStore) {
-        if p.iterate_over_parents().any(|it| self.need_drop.contains(&it)) {
+        if p.iterate_over_parents(store).any(|it| self.need_drop.contains(&it)) {
             return;
         }
-        self.need_drop.retain(|it| !p.is_parent(it));
+        self.need_drop.retain(|it| !p.is_parent(it, store));
         self.need_drop.insert(p);
     }
 
-    fn remove_place(&mut self, p: &Place) -> bool {
+    fn remove_place(&mut self, p: &Place, store: &ProjectionStore) -> bool {
         // FIXME: replace parents with parts
-        if let Some(parent) = p.iterate_over_parents().find(|it| self.need_drop.contains(&it)) {
+        if let Some(parent) = p.iterate_over_parents(store).find(|it| self.need_drop.contains(&it))
+        {
             self.need_drop.remove(&parent);
             return true;
         }
@@ -656,7 +655,7 @@ impl Evaluator<'_> {
         let mut addr = locals.ptr[p.local].addr;
         let mut ty: Ty = locals.body.locals[p.local].ty.clone();
         let mut metadata: Option<IntervalOrOwned> = None; // locals are always sized
-        for proj in &*p.projection {
+        for proj in p.projection.lookup(&locals.body.projection_store) {
             let prev_ty = ty.clone();
             ty = self.projected_ty(ty, proj.clone());
             match proj {
@@ -837,7 +836,9 @@ impl Evaluator<'_> {
                                 let addr = self.place_addr(l, &locals)?;
                                 let result = self.eval_rvalue(r, &mut locals)?.to_vec(&self)?;
                                 self.write_memory(addr, &result)?;
-                                locals.drop_flags.add_place(l.clone());
+                                locals
+                                    .drop_flags
+                                    .add_place(l.clone(), &locals.body.projection_store);
                             }
                             StatementKind::Deinit(_) => not_supported!("de-init statement"),
                             StatementKind::StorageLive(_)
@@ -889,7 +890,9 @@ impl Evaluator<'_> {
                                 )?,
                                 it => not_supported!("unknown function type {it:?}"),
                             };
-                            locals.drop_flags.add_place(destination.clone());
+                            locals
+                                .drop_flags
+                                .add_place(destination.clone(), &locals.body.projection_store);
                             if let Some(stack_frame) = stack_frame {
                                 self.code_stack.push(my_stack_frame);
                                 current_block_idx = stack_frame.locals.body.start_block;
@@ -970,7 +973,7 @@ impl Evaluator<'_> {
     ) -> Result<()> {
         let mut remain_args = body.param_locals.len();
         for ((l, interval), value) in locals.ptr.iter().skip(1).zip(args) {
-            locals.drop_flags.add_place(l.into());
+            locals.drop_flags.add_place(l.into(), &locals.body.projection_store);
             match value {
                 IntervalOrOwned::Owned(value) => interval.write_from_bytes(self, &value)?,
                 IntervalOrOwned::Borrowed(value) => interval.write_from_interval(self, value)?,
@@ -1629,7 +1632,7 @@ impl Evaluator<'_> {
         if let Some((offset, size, value)) = tag {
             match result.get_mut(offset..offset + size) {
                 Some(it) => it.copy_from_slice(&value.to_le_bytes()[0..size]),
-                None => return Err(MirEvalError::BrokenLayout(variant_layout.clone())),
+                None => return Err(MirEvalError::BrokenLayout(Box::new(variant_layout.clone()))),
             }
         }
         for (i, op) in values.enumerate() {
@@ -1637,7 +1640,7 @@ impl Evaluator<'_> {
             let op = op.get(&self)?;
             match result.get_mut(offset..offset + op.len()) {
                 Some(it) => it.copy_from_slice(op),
-                None => return Err(MirEvalError::BrokenLayout(variant_layout.clone())),
+                None => return Err(MirEvalError::BrokenLayout(Box::new(variant_layout.clone()))),
             }
         }
         Ok(result)
@@ -1646,7 +1649,7 @@ impl Evaluator<'_> {
     fn eval_operand(&mut self, it: &Operand, locals: &mut Locals) -> Result<Interval> {
         Ok(match it {
             Operand::Copy(p) | Operand::Move(p) => {
-                locals.drop_flags.remove_place(p);
+                locals.drop_flags.remove_place(p, &locals.body.projection_store);
                 self.eval_place(p, locals)?
             }
             Operand::Static(st) => {
@@ -1760,6 +1763,48 @@ impl Evaluator<'_> {
         Ok(())
     }
 
+    fn copy_from_interval(&mut self, addr: Address, r: Interval) -> Result<()> {
+        if r.size == 0 {
+            return Ok(());
+        }
+
+        let oob = || MirEvalError::UndefinedBehavior("out of bounds memory write".to_string());
+
+        match (addr, r.addr) {
+            (Stack(dst), Stack(src)) => {
+                if self.stack.len() < src + r.size || self.stack.len() < dst + r.size {
+                    return Err(oob());
+                }
+                self.stack.copy_within(src..src + r.size, dst)
+            }
+            (Heap(dst), Heap(src)) => {
+                if self.stack.len() < src + r.size || self.stack.len() < dst + r.size {
+                    return Err(oob());
+                }
+                self.heap.copy_within(src..src + r.size, dst)
+            }
+            (Stack(dst), Heap(src)) => {
+                self.stack
+                    .get_mut(dst..dst + r.size)
+                    .ok_or_else(oob)?
+                    .copy_from_slice(self.heap.get(src..src + r.size).ok_or_else(oob)?);
+            }
+            (Heap(dst), Stack(src)) => {
+                self.heap
+                    .get_mut(dst..dst + r.size)
+                    .ok_or_else(oob)?
+                    .copy_from_slice(self.stack.get(src..src + r.size).ok_or_else(oob)?);
+            }
+            _ => {
+                return Err(MirEvalError::UndefinedBehavior(format!(
+                    "invalid memory write at address {addr:?}"
+                )))
+            }
+        }
+
+        Ok(())
+    }
+
     fn size_align_of(&self, ty: &Ty, locals: &Locals) -> Result<Option<(usize, usize)>> {
         if let Some(layout) = self.layout_cache.borrow().get(ty) {
             return Ok(layout
@@ -2468,7 +2513,7 @@ impl Evaluator<'_> {
 
     fn drop_place(&mut self, place: &Place, locals: &mut Locals, span: MirSpan) -> Result<()> {
         let (addr, ty, metadata) = self.place_addr_and_ty_and_metadata(place, locals)?;
-        if !locals.drop_flags.remove_place(place) {
+        if !locals.drop_flags.remove_place(place, &locals.body.projection_store) {
             return Ok(());
         }
         let metadata = match metadata {

crates/hir-ty/src/mir/eval/shim.rs

@@ -4,7 +4,10 @@
 use std::cmp;
 
 use chalk_ir::TyKind;
-use hir_def::resolver::HasResolver;
+use hir_def::{
+    builtin_type::{BuiltinInt, BuiltinUint},
+    resolver::HasResolver,
+};
 use hir_expand::mod_path::ModPath;
 
 use super::*;
@@ -300,21 +303,36 @@ impl Evaluator<'_> {
             BeginPanic => Err(MirEvalError::Panic("<unknown-panic-payload>".to_string())),
             PanicFmt => {
                 let message = (|| {
-                    let resolver = self.db.crate_def_map(self.crate_id).crate_root().resolver(self.db.upcast());
+                    let resolver = self
+                        .db
+                        .crate_def_map(self.crate_id)
+                        .crate_root()
+                        .resolver(self.db.upcast());
                     let Some(format_fn) = resolver.resolve_path_in_value_ns_fully(
                         self.db.upcast(),
-                        &hir_def::path::Path::from_known_path_with_no_generic(ModPath::from_segments(
+                        &hir_def::path::Path::from_known_path_with_no_generic(
-                            hir_expand::mod_path::PathKind::Abs,
+                            ModPath::from_segments(
-                            [name![std], name![fmt], name![format]].into_iter(),
+                                hir_expand::mod_path::PathKind::Abs,
-                        )),
+                                [name![std], name![fmt], name![format]].into_iter(),
+                            ),
+                        ),
                     ) else {
                         not_supported!("std::fmt::format not found");
                     };
-                    let hir_def::resolver::ValueNs::FunctionId(format_fn) = format_fn else { not_supported!("std::fmt::format is not a function") };
+                    let hir_def::resolver::ValueNs::FunctionId(format_fn) = format_fn else {
-                    let message_string = self.interpret_mir(self.db.mir_body(format_fn.into()).map_err(|e| MirEvalError::MirLowerError(format_fn, e))?, args.map(|x| IntervalOrOwned::Owned(x.clone())))?;
+                        not_supported!("std::fmt::format is not a function")
-                    let addr = Address::from_bytes(&message_string[self.ptr_size()..2 * self.ptr_size()])?;
+                    };
+                    let message_string = self.interpret_mir(
+                        self.db
+                            .mir_body(format_fn.into())
+                            .map_err(|e| MirEvalError::MirLowerError(format_fn, e))?,
+                        args.map(|x| IntervalOrOwned::Owned(x.clone())),
+                    )?;
+                    let addr =
+                        Address::from_bytes(&message_string[self.ptr_size()..2 * self.ptr_size()])?;
                     let size = from_bytes!(usize, message_string[2 * self.ptr_size()..]);
-                    Ok(std::string::String::from_utf8_lossy(self.read_memory(addr, size)?).into_owned())
+                    Ok(std::string::String::from_utf8_lossy(self.read_memory(addr, size)?)
+                        .into_owned())
                 })()
                 .unwrap_or_else(|e| format!("Failed to render panic format args: {e:?}"));
                 Err(MirEvalError::Panic(message))
@@ -483,9 +501,7 @@ impl Evaluator<'_> {
             }
             "syscall" => {
                 let Some((id, rest)) = args.split_first() else {
-                    return Err(MirEvalError::TypeError(
+                    return Err(MirEvalError::TypeError("syscall arg1 is not provided"));
-                        "syscall arg1 is not provided",
-                    ));
                 };
                 let id = from_bytes!(i64, id.get(self)?);
                 self.exec_syscall(id, rest, destination, locals, span)
@@ -710,7 +726,8 @@ impl Evaluator<'_> {
         }
         match name {
             "size_of" => {
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
                 else {
                     return Err(MirEvalError::TypeError("size_of generic arg is not provided"));
                 };
@@ -718,14 +735,17 @@ impl Evaluator<'_> {
                 destination.write_from_bytes(self, &size.to_le_bytes()[0..destination.size])
             }
             "min_align_of" | "pref_align_of" => {
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner)) else {
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                else {
                     return Err(MirEvalError::TypeError("align_of generic arg is not provided"));
                 };
                 let align = self.layout(ty)?.align.abi.bytes();
                 destination.write_from_bytes(self, &align.to_le_bytes()[0..destination.size])
             }
             "size_of_val" => {
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
                 else {
                     return Err(MirEvalError::TypeError("size_of_val generic arg is not provided"));
                 };
@@ -741,8 +761,12 @@ impl Evaluator<'_> {
                 }
             }
             "min_align_of_val" => {
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner)) else {
+                let Some(ty) =
-                    return Err(MirEvalError::TypeError("min_align_of_val generic arg is not provided"));
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                else {
+                    return Err(MirEvalError::TypeError(
+                        "min_align_of_val generic arg is not provided",
+                    ));
                 };
                 let [arg] = args else {
                     return Err(MirEvalError::TypeError("min_align_of_val args are not provided"));
@@ -756,7 +780,8 @@ impl Evaluator<'_> {
                 }
             }
             "type_name" => {
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
                 else {
                     return Err(MirEvalError::TypeError("type_name generic arg is not provided"));
                 };
@@ -779,7 +804,8 @@ impl Evaluator<'_> {
                     .write_from_bytes(self, &len.to_le_bytes())
             }
             "needs_drop" => {
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
                 else {
                     return Err(MirEvalError::TypeError("size_of generic arg is not provided"));
                 };
@@ -831,9 +857,12 @@ impl Evaluator<'_> {
                 let lhs = i128::from_le_bytes(pad16(lhs.get(self)?, false));
                 let rhs = i128::from_le_bytes(pad16(rhs.get(self)?, false));
                 let ans = lhs.wrapping_sub(rhs);
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
                 else {
-                    return Err(MirEvalError::TypeError("ptr_offset_from generic arg is not provided"));
+                    return Err(MirEvalError::TypeError(
+                        "ptr_offset_from generic arg is not provided",
+                    ));
                 };
                 let size = self.size_of_sized(ty, locals, "ptr_offset_from arg")? as i128;
                 let ans = ans / size;
@@ -940,7 +969,8 @@ impl Evaluator<'_> {
                         "copy_nonoverlapping args are not provided",
                     ));
                 };
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
                 else {
                     return Err(MirEvalError::TypeError(
                         "copy_nonoverlapping generic arg is not provided",
@@ -959,9 +989,45 @@ impl Evaluator<'_> {
                 let [ptr, offset] = args else {
                     return Err(MirEvalError::TypeError("offset args are not provided"));
                 };
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let ty = if name == "offset" {
-                else {
+                    let Some(ty0) =
-                    return Err(MirEvalError::TypeError("offset generic arg is not provided"));
+                        generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                    else {
+                        return Err(MirEvalError::TypeError("offset generic arg is not provided"));
+                    };
+                    let Some(ty1) =
+                        generic_args.as_slice(Interner).get(1).and_then(|it| it.ty(Interner))
+                    else {
+                        return Err(MirEvalError::TypeError("offset generic arg is not provided"));
+                    };
+                    if !matches!(
+                        ty1.as_builtin(),
+                        Some(
+                            BuiltinType::Int(BuiltinInt::Isize)
+                                | BuiltinType::Uint(BuiltinUint::Usize)
+                        )
+                    ) {
+                        return Err(MirEvalError::TypeError(
+                            "offset generic arg is not usize or isize",
+                        ));
+                    }
+                    match ty0.as_raw_ptr() {
+                        Some((ty, _)) => ty,
+                        None => {
+                            return Err(MirEvalError::TypeError(
+                                "offset generic arg is not a raw pointer",
+                            ));
+                        }
+                    }
+                } else {
+                    let Some(ty) =
+                        generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                    else {
+                        return Err(MirEvalError::TypeError(
+                            "arith_offset generic arg is not provided",
+                        ));
+                    };
+                    ty
                 };
                 let ptr = u128::from_le_bytes(pad16(ptr.get(self)?, false));
                 let offset = u128::from_le_bytes(pad16(offset.get(self)?, false));
@@ -1079,7 +1145,8 @@ impl Evaluator<'_> {
                 let [arg] = args else {
                     return Err(MirEvalError::TypeError("discriminant_value arg is not provided"));
                 };
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
                 else {
                     return Err(MirEvalError::TypeError(
                         "discriminant_value generic arg is not provided",
@@ -1133,17 +1200,32 @@ impl Evaluator<'_> {
                 let addr = Address::from_bytes(arg.interval.get(self)?)?;
                 destination.write_from_interval(self, Interval { addr, size: destination.size })
             }
+            "write_via_move" => {
+                let [ptr, val] = args else {
+                    return Err(MirEvalError::TypeError("write_via_move args are not provided"));
+                };
+                let dst = Address::from_bytes(ptr.get(self)?)?;
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                else {
+                    return Err(MirEvalError::TypeError(
+                        "write_via_copy generic arg is not provided",
+                    ));
+                };
+                let size = self.size_of_sized(ty, locals, "write_via_move ptr type")?;
+                Interval { addr: dst, size }.write_from_interval(self, val.interval)?;
+                Ok(())
+            }
             "write_bytes" => {
                 let [dst, val, count] = args else {
                     return Err(MirEvalError::TypeError("write_bytes args are not provided"));
                 };
                 let count = from_bytes!(usize, count.get(self)?);
                 let val = from_bytes!(u8, val.get(self)?);
-                let Some(ty) = generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                let Some(ty) =
+                    generic_args.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
                 else {
-                    return Err(MirEvalError::TypeError(
+                    return Err(MirEvalError::TypeError("write_bytes generic arg is not provided"));
-                        "write_bytes generic arg is not provided",
-                    ));
                 };
                 let dst = Address::from_bytes(dst.get(self)?)?;
                 let size = self.size_of_sized(ty, locals, "copy_nonoverlapping ptr type")?;

crates/hir-ty/src/mir/eval/shim/simd.rs

@@ -45,7 +45,9 @@ impl Evaluator<'_> {
                 };
                 match try_const_usize(self.db, len) {
                     Some(len) => {
-                        let Some(ty) = subst.as_slice(Interner).get(0).and_then(|it| it.ty(Interner)) else {
+                        let Some(ty) =
+                            subst.as_slice(Interner).get(0).and_then(|it| it.ty(Interner))
+                        else {
                             return Err(MirEvalError::TypeError("simd type with no ty param"));
                         };
                         Ok((len as usize, ty.clone()))

crates/hir-ty/src/mir/lower.rs

@@ -71,7 +71,7 @@ struct MirLowerCtx<'a> {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum MirLowerError {
-    ConstEvalError(String, Box<ConstEvalError>),
+    ConstEvalError(Box<str>, Box<ConstEvalError>),
     LayoutError(LayoutError),
     IncompleteExpr,
     IncompletePattern,
@@ -84,7 +84,7 @@ pub enum MirLowerError {
     UnsizedTemporary(Ty),
     MissingFunctionDefinition(DefWithBodyId, ExprId),
     TypeMismatch(TypeMismatch),
-    /// This should be never happen. Type mismatch should catch everything.
+    /// This should never happen. Type mismatch should catch everything.
     TypeError(&'static str),
     NotSupported(String),
     ContinueWithoutLoop,
@@ -244,6 +244,7 @@ impl<'ctx> MirLowerCtx<'ctx> {
         let locals = Arena::new();
         let binding_locals: ArenaMap<BindingId, LocalId> = ArenaMap::new();
         let mir = MirBody {
+            projection_store: ProjectionStore::default(),
             basic_blocks,
             locals,
             start_block,
@@ -370,6 +371,12 @@ impl<'ctx> MirLowerCtx<'ctx> {
         mut current: BasicBlockId,
     ) -> Result<Option<BasicBlockId>> {
         match &self.body.exprs[expr_id] {
+            Expr::OffsetOf(_) => {
+                not_supported!("builtin#offset_of")
+            }
+            Expr::InlineAsm(_) => {
+                not_supported!("builtin#asm")
+            }
             Expr::Missing => {
                 if let DefWithBodyId::FunctionId(f) = self.owner {
                     let assoc = f.lookup(self.db.upcast());
@@ -803,36 +810,34 @@ impl<'ctx> MirLowerCtx<'ctx> {
                             current = c;
                             operands[u32::from(field_id.into_raw()) as usize] = Some(op);
                         }
-                        self.push_assignment(
+                        let rvalue = Rvalue::Aggregate(
-                            current,
+                            AggregateKind::Adt(variant_id, subst),
-                            place,
+                            match spread_place {
-                            Rvalue::Aggregate(
+                                Some(sp) => operands
-                                AggregateKind::Adt(variant_id, subst),
+                                    .into_iter()
-                                match spread_place {
+                                    .enumerate()
-                                    Some(sp) => operands
+                                    .map(|(i, it)| match it {
-                                        .into_iter()
+                                        Some(it) => it,
-                                        .enumerate()
+                                        None => {
-                                        .map(|(i, it)| match it {
+                                            let p = sp.project(
-                                            Some(it) => it,
+                                                ProjectionElem::Field(FieldId {
-                                            None => {
+                                                    parent: variant_id,
-                                                let p =
+                                                    local_id: LocalFieldId::from_raw(RawIdx::from(
-                                                    sp.project(ProjectionElem::Field(FieldId {
+                                                        i as u32,
-                                                        parent: variant_id,
+                                                    )),
-                                                        local_id: LocalFieldId::from_raw(
+                                                }),
-                                                            RawIdx::from(i as u32),
+                                                &mut self.result.projection_store,
-                                                        ),
+                                            );
-                                                    }));
+                                            Operand::Copy(p)
-                                                Operand::Copy(p)
+                                        }
-                                            }
+                                    })
-                                        })
+                                    .collect(),
-                                        .collect(),
+                                None => operands.into_iter().collect::<Option<_>>().ok_or(
-                                    None => operands.into_iter().collect::<Option<_>>().ok_or(
+                                    MirLowerError::TypeError("missing field in record literal"),
-                                        MirLowerError::TypeError("missing field in record literal"),
+                                )?,
-                                    )?,
+                            },
-                                },
-                            ),
-                            expr_id.into(),
                         );
+                        self.push_assignment(current, place, rvalue, expr_id.into());
                         Ok(Some(current))
                     }
                     VariantId::UnionId(union_id) => {
@@ -841,10 +846,10 @@ impl<'ctx> MirLowerCtx<'ctx> {
                         };
                         let local_id =
                             variant_data.field(name).ok_or(MirLowerError::UnresolvedField)?;
-                        let place = place.project(PlaceElem::Field(FieldId {
+                        let place = place.project(
-                            parent: union_id.into(),
+                            PlaceElem::Field(FieldId { parent: union_id.into(), local_id }),
-                            local_id,
+                            &mut self.result.projection_store,
-                        }));
+                        );
                         self.lower_expr_to_place(*expr, place, current)
                     }
                 }
@@ -898,7 +903,7 @@ impl<'ctx> MirLowerCtx<'ctx> {
                 else {
                     return Ok(None);
                 };
-                let p = place.project(ProjectionElem::Deref);
+                let p = place.project(ProjectionElem::Deref, &mut self.result.projection_store);
                 self.push_assignment(current, p, operand.into(), expr_id.into());
                 Ok(Some(current))
             }
@@ -1120,27 +1125,31 @@ impl<'ctx> MirLowerCtx<'ctx> {
                 for capture in captures.iter() {
                     let p = Place {
                         local: self.binding_local(capture.place.local)?,
-                        projection: capture
+                        projection: self.result.projection_store.intern(
-                            .place
+                            capture
-                            .projections
+                                .place
-                            .clone()
+                                .projections
-                            .into_iter()
+                                .clone()
-                            .map(|it| match it {
+                                .into_iter()
-                                ProjectionElem::Deref => ProjectionElem::Deref,
+                                .map(|it| match it {
-                                ProjectionElem::Field(it) => ProjectionElem::Field(it),
+                                    ProjectionElem::Deref => ProjectionElem::Deref,
-                                ProjectionElem::TupleOrClosureField(it) => {
+                                    ProjectionElem::Field(it) => ProjectionElem::Field(it),
-                                    ProjectionElem::TupleOrClosureField(it)
+                                    ProjectionElem::TupleOrClosureField(it) => {
-                                }
+                                        ProjectionElem::TupleOrClosureField(it)
-                                ProjectionElem::ConstantIndex { offset, from_end } => {
+                                    }
-                                    ProjectionElem::ConstantIndex { offset, from_end }
+                                    ProjectionElem::ConstantIndex { offset, from_end } => {
-                                }
+                                        ProjectionElem::ConstantIndex { offset, from_end }
-                                ProjectionElem::Subslice { from, to } => {
+                                    }
-                                    ProjectionElem::Subslice { from, to }
+                                    ProjectionElem::Subslice { from, to } => {
-                                }
+                                        ProjectionElem::Subslice { from, to }
-                                ProjectionElem::OpaqueCast(it) => ProjectionElem::OpaqueCast(it),
+                                    }
-                                ProjectionElem::Index(it) => match it {},
+                                    ProjectionElem::OpaqueCast(it) => {
-                            })
+                                        ProjectionElem::OpaqueCast(it)
-                            .collect(),
+                                    }
+                                    ProjectionElem::Index(it) => match it {},
+                                })
+                                .collect(),
+                        ),
                     };
                     match &capture.kind {
                         CaptureKind::ByRef(bk) => {
@@ -1201,7 +1210,8 @@ impl<'ctx> MirLowerCtx<'ctx> {
                     let Some(values) = elements
                         .iter()
                         .map(|it| {
-                            let Some((o, c)) = self.lower_expr_to_some_operand(*it, current)? else {
+                            let Some((o, c)) = self.lower_expr_to_some_operand(*it, current)?
+                            else {
                                 return Ok(None);
                             };
                             current = c;
@@ -1254,12 +1264,12 @@ impl<'ctx> MirLowerCtx<'ctx> {
         match &self.body.exprs[lhs] {
             Expr::Tuple { exprs, is_assignee_expr: _ } => {
                 for (i, expr) in exprs.iter().enumerate() {
-                    let Some(c) = self.lower_destructing_assignment(
+                    let rhs = rhs.project(
-                        current,
+                        ProjectionElem::TupleOrClosureField(i),
-                        *expr,
+                        &mut self.result.projection_store,
-                        rhs.project(ProjectionElem::TupleOrClosureField(i)),
+                    );
-                        span,
+                    let Some(c) = self.lower_destructing_assignment(current, *expr, rhs, span)?
-                    )? else {
+                    else {
                         return Ok(None);
                     };
                     current = c;
@@ -1268,8 +1278,7 @@ impl<'ctx> MirLowerCtx<'ctx> {
             }
             Expr::Underscore => Ok(Some(current)),
             _ => {
-                let Some((lhs_place, current)) =
+                let Some((lhs_place, current)) = self.lower_expr_as_place(current, lhs, false)?
-                    self.lower_expr_as_place(current, lhs, false)?
                 else {
                     return Ok(None);
                 };
@@ -1286,9 +1295,7 @@ impl<'ctx> MirLowerCtx<'ctx> {
         rhs: ExprId,
         span: MirSpan,
     ) -> Result<Option<BasicBlockId>> {
-        let Some((rhs_op, current)) =
+        let Some((rhs_op, current)) = self.lower_expr_to_some_operand(rhs, current)? else {
-            self.lower_expr_to_some_operand(rhs, current)?
-        else {
             return Ok(None);
         };
         if matches!(&self.body.exprs[lhs], Expr::Underscore) {
@@ -1303,9 +1310,7 @@ impl<'ctx> MirLowerCtx<'ctx> {
             self.push_assignment(current, temp.clone(), rhs_op.into(), span);
             return self.lower_destructing_assignment(current, lhs, temp, span);
         }
-        let Some((lhs_place, current)) =
+        let Some((lhs_place, current)) = self.lower_expr_as_place(current, lhs, false)? else {
-            self.lower_expr_as_place(current, lhs, false)?
-        else {
             return Ok(None);
         };
         self.push_assignment(current, lhs_place, rhs_op.into(), span);
@@ -1320,17 +1325,21 @@ impl<'ctx> MirLowerCtx<'ctx> {
         placeholder_subst
     }
 
-    fn push_field_projection(&self, place: &mut Place, expr_id: ExprId) -> Result<()> {
+    fn push_field_projection(&mut self, place: &mut Place, expr_id: ExprId) -> Result<()> {
         if let Expr::Field { expr, name } = &self.body[expr_id] {
             if let TyKind::Tuple(..) = self.expr_ty_after_adjustments(*expr).kind(Interner) {
                 let index = name
                     .as_tuple_index()
                     .ok_or(MirLowerError::TypeError("named field on tuple"))?;
-                *place = place.project(ProjectionElem::TupleOrClosureField(index))
+                *place = place.project(
+                    ProjectionElem::TupleOrClosureField(index),
+                    &mut self.result.projection_store,
+                )
             } else {
                 let field =
                     self.infer.field_resolution(expr_id).ok_or(MirLowerError::UnresolvedField)?;
-                *place = place.project(ProjectionElem::Field(field));
+                *place =
+                    place.project(ProjectionElem::Field(field), &mut self.result.projection_store);
             }
         } else {
             not_supported!("")
@@ -1447,7 +1456,7 @@ impl<'ctx> MirLowerCtx<'ctx> {
             let name = const_id.name(self.db.upcast());
             self.db
                 .const_eval(const_id.into(), subst, None)
-                .map_err(|e| MirLowerError::ConstEvalError(name, Box::new(e)))?
+                .map_err(|e| MirLowerError::ConstEvalError(name.into(), Box::new(e)))?
         };
         Ok(Operand::Constant(c))
     }
@@ -1844,7 +1853,7 @@ impl<'ctx> MirLowerCtx<'ctx> {
                     data.name.display(self.db.upcast()),
                     data.variants[variant.local_id].name.display(self.db.upcast())
                 );
-                Err(MirLowerError::ConstEvalError(name, Box::new(e)))
+                Err(MirLowerError::ConstEvalError(name.into(), Box::new(e)))
             }
         }
     }
@@ -1992,13 +2001,14 @@ pub fn mir_body_for_closure_query(
         FnTrait::FnOnce => vec![],
         FnTrait::FnMut | FnTrait::Fn => vec![ProjectionElem::Deref],
     };
-    ctx.result.walk_places(|p| {
+    ctx.result.walk_places(|p, store| {
         if let Some(it) = upvar_map.get(&p.local) {
             let r = it.iter().find(|it| {
-                if p.projection.len() < it.0.place.projections.len() {
+                if p.projection.lookup(&store).len() < it.0.place.projections.len() {
                     return false;
                 }
-                for (it, y) in p.projection.iter().zip(it.0.place.projections.iter()) {
+                for (it, y) in p.projection.lookup(&store).iter().zip(it.0.place.projections.iter())
+                {
                     match (it, y) {
                         (ProjectionElem::Deref, ProjectionElem::Deref) => (),
                         (ProjectionElem::Field(it), ProjectionElem::Field(y)) if it == y => (),
@@ -2016,13 +2026,18 @@ pub fn mir_body_for_closure_query(
                     p.local = closure_local;
                     let mut next_projs = closure_projection.clone();
                     next_projs.push(PlaceElem::TupleOrClosureField(it.1));
-                    let prev_projs = mem::take(&mut p.projection);
+                    let prev_projs = p.projection;
                     if it.0.kind != CaptureKind::ByValue {
                         next_projs.push(ProjectionElem::Deref);
                     }
-                    next_projs
+                    next_projs.extend(
-                        .extend(prev_projs.iter().cloned().skip(it.0.place.projections.len()));
+                        prev_projs
-                    p.projection = next_projs.into();
+                            .lookup(&store)
+                            .iter()
+                            .cloned()
+                            .skip(it.0.place.projections.len()),
+                    );
+                    p.projection = store.intern(next_projs.into());
                 }
                 None => err = Some(p.clone()),
             }

crates/hir-ty/src/mir/lower/as_place.rs

@@ -70,7 +70,7 @@ impl MirLowerCtx<'_> {
                     else {
                         return Ok(None);
                     };
-                    it.0 = it.0.project(ProjectionElem::Deref);
+                    it.0 = it.0.project(ProjectionElem::Deref, &mut self.result.projection_store);
                     Ok(Some(it))
                 }
                 Adjust::Deref(Some(od)) => {
@@ -152,7 +152,10 @@ impl MirLowerCtx<'_> {
                             Operand::Static(s).into(),
                             expr_id.into(),
                         );
-                        Ok(Some((temp.project(ProjectionElem::Deref), current)))
+                        Ok(Some((
+                            temp.project(ProjectionElem::Deref, &mut self.result.projection_store),
+                            current,
+                        )))
                     }
                     _ => try_rvalue(self),
                 }
@@ -203,7 +206,7 @@ impl MirLowerCtx<'_> {
                     else {
                         return Ok(None);
                     };
-                    r = r.project(ProjectionElem::Deref);
+                    r = r.project(ProjectionElem::Deref, &mut self.result.projection_store);
                     Ok(Some((r, current)))
                 }
                 _ => try_rvalue(self),
@@ -267,7 +270,8 @@ impl MirLowerCtx<'_> {
                 else {
                     return Ok(None);
                 };
-                p_base = p_base.project(ProjectionElem::Index(l_index));
+                p_base = p_base
+                    .project(ProjectionElem::Index(l_index), &mut self.result.projection_store);
                 Ok(Some((p_base, current)))
             }
             _ => try_rvalue(self),
@@ -308,7 +312,7 @@ impl MirLowerCtx<'_> {
         else {
             return Ok(None);
         };
-        result = result.project(ProjectionElem::Deref);
+        result = result.project(ProjectionElem::Deref, &mut self.result.projection_store);
         Ok(Some((result, current)))
     }
 
@@ -363,7 +367,7 @@ impl MirLowerCtx<'_> {
         else {
             return Ok(None);
         };
-        result = result.project(ProjectionElem::Deref);
+        result = result.project(ProjectionElem::Deref, &mut self.result.projection_store);
         Ok(Some((result, current)))
     }
 }

crates/hir-ty/src/mir/lower/pattern_matching.rs

@@ -81,13 +81,16 @@ impl MirLowerCtx<'_> {
         mode: MatchingMode,
     ) -> Result<(BasicBlockId, Option<BasicBlockId>)> {
         let cnt = self.infer.pat_adjustments.get(&pattern).map(|x| x.len()).unwrap_or_default();
-        cond_place.projection = cond_place
+        cond_place.projection = self.result.projection_store.intern(
-            .projection
+            cond_place
-            .iter()
+                .projection
-            .cloned()
+                .lookup(&self.result.projection_store)
-            .chain((0..cnt).map(|_| ProjectionElem::Deref))
+                .iter()
-            .collect::<Vec<_>>()
+                .cloned()
-            .into();
+                .chain((0..cnt).map(|_| ProjectionElem::Deref))
+                .collect::<Vec<_>>()
+                .into(),
+        );
         Ok(match &self.body.pats[pattern] {
             Pat::Missing => return Err(MirLowerError::IncompletePattern),
             Pat::Wild => (current, current_else),
@@ -262,20 +265,23 @@ impl MirLowerCtx<'_> {
                     }
                 }
                 for (i, &pat) in prefix.iter().enumerate() {
-                    let next_place = (&mut cond_place).project(ProjectionElem::ConstantIndex {
+                    let next_place = (&mut cond_place).project(
-                        offset: i as u64,
+                        ProjectionElem::ConstantIndex { offset: i as u64, from_end: false },
-                        from_end: false,
+                        &mut self.result.projection_store,
-                    });
+                    );
                     (current, current_else) =
                         self.pattern_match_inner(current, current_else, next_place, pat, mode)?;
                 }
                 if let Some(slice) = slice {
                     if mode == MatchingMode::Bind {
                         if let Pat::Bind { id, subpat: _ } = self.body[*slice] {
-                            let next_place = (&mut cond_place).project(ProjectionElem::Subslice {
+                            let next_place = (&mut cond_place).project(
-                                from: prefix.len() as u64,
+                                ProjectionElem::Subslice {
-                                to: suffix.len() as u64,
+                                    from: prefix.len() as u64,
-                            });
+                                    to: suffix.len() as u64,
+                                },
+                                &mut self.result.projection_store,
+                            );
                             (current, current_else) = self.pattern_match_binding(
                                 id,
                                 next_place,
@@ -287,10 +293,10 @@ impl MirLowerCtx<'_> {
                     }
                 }
                 for (i, &pat) in suffix.iter().enumerate() {
-                    let next_place = (&mut cond_place).project(ProjectionElem::ConstantIndex {
+                    let next_place = (&mut cond_place).project(
-                        offset: i as u64,
+                        ProjectionElem::ConstantIndex { offset: i as u64, from_end: true },
-                        from_end: true,
+                        &mut self.result.projection_store,
-                    });
+                    );
                     (current, current_else) =
                         self.pattern_match_inner(current, current_else, next_place, pat, mode)?;
                 }
@@ -412,13 +418,11 @@ impl MirLowerCtx<'_> {
                     mode,
                 )?
             }
-            Pat::Ref { pat, mutability: _ } => self.pattern_match_inner(
+            Pat::Ref { pat, mutability: _ } => {
-                current,
+                let cond_place =
-                current_else,
+                    cond_place.project(ProjectionElem::Deref, &mut self.result.projection_store);
-                cond_place.project(ProjectionElem::Deref),
+                self.pattern_match_inner(current, current_else, cond_place, *pat, mode)?
-                *pat,
+            }
-                mode,
-            )?,
             Pat::Box { .. } => not_supported!("box pattern"),
             Pat::ConstBlock(_) => not_supported!("const block pattern"),
         })
@@ -594,7 +598,7 @@ impl MirLowerCtx<'_> {
         mode: MatchingMode,
     ) -> Result<(BasicBlockId, Option<BasicBlockId>)> {
         for (proj, arg) in args {
-            let cond_place = cond_place.project(proj);
+            let cond_place = cond_place.project(proj, &mut self.result.projection_store);
             (current, current_else) =
                 self.pattern_match_inner(current, current_else, cond_place, arg, mode)?;
         }

crates/hir-ty/src/mir/pretty.rs

@@ -329,7 +329,7 @@ impl<'a> MirPrettyCtx<'a> {
                 }
             }
         }
-        f(self, p.local, &p.projection);
+        f(self, p.local, &p.projection.lookup(&self.body.projection_store));
     }
 
     fn operand(&mut self, r: &Operand) {

crates/hir-ty/src/tests/simple.rs

@@ -2,55 +2,6 @@ use expect_test::expect;
 
 use super::{check, check_infer, check_no_mismatches, check_types};
 
-#[test]
-fn infer_box() {
-    check_types(
-        r#"
-//- /main.rs crate:main deps:std
-fn test() {
-    let x = box 1;
-    let t = (x, box x, box &1, box [1]);
-    t;
-} //^ (Box<i32>, Box<Box<i32>>, Box<&i32>, Box<[i32; 1]>)
-
-//- /std.rs crate:std
-#[prelude_import] use prelude::*;
-mod prelude {}
-
-mod boxed {
-    #[lang = "owned_box"]
-    pub struct Box<T: ?Sized> {
-        inner: *mut T,
-    }
-}
-"#,
-    );
-}
-
-#[test]
-fn infer_box_with_allocator() {
-    check_types(
-        r#"
-//- /main.rs crate:main deps:std
-fn test() {
-    let x = box 1;
-    let t = (x, box x, box &1, box [1]);
-    t;
-} //^ (Box<i32, {unknown}>, Box<Box<i32, {unknown}>, {unknown}>, Box<&i32, {unknown}>, Box<[i32; 1], {unknown}>)
-
-//- /std.rs crate:std
-#[prelude_import] use prelude::*;
-mod boxed {
-    #[lang = "owned_box"]
-    pub struct Box<T: ?Sized, A: Allocator> {
-        inner: *mut T,
-        allocator: A,
-    }
-}
-"#,
-    );
-}
-
 #[test]
 fn infer_adt_self() {
     check_types(
@@ -2763,8 +2714,8 @@ impl<T> [T] {
 }
 
 fn test() {
-    let vec = <[_]>::into_vec(box [1i32]);
+    let vec = <[_]>::into_vec(#[rustc_box] Box::new([1i32]));
-    let v: Vec<Box<dyn B>> = <[_]> :: into_vec(box [box Astruct]);
+    let v: Vec<Box<dyn B>> = <[_]> :: into_vec(#[rustc_box] Box::new([#[rustc_box] Box::new(Astruct)]));
 }
 
 trait B{}
@@ -2774,20 +2725,20 @@ impl B for Astruct {}
         expect![[r#"
             604..608 'self': Box<[T], A>
             637..669 '{     ...     }': Vec<T, A>
-            683..796 '{     ...t]); }': ()
+            683..853 '{     ...])); }': ()
             693..696 'vec': Vec<i32, Global>
             699..714 '<[_]>::into_vec': fn into_vec<i32, Global>(Box<[i32], Global>) -> Vec<i32, Global>
-            699..726 '<[_]>:...1i32])': Vec<i32, Global>
+            699..745 '<[_]>:...i32]))': Vec<i32, Global>
-            715..725 'box [1i32]': Box<[i32; 1], Global>
+            715..744 '#[rust...1i32])': Box<[i32; 1], Global>
-            719..725 '[1i32]': [i32; 1]
+            737..743 '[1i32]': [i32; 1]
-            720..724 '1i32': i32
+            738..742 '1i32': i32
-            736..737 'v': Vec<Box<dyn B, Global>, Global>
+            755..756 'v': Vec<Box<dyn B, Global>, Global>
-            757..774 '<[_]> ...to_vec': fn into_vec<Box<dyn B, Global>, Global>(Box<[Box<dyn B, Global>], Global>) -> Vec<Box<dyn B, Global>, Global>
+            776..793 '<[_]> ...to_vec': fn into_vec<Box<dyn B, Global>, Global>(Box<[Box<dyn B, Global>], Global>) -> Vec<Box<dyn B, Global>, Global>
-            757..793 '<[_]> ...ruct])': Vec<Box<dyn B, Global>, Global>
+            776..850 '<[_]> ...ct)]))': Vec<Box<dyn B, Global>, Global>
-            775..792 'box [b...truct]': Box<[Box<dyn B, Global>; 1], Global>
+            794..849 '#[rust...uct)])': Box<[Box<dyn B, Global>; 1], Global>
-            779..792 '[box Astruct]': [Box<dyn B, Global>; 1]
+            816..848 '[#[rus...ruct)]': [Box<dyn B, Global>; 1]
-            780..791 'box Astruct': Box<Astruct, Global>
+            817..847 '#[rust...truct)': Box<Astruct, Global>
-            784..791 'Astruct': Astruct
+            839..846 'Astruct': Astruct
         "#]],
     )
 }
@@ -3649,3 +3600,30 @@ fn main() {
 "#,
     );
 }
+
+#[test]
+fn offset_of() {
+    check_types(
+        r#"
+fn main() {
+    builtin#offset_of((,), 0);
+ // ^^^^^^^^^^^^^^^^^^^^^^^^^ usize
+}
+"#,
+    );
+}
+
+#[test]
+fn builtin_format_args() {
+    check(
+        r#"
+//- minicore: fmt
+fn main() {
+    let are = "are";
+    let count = 10;
+    builtin#format_args("hello {count:02} {} friends, we {are:?} {0}{last}", "fancy", last = "!");
+ // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type: Arguments<'_>
+}
+"#,
+    );
+}

crates/hir-ty/src/tests/traits.rs

@@ -162,16 +162,16 @@ unsafe impl Allocator for Global {}
 
 #[lang = "owned_box"]
 #[fundamental]
-pub struct Box<T: ?Sized, A: Allocator = Global>;
+pub struct Box<T: ?Sized, A: Allocator = Global>(T);
 
 impl<T: ?Sized + Unsize<U>, U: ?Sized, A: Allocator> CoerceUnsized<Box<U, A>> for Box<T, A> {}
 
 fn send() ->  Box<dyn Future<Output = ()> + Send + 'static>{
-    box async move {}
+    Box(async move {})
 }
 
 fn not_send() -> Box<dyn Future<Output = ()> + 'static> {
-    box async move {}
+    Box(async move {})
 }
     "#,
     );
@@ -3057,7 +3057,7 @@ impl<T: ?Sized> core::ops::Deref for Box<T> {
 
 fn foo() {
     let s = None;
-    let f: Box<dyn FnOnce(&Option<i32>)> = box (|ps| {});
+    let f: Box<dyn FnOnce(&Option<i32>)> = Box { inner: &mut (|ps| {}) };
     f(&s);
 }"#,
         expect![[r#"
@@ -3068,19 +3068,19 @@ fn foo() {
             186..197 '*self.inner': T
             187..191 'self': &Box<T>
             187..197 'self.inner': *mut T
-            218..308 '{     ...&s); }': ()
+            218..324 '{     ...&s); }': ()
             228..229 's': Option<i32>
             232..236 'None': Option<i32>
             246..247 'f': Box<dyn FnOnce(&Option<i32>)>
-            281..294 'box (|ps| {})': Box<impl Fn(&Option<i32>)>
+            281..310 'Box { ... {}) }': Box<dyn FnOnce(&Option<i32>)>
-            286..293 '|ps| {}': impl Fn(&Option<i32>)
+            294..308 '&mut (|ps| {})': &mut impl Fn(&Option<i32>)
-            287..289 'ps': &Option<i32>
+            300..307 '|ps| {}': impl Fn(&Option<i32>)
-            291..293 '{}': ()
+            301..303 'ps': &Option<i32>
-            300..301 'f': Box<dyn FnOnce(&Option<i32>)>
+            305..307 '{}': ()
-            300..305 'f(&s)': ()
+            316..317 'f': Box<dyn FnOnce(&Option<i32>)>
-            302..304 '&s': &Option<i32>
+            316..321 'f(&s)': ()
-            303..304 's': Option<i32>
+            318..320 '&s': &Option<i32>
-            281..294: expected Box<dyn FnOnce(&Option<i32>)>, got Box<impl Fn(&Option<i32>)>
+            319..320 's': Option<i32>
         "#]],
     );
 }

crates/hir/src/attrs.rs

@@ -1,39 +1,27 @@
 //! Attributes & documentation for hir types.
 
 use hir_def::{
-    attr::{AttrsWithOwner, Documentation},
+    attr::AttrsWithOwner,
     item_scope::ItemInNs,
     path::{ModPath, Path},
     per_ns::Namespace,
     resolver::{HasResolver, Resolver, TypeNs},
-    AssocItemId, AttrDefId, GenericParamId, ModuleDefId,
+    AssocItemId, AttrDefId, ModuleDefId,
 };
 use hir_expand::{hygiene::Hygiene, name::Name};
 use hir_ty::db::HirDatabase;
 use syntax::{ast, AstNode};
 
 use crate::{
-    Adt, AsAssocItem, AssocItem, BuiltinType, Const, ConstParam, Enum, ExternCrateDecl, Field,
+    Adt, AsAssocItem, AssocItem, BuiltinType, Const, ConstParam, DocLinkDef, Enum, ExternCrateDecl,
-    Function, GenericParam, Impl, LifetimeParam, Macro, Module, ModuleDef, Static, Struct, Trait,
+    Field, Function, GenericParam, Impl, LifetimeParam, Macro, Module, ModuleDef, Static, Struct,
-    TraitAlias, TypeAlias, TypeParam, Union, Variant, VariantDef,
+    Trait, TraitAlias, TypeAlias, TypeParam, Union, Variant, VariantDef,
 };
 
 pub trait HasAttrs {
     fn attrs(self, db: &dyn HirDatabase) -> AttrsWithOwner;
-    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation>;
+    #[doc(hidden)]
-    fn resolve_doc_path(
+    fn attr_id(self) -> AttrDefId;
-        self,
-        db: &dyn HirDatabase,
-        link: &str,
-        ns: Option<Namespace>,
-    ) -> Option<DocLinkDef>;
-}
-
-/// Subset of `ide_db::Definition` that doc links can resolve to.
-pub enum DocLinkDef {
-    ModuleDef(ModuleDef),
-    Field(Field),
-    SelfType(Trait),
 }
 
 macro_rules! impl_has_attrs {
@@ -43,18 +31,8 @@ macro_rules! impl_has_attrs {
                 let def = AttrDefId::$def_id(self.into());
                 db.attrs_with_owner(def)
             }
-            fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+            fn attr_id(self) -> AttrDefId {
-                let def = AttrDefId::$def_id(self.into());
+                AttrDefId::$def_id(self.into())
-                db.attrs(def).docs()
-            }
-            fn resolve_doc_path(
-                self,
-                db: &dyn HirDatabase,
-                link: &str,
-                ns: Option<Namespace>
-            ) -> Option<DocLinkDef> {
-                let def = AttrDefId::$def_id(self.into());
-                resolve_doc_path(db, def, link, ns)
             }
         }
     )*};
@@ -74,6 +52,7 @@ impl_has_attrs![
     (Module, ModuleId),
     (GenericParam, GenericParamId),
     (Impl, ImplId),
+    (ExternCrateDecl, ExternCrateId),
 ];
 
 macro_rules! impl_has_attrs_enum {
@@ -82,16 +61,8 @@ macro_rules! impl_has_attrs_enum {
             fn attrs(self, db: &dyn HirDatabase) -> AttrsWithOwner {
                 $enum::$variant(self).attrs(db)
             }
-            fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+            fn attr_id(self) -> AttrDefId {
-                $enum::$variant(self).docs(db)
+                $enum::$variant(self).attr_id()
-            }
-            fn resolve_doc_path(
-                self,
-                db: &dyn HirDatabase,
-                link: &str,
-                ns: Option<Namespace>
-            ) -> Option<DocLinkDef> {
-                $enum::$variant(self).resolve_doc_path(db, link, ns)
             }
         }
     )*};
@@ -108,70 +79,35 @@ impl HasAttrs for AssocItem {
             AssocItem::TypeAlias(it) => it.attrs(db),
         }
     }
-
+    fn attr_id(self) -> AttrDefId {
-    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
         match self {
-            AssocItem::Function(it) => it.docs(db),
+            AssocItem::Function(it) => it.attr_id(),
-            AssocItem::Const(it) => it.docs(db),
+            AssocItem::Const(it) => it.attr_id(),
-            AssocItem::TypeAlias(it) => it.docs(db),
+            AssocItem::TypeAlias(it) => it.attr_id(),
         }
     }
-
-    fn resolve_doc_path(
-        self,
-        db: &dyn HirDatabase,
-        link: &str,
-        ns: Option<Namespace>,
-    ) -> Option<DocLinkDef> {
-        match self {
-            AssocItem::Function(it) => it.resolve_doc_path(db, link, ns),
-            AssocItem::Const(it) => it.resolve_doc_path(db, link, ns),
-            AssocItem::TypeAlias(it) => it.resolve_doc_path(db, link, ns),
-        }
-    }
-}
-
-impl HasAttrs for ExternCrateDecl {
-    fn attrs(self, db: &dyn HirDatabase) -> AttrsWithOwner {
-        let def = AttrDefId::ExternCrateId(self.into());
-        db.attrs_with_owner(def)
-    }
-    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
-        let crate_docs = self.resolved_crate(db)?.root_module().attrs(db).docs().map(String::from);
-        let def = AttrDefId::ExternCrateId(self.into());
-        let decl_docs = db.attrs(def).docs().map(String::from);
-        match (decl_docs, crate_docs) {
-            (None, None) => None,
-            (Some(decl_docs), None) => Some(decl_docs),
-            (None, Some(crate_docs)) => Some(crate_docs),
-            (Some(mut decl_docs), Some(crate_docs)) => {
-                decl_docs.push('\n');
-                decl_docs.push('\n');
-                decl_docs += &crate_docs;
-                Some(decl_docs)
-            }
-        }
-        .map(Documentation::new)
-    }
-    fn resolve_doc_path(
-        self,
-        db: &dyn HirDatabase,
-        link: &str,
-        ns: Option<Namespace>,
-    ) -> Option<DocLinkDef> {
-        let def = AttrDefId::ExternCrateId(self.into());
-        resolve_doc_path(db, def, link, ns)
-    }
 }
 
 /// Resolves the item `link` points to in the scope of `def`.
-fn resolve_doc_path(
+pub fn resolve_doc_path_on(
     db: &dyn HirDatabase,
-    def: AttrDefId,
+    def: impl HasAttrs,
     link: &str,
     ns: Option<Namespace>,
 ) -> Option<DocLinkDef> {
-    let resolver = match def {
+    // AttrDefId::FieldId(it) => it.parent.resolver(db.upcast()),
+    // AttrDefId::EnumVariantId(it) => it.parent.resolver(db.upcast()),
+
+    resolve_doc_path_on_(db, link, def.attr_id(), ns)
+}
+
+fn resolve_doc_path_on_(
+    db: &dyn HirDatabase,
+    link: &str,
+    attr_id: AttrDefId,
+    ns: Option<Namespace>,
+) -> Option<DocLinkDef> {
+    let resolver = match attr_id {
         AttrDefId::ModuleId(it) => it.resolver(db.upcast()),
         AttrDefId::FieldId(it) => it.parent.resolver(db.upcast()),
         AttrDefId::AdtId(it) => it.resolver(db.upcast()),
@@ -187,12 +123,7 @@ fn resolve_doc_path(
         AttrDefId::UseId(it) => it.resolver(db.upcast()),
         AttrDefId::MacroId(it) => it.resolver(db.upcast()),
         AttrDefId::ExternCrateId(it) => it.resolver(db.upcast()),
-        AttrDefId::GenericParamId(it) => match it {
+        AttrDefId::GenericParamId(_) => return None,
-            GenericParamId::TypeParamId(it) => it.parent(),
-            GenericParamId::ConstParamId(it) => it.parent(),
-            GenericParamId::LifetimeParamId(it) => it.parent,
-        }
-        .resolver(db.upcast()),
     };
 
     let mut modpath = modpath_from_str(db, link)?;

crates/hir/src/diagnostics.rs

@@ -43,6 +43,7 @@ diagnostics![
     MacroExpansionParseError,
     MalformedDerive,
     MismatchedArgCount,
+    MismatchedTupleStructPatArgCount,
     MissingFields,
     MissingMatchArms,
     MissingUnsafe,
@@ -172,7 +173,8 @@ pub struct MalformedDerive {
 
 #[derive(Debug)]
 pub struct NoSuchField {
-    pub field: InFile<AstPtr<ast::RecordExprField>>,
+    pub field: InFile<Either<AstPtr<ast::RecordExprField>, AstPtr<ast::RecordPatField>>>,
+    pub private: bool,
 }
 
 #[derive(Debug)]
@@ -182,6 +184,13 @@ pub struct PrivateAssocItem {
     pub item: AssocItem,
 }
 
+#[derive(Debug)]
+pub struct MismatchedTupleStructPatArgCount {
+    pub expr_or_pat: InFile<Either<AstPtr<ast::Expr>, AstPtr<ast::Pat>>>,
+    pub expected: usize,
+    pub found: usize,
+}
+
 #[derive(Debug)]
 pub struct ExpectedFunction {
     pub call: InFile<AstPtr<ast::Expr>>,

crates/hir/src/lib.rs

@@ -88,13 +88,14 @@ use triomphe::Arc;
 use crate::db::{DefDatabase, HirDatabase};
 
 pub use crate::{
-    attrs::{DocLinkDef, HasAttrs},
+    attrs::{resolve_doc_path_on, HasAttrs},
     diagnostics::{
         AnyDiagnostic, BreakOutsideOfLoop, CaseType, ExpectedFunction, InactiveCode,
         IncoherentImpl, IncorrectCase, InvalidDeriveTarget, MacroDefError, MacroError,
-        MacroExpansionParseError, MalformedDerive, MismatchedArgCount, MissingFields,
+        MacroExpansionParseError, MalformedDerive, MismatchedArgCount,
-        MissingMatchArms, MissingUnsafe, MovedOutOfRef, NeedMut, NoSuchField, PrivateAssocItem,
+        MismatchedTupleStructPatArgCount, MissingFields, MissingMatchArms, MissingUnsafe,
-        PrivateField, ReplaceFilterMapNextWithFindMap, TypeMismatch, TypedHole, UndeclaredLabel,
+        MovedOutOfRef, NeedMut, NoSuchField, PrivateAssocItem, PrivateField,
+        ReplaceFilterMapNextWithFindMap, TypeMismatch, TypedHole, UndeclaredLabel,
         UnimplementedBuiltinMacro, UnreachableLabel, UnresolvedExternCrate, UnresolvedField,
         UnresolvedImport, UnresolvedMacroCall, UnresolvedMethodCall, UnresolvedModule,
         UnresolvedProcMacro, UnusedMut,
@@ -115,7 +116,7 @@ pub use crate::{
 pub use {
     cfg::{CfgAtom, CfgExpr, CfgOptions},
     hir_def::{
-        attr::{builtin::AttributeTemplate, Attrs, AttrsWithOwner, Documentation},
+        attr::{builtin::AttributeTemplate, AttrSourceMap, Attrs, AttrsWithOwner},
         data::adt::StructKind,
         find_path::PrefixKind,
         import_map,
@@ -130,7 +131,7 @@ pub use {
         {AdtId, ModuleDefId},
     },
     hir_expand::{
-        attrs::Attr,
+        attrs::{Attr, AttrId},
         name::{known, Name},
         ExpandResult, HirFileId, InFile, MacroFile, Origin,
     },
@@ -563,8 +564,8 @@ impl Module {
             emit_def_diagnostic(db, acc, diag);
         }
 
-        for decl in self.declarations(db) {
+        for def in self.declarations(db) {
-            match decl {
+            match def {
                 ModuleDef::Module(m) => {
                     // Only add diagnostics from inline modules
                     if def_map[m.id.local_id].origin.is_inline() {
@@ -575,7 +576,7 @@ impl Module {
                     for diag in db.trait_data_with_diagnostics(t.id).1.iter() {
                         emit_def_diagnostic(db, acc, diag);
                     }
-                    acc.extend(decl.diagnostics(db))
+                    acc.extend(def.diagnostics(db))
                 }
                 ModuleDef::Adt(adt) => {
                     match adt {
@@ -599,10 +600,10 @@ impl Module {
                             }
                         }
                     }
-                    acc.extend(decl.diagnostics(db))
+                    acc.extend(def.diagnostics(db))
                 }
                 ModuleDef::Macro(m) => emit_macro_def_diagnostics(db, acc, m),
-                _ => acc.extend(decl.diagnostics(db)),
+                _ => acc.extend(def.diagnostics(db)),
             }
         }
         self.legacy_macros(db).into_iter().for_each(|m| emit_macro_def_diagnostics(db, acc, m));
@@ -1446,6 +1447,7 @@ impl DefWithBody {
     }
 
     pub fn diagnostics(self, db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>) {
+        db.unwind_if_cancelled();
         let krate = self.module(db).id.krate();
 
         let (body, source_map) = db.body_with_source_map(self.into());
@@ -1501,11 +1503,19 @@ impl DefWithBody {
         let infer = db.infer(self.into());
         let source_map = Lazy::new(|| db.body_with_source_map(self.into()).1);
         let expr_syntax = |expr| source_map.expr_syntax(expr).expect("unexpected synthetic");
+        let pat_syntax = |pat| source_map.pat_syntax(pat).expect("unexpected synthetic");
         for d in &infer.diagnostics {
             match d {
-                &hir_ty::InferenceDiagnostic::NoSuchField { expr } => {
+                &hir_ty::InferenceDiagnostic::NoSuchField { field: expr, private } => {
-                    let field = source_map.field_syntax(expr);
+                    let expr_or_pat = match expr {
-                    acc.push(NoSuchField { field }.into())
+                        ExprOrPatId::ExprId(expr) => {
+                            source_map.field_syntax(expr).map(Either::Left)
+                        }
+                        ExprOrPatId::PatId(pat) => {
+                            source_map.pat_field_syntax(pat).map(Either::Right)
+                        }
+                    };
+                    acc.push(NoSuchField { field: expr_or_pat, private }.into())
                 }
                 &hir_ty::InferenceDiagnostic::MismatchedArgCount { call_expr, expected, found } => {
                     acc.push(
@@ -1521,10 +1531,7 @@ impl DefWithBody {
                 &hir_ty::InferenceDiagnostic::PrivateAssocItem { id, item } => {
                     let expr_or_pat = match id {
                         ExprOrPatId::ExprId(expr) => expr_syntax(expr).map(Either::Left),
-                        ExprOrPatId::PatId(pat) => source_map
+                        ExprOrPatId::PatId(pat) => pat_syntax(pat).map(Either::Right),
-                            .pat_syntax(pat)
-                            .expect("unexpected synthetic")
-                            .map(Either::Right),
                     };
                     let item = item.into();
                     acc.push(PrivateAssocItem { expr_or_pat, item }.into())
@@ -1596,6 +1603,23 @@ impl DefWithBody {
                         .into(),
                     )
                 }
+                &hir_ty::InferenceDiagnostic::MismatchedTupleStructPatArgCount {
+                    pat,
+                    expected,
+                    found,
+                } => {
+                    let expr_or_pat = match pat {
+                        ExprOrPatId::ExprId(expr) => expr_syntax(expr).map(Either::Left),
+                        ExprOrPatId::PatId(pat) => source_map
+                            .pat_syntax(pat)
+                            .expect("unexpected synthetic")
+                            .map(|it| it.unwrap_left())
+                            .map(Either::Right),
+                    };
+                    acc.push(
+                        MismatchedTupleStructPatArgCount { expr_or_pat, expected, found }.into(),
+                    )
+                }
             }
         }
         for (pat_or_expr, mismatch) in infer.type_mismatches() {
@@ -4838,3 +4862,10 @@ pub enum ItemContainer {
     ExternBlock(),
     Crate(CrateId),
 }
+
+/// Subset of `ide_db::Definition` that doc links can resolve to.
+pub enum DocLinkDef {
+    ModuleDef(ModuleDef),
+    Field(Field),
+    SelfType(Trait),
+}

crates/hir/src/semantics.rs

@@ -127,165 +127,24 @@ impl<DB> fmt::Debug for Semantics<'_, DB> {
     }
 }
 
+impl<'db, DB> ops::Deref for Semantics<'db, DB> {
+    type Target = SemanticsImpl<'db>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.imp
+    }
+}
+
 impl<'db, DB: HirDatabase> Semantics<'db, DB> {
     pub fn new(db: &DB) -> Semantics<'_, DB> {
         let impl_ = SemanticsImpl::new(db);
         Semantics { db, imp: impl_ }
     }
 
-    pub fn parse(&self, file_id: FileId) -> ast::SourceFile {
-        self.imp.parse(file_id)
-    }
-
-    pub fn parse_or_expand(&self, file_id: HirFileId) -> SyntaxNode {
-        self.imp.parse_or_expand(file_id)
-    }
-
-    pub fn expand(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
-        self.imp.expand(macro_call)
-    }
-
-    /// If `item` has an attribute macro attached to it, expands it.
-    pub fn expand_attr_macro(&self, item: &ast::Item) -> Option<SyntaxNode> {
-        self.imp.expand_attr_macro(item)
-    }
-
-    pub fn expand_derive_as_pseudo_attr_macro(&self, attr: &ast::Attr) -> Option<SyntaxNode> {
-        self.imp.expand_derive_as_pseudo_attr_macro(attr)
-    }
-
-    pub fn resolve_derive_macro(&self, derive: &ast::Attr) -> Option<Vec<Option<Macro>>> {
-        self.imp.resolve_derive_macro(derive)
-    }
-
-    pub fn expand_derive_macro(&self, derive: &ast::Attr) -> Option<Vec<SyntaxNode>> {
-        self.imp.expand_derive_macro(derive)
-    }
-
-    pub fn is_attr_macro_call(&self, item: &ast::Item) -> bool {
-        self.imp.is_attr_macro_call(item)
-    }
-
-    pub fn is_derive_annotated(&self, item: &ast::Adt) -> bool {
-        self.imp.is_derive_annotated(item)
-    }
-
-    /// Expand the macro call with a different token tree, mapping the `token_to_map` down into the
-    /// expansion. `token_to_map` should be a token from the `speculative args` node.
-    pub fn speculative_expand(
-        &self,
-        actual_macro_call: &ast::MacroCall,
-        speculative_args: &ast::TokenTree,
-        token_to_map: SyntaxToken,
-    ) -> Option<(SyntaxNode, SyntaxToken)> {
-        self.imp.speculative_expand(actual_macro_call, speculative_args, token_to_map)
-    }
-
-    /// Expand the macro call with a different item as the input, mapping the `token_to_map` down into the
-    /// expansion. `token_to_map` should be a token from the `speculative args` node.
-    pub fn speculative_expand_attr_macro(
-        &self,
-        actual_macro_call: &ast::Item,
-        speculative_args: &ast::Item,
-        token_to_map: SyntaxToken,
-    ) -> Option<(SyntaxNode, SyntaxToken)> {
-        self.imp.speculative_expand_attr(actual_macro_call, speculative_args, token_to_map)
-    }
-
-    pub fn speculative_expand_derive_as_pseudo_attr_macro(
-        &self,
-        actual_macro_call: &ast::Attr,
-        speculative_args: &ast::Attr,
-        token_to_map: SyntaxToken,
-    ) -> Option<(SyntaxNode, SyntaxToken)> {
-        self.imp.speculative_expand_derive_as_pseudo_attr_macro(
-            actual_macro_call,
-            speculative_args,
-            token_to_map,
-        )
-    }
-
-    /// Descend the token into its macro call if it is part of one, returning the token in the
-    /// expansion that it is associated with. If `offset` points into the token's range, it will
-    /// be considered for the mapping in case of inline format args.
-    pub fn descend_into_macros_single(&self, token: SyntaxToken, offset: TextSize) -> SyntaxToken {
-        self.imp.descend_into_macros_single(token, offset)
-    }
-
-    /// Descend the token into its macro call if it is part of one, returning the tokens in the
-    /// expansion that it is associated with. If `offset` points into the token's range, it will
-    /// be considered for the mapping in case of inline format args.
-    pub fn descend_into_macros(
-        &self,
-        token: SyntaxToken,
-        offset: TextSize,
-    ) -> SmallVec<[SyntaxToken; 1]> {
-        self.imp.descend_into_macros(token, offset)
-    }
-
-    /// Descend the token into macrocalls to all its mapped counterparts that have the same text as the input token.
-    ///
-    /// Returns the original non descended token if none of the mapped counterparts have the same text.
-    pub fn descend_into_macros_with_same_text(
-        &self,
-        token: SyntaxToken,
-        offset: TextSize,
-    ) -> SmallVec<[SyntaxToken; 1]> {
-        self.imp.descend_into_macros_with_same_text(token, offset)
-    }
-
-    pub fn descend_into_macros_with_kind_preference(
-        &self,
-        token: SyntaxToken,
-        offset: TextSize,
-    ) -> SyntaxToken {
-        self.imp.descend_into_macros_with_kind_preference(token, offset)
-    }
-
-    /// Maps a node down by mapping its first and last token down.
-    pub fn descend_node_into_attributes<N: AstNode>(&self, node: N) -> SmallVec<[N; 1]> {
-        self.imp.descend_node_into_attributes(node)
-    }
-
-    /// Search for a definition's source and cache its syntax tree
-    pub fn source<Def: HasSource>(&self, def: Def) -> Option<InFile<Def::Ast>>
-    where
-        Def::Ast: AstNode,
-    {
-        self.imp.source(def)
-    }
-
     pub fn hir_file_for(&self, syntax_node: &SyntaxNode) -> HirFileId {
         self.imp.find_file(syntax_node).file_id
     }
 
-    /// Attempts to map the node out of macro expanded files returning the original file range.
-    /// If upmapping is not possible, this will fall back to the range of the macro call of the
-    /// macro file the node resides in.
-    pub fn original_range(&self, node: &SyntaxNode) -> FileRange {
-        self.imp.original_range(node)
-    }
-
-    /// Attempts to map the node out of macro expanded files returning the original file range.
-    pub fn original_range_opt(&self, node: &SyntaxNode) -> Option<FileRange> {
-        self.imp.original_range_opt(node)
-    }
-
-    /// Attempts to map the node out of macro expanded files.
-    /// This only work for attribute expansions, as other ones do not have nodes as input.
-    pub fn original_ast_node<N: AstNode>(&self, node: N) -> Option<N> {
-        self.imp.original_ast_node(node)
-    }
-    /// Attempts to map the node out of macro expanded files.
-    /// This only work for attribute expansions, as other ones do not have nodes as input.
-    pub fn original_syntax_node(&self, node: &SyntaxNode) -> Option<SyntaxNode> {
-        self.imp.original_syntax_node(node)
-    }
-
-    pub fn diagnostics_display_range(&self, diagnostics: InFile<SyntaxNodePtr>) -> FileRange {
-        self.imp.diagnostics_display_range(diagnostics)
-    }
-
     pub fn token_ancestors_with_macros(
         &self,
         token: SyntaxToken,
@@ -293,19 +152,6 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         token.parent().into_iter().flat_map(move |it| self.ancestors_with_macros(it))
     }
 
-    /// Iterates the ancestors of the given node, climbing up macro expansions while doing so.
-    pub fn ancestors_with_macros(&self, node: SyntaxNode) -> impl Iterator<Item = SyntaxNode> + '_ {
-        self.imp.ancestors_with_macros(node)
-    }
-
-    pub fn ancestors_at_offset_with_macros(
-        &self,
-        node: &SyntaxNode,
-        offset: TextSize,
-    ) -> impl Iterator<Item = SyntaxNode> + '_ {
-        self.imp.ancestors_at_offset_with_macros(node, offset)
-    }
-
     /// Find an AstNode by offset inside SyntaxNode, if it is inside *Macrofile*,
     /// search up until it is of the target AstNode type
     pub fn find_node_at_offset_with_macros<N: AstNode>(
@@ -336,53 +182,6 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.descend_node_at_offset(node, offset).filter_map(|mut it| it.find_map(N::cast))
     }
 
-    pub fn resolve_lifetime_param(&self, lifetime: &ast::Lifetime) -> Option<LifetimeParam> {
-        self.imp.resolve_lifetime_param(lifetime)
-    }
-
-    pub fn resolve_label(&self, lifetime: &ast::Lifetime) -> Option<Label> {
-        self.imp.resolve_label(lifetime)
-    }
-
-    pub fn resolve_type(&self, ty: &ast::Type) -> Option<Type> {
-        self.imp.resolve_type(ty)
-    }
-
-    pub fn resolve_trait(&self, trait_: &ast::Path) -> Option<Trait> {
-        self.imp.resolve_trait(trait_)
-    }
-
-    pub fn expr_adjustments(&self, expr: &ast::Expr) -> Option<Vec<Adjustment>> {
-        self.imp.expr_adjustments(expr)
-    }
-
-    pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<TypeInfo> {
-        self.imp.type_of_expr(expr)
-    }
-
-    pub fn type_of_pat(&self, pat: &ast::Pat) -> Option<TypeInfo> {
-        self.imp.type_of_pat(pat)
-    }
-
-    /// It also includes the changes that binding mode makes in the type. For example in
-    /// `let ref x @ Some(_) = None` the result of `type_of_pat` is `Option<T>` but the result
-    /// of this function is `&mut Option<T>`
-    pub fn type_of_binding_in_pat(&self, pat: &ast::IdentPat) -> Option<Type> {
-        self.imp.type_of_binding_in_pat(pat)
-    }
-
-    pub fn type_of_self(&self, param: &ast::SelfParam) -> Option<Type> {
-        self.imp.type_of_self(param)
-    }
-
-    pub fn pattern_adjustments(&self, pat: &ast::Pat) -> SmallVec<[Type; 1]> {
-        self.imp.pattern_adjustments(pat)
-    }
-
-    pub fn binding_mode_of_pat(&self, pat: &ast::IdentPat) -> Option<BindingMode> {
-        self.imp.binding_mode_of_pat(pat)
-    }
-
     pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
         self.imp.resolve_method_call(call).map(Function::from)
     }
@@ -417,61 +216,10 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.resolve_try_expr(try_expr).map(Function::from)
     }
 
-    pub fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
-        self.imp.resolve_method_call_as_callable(call)
-    }
-
-    pub fn resolve_field(&self, field: &ast::FieldExpr) -> Option<Field> {
-        self.imp.resolve_field(field)
-    }
-
-    pub fn resolve_record_field(
-        &self,
-        field: &ast::RecordExprField,
-    ) -> Option<(Field, Option<Local>, Type)> {
-        self.imp.resolve_record_field(field)
-    }
-
-    pub fn resolve_record_pat_field(&self, field: &ast::RecordPatField) -> Option<(Field, Type)> {
-        self.imp.resolve_record_pat_field(field)
-    }
-
-    pub fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<Macro> {
-        self.imp.resolve_macro_call(macro_call)
-    }
-
-    pub fn is_unsafe_macro_call(&self, macro_call: &ast::MacroCall) -> bool {
-        self.imp.is_unsafe_macro_call(macro_call)
-    }
-
-    pub fn resolve_attr_macro_call(&self, item: &ast::Item) -> Option<Macro> {
-        self.imp.resolve_attr_macro_call(item)
-    }
-
-    pub fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
-        self.imp.resolve_path(path)
-    }
-
     pub fn resolve_variant(&self, record_lit: ast::RecordExpr) -> Option<VariantDef> {
         self.imp.resolve_variant(record_lit).map(VariantDef::from)
     }
 
-    pub fn resolve_bind_pat_to_const(&self, pat: &ast::IdentPat) -> Option<ModuleDef> {
-        self.imp.resolve_bind_pat_to_const(pat)
-    }
-
-    pub fn record_literal_missing_fields(&self, literal: &ast::RecordExpr) -> Vec<(Field, Type)> {
-        self.imp.record_literal_missing_fields(literal)
-    }
-
-    pub fn record_pattern_missing_fields(&self, pattern: &ast::RecordPat) -> Vec<(Field, Type)> {
-        self.imp.record_pattern_missing_fields(pattern)
-    }
-
-    pub fn to_def<T: ToDef>(&self, src: &T) -> Option<T::Def> {
-        self.imp.to_def(src)
-    }
-
     pub fn to_module_def(&self, file: FileId) -> Option<Module> {
         self.imp.to_module_def(file).next()
     }
@@ -479,39 +227,6 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
     pub fn to_module_defs(&self, file: FileId) -> impl Iterator<Item = Module> {
         self.imp.to_module_def(file)
     }
-
-    pub fn scope(&self, node: &SyntaxNode) -> Option<SemanticsScope<'db>> {
-        self.imp.scope(node)
-    }
-
-    pub fn scope_at_offset(
-        &self,
-        node: &SyntaxNode,
-        offset: TextSize,
-    ) -> Option<SemanticsScope<'db>> {
-        self.imp.scope_at_offset(node, offset)
-    }
-
-    pub fn assert_contains_node(&self, node: &SyntaxNode) {
-        self.imp.assert_contains_node(node)
-    }
-
-    pub fn is_unsafe_method_call(&self, method_call_expr: &ast::MethodCallExpr) -> bool {
-        self.imp.is_unsafe_method_call(method_call_expr)
-    }
-
-    pub fn is_unsafe_ref_expr(&self, ref_expr: &ast::RefExpr) -> bool {
-        self.imp.is_unsafe_ref_expr(ref_expr)
-    }
-
-    pub fn is_unsafe_ident_pat(&self, ident_pat: &ast::IdentPat) -> bool {
-        self.imp.is_unsafe_ident_pat(ident_pat)
-    }
-
-    /// Returns `true` if the `node` is inside an `unsafe` context.
-    pub fn is_inside_unsafe(&self, expr: &ast::Expr) -> bool {
-        self.imp.is_inside_unsafe(expr)
-    }
 }
 
 impl<'db> SemanticsImpl<'db> {
@@ -525,32 +240,33 @@ impl<'db> SemanticsImpl<'db> {
         }
     }
 
-    fn parse(&self, file_id: FileId) -> ast::SourceFile {
+    pub fn parse(&self, file_id: FileId) -> ast::SourceFile {
         let tree = self.db.parse(file_id).tree();
         self.cache(tree.syntax().clone(), file_id.into());
         tree
     }
 
-    fn parse_or_expand(&self, file_id: HirFileId) -> SyntaxNode {
+    pub fn parse_or_expand(&self, file_id: HirFileId) -> SyntaxNode {
         let node = self.db.parse_or_expand(file_id);
         self.cache(node.clone(), file_id);
         node
     }
 
-    fn expand(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
+    pub fn expand(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
         let sa = self.analyze_no_infer(macro_call.syntax())?;
         let file_id = sa.expand(self.db, InFile::new(sa.file_id, macro_call))?;
         let node = self.parse_or_expand(file_id);
         Some(node)
     }
 
-    fn expand_attr_macro(&self, item: &ast::Item) -> Option<SyntaxNode> {
+    /// If `item` has an attribute macro attached to it, expands it.
+    pub fn expand_attr_macro(&self, item: &ast::Item) -> Option<SyntaxNode> {
         let src = self.wrap_node_infile(item.clone());
         let macro_call_id = self.with_ctx(|ctx| ctx.item_to_macro_call(src))?;
         Some(self.parse_or_expand(macro_call_id.as_file()))
     }
 
-    fn expand_derive_as_pseudo_attr_macro(&self, attr: &ast::Attr) -> Option<SyntaxNode> {
+    pub fn expand_derive_as_pseudo_attr_macro(&self, attr: &ast::Attr) -> Option<SyntaxNode> {
         let adt = attr.syntax().parent().and_then(ast::Adt::cast)?;
         let src = self.wrap_node_infile(attr.clone());
         let call_id = self.with_ctx(|ctx| {
@@ -559,7 +275,7 @@ impl<'db> SemanticsImpl<'db> {
         Some(self.parse_or_expand(call_id.as_file()))
     }
 
-    fn resolve_derive_macro(&self, attr: &ast::Attr) -> Option<Vec<Option<Macro>>> {
+    pub fn resolve_derive_macro(&self, attr: &ast::Attr) -> Option<Vec<Option<Macro>>> {
         let calls = self.derive_macro_calls(attr)?;
         self.with_ctx(|ctx| {
             Some(
@@ -573,7 +289,7 @@ impl<'db> SemanticsImpl<'db> {
         })
     }
 
-    fn expand_derive_macro(&self, attr: &ast::Attr) -> Option<Vec<SyntaxNode>> {
+    pub fn expand_derive_macro(&self, attr: &ast::Attr) -> Option<Vec<SyntaxNode>> {
         let res: Vec<_> = self
             .derive_macro_calls(attr)?
             .into_iter()
@@ -598,19 +314,21 @@ impl<'db> SemanticsImpl<'db> {
         })
     }
 
-    fn is_derive_annotated(&self, adt: &ast::Adt) -> bool {
+    pub fn is_derive_annotated(&self, adt: &ast::Adt) -> bool {
         let file_id = self.find_file(adt.syntax()).file_id;
         let adt = InFile::new(file_id, adt);
         self.with_ctx(|ctx| ctx.has_derives(adt))
     }
 
-    fn is_attr_macro_call(&self, item: &ast::Item) -> bool {
+    pub fn is_attr_macro_call(&self, item: &ast::Item) -> bool {
         let file_id = self.find_file(item.syntax()).file_id;
         let src = InFile::new(file_id, item.clone());
         self.with_ctx(|ctx| ctx.item_to_macro_call(src).is_some())
     }
 
-    fn speculative_expand(
+    /// Expand the macro call with a different token tree, mapping the `token_to_map` down into the
+    /// expansion. `token_to_map` should be a token from the `speculative args` node.
+    pub fn speculative_expand(
         &self,
         actual_macro_call: &ast::MacroCall,
         speculative_args: &ast::TokenTree,
@@ -633,7 +351,9 @@ impl<'db> SemanticsImpl<'db> {
         )
     }
 
-    fn speculative_expand_attr(
+    /// Expand the macro call with a different item as the input, mapping the `token_to_map` down into the
+    /// expansion. `token_to_map` should be a token from the `speculative args` node.
+    pub fn speculative_expand_attr_macro(
         &self,
         actual_macro_call: &ast::Item,
         speculative_args: &ast::Item,
@@ -649,7 +369,7 @@ impl<'db> SemanticsImpl<'db> {
         )
     }
 
-    fn speculative_expand_derive_as_pseudo_attr_macro(
+    pub fn speculative_expand_derive_as_pseudo_attr_macro(
         &self,
         actual_macro_call: &ast::Attr,
         speculative_args: &ast::Attr,
@@ -668,8 +388,9 @@ impl<'db> SemanticsImpl<'db> {
         )
     }
 
-    // This might not be the correct way to do this, but it works for now
+    /// Maps a node down by mapping its first and last token down.
-    fn descend_node_into_attributes<N: AstNode>(&self, node: N) -> SmallVec<[N; 1]> {
+    pub fn descend_node_into_attributes<N: AstNode>(&self, node: N) -> SmallVec<[N; 1]> {
+        // This might not be the correct way to do this, but it works for now
         let mut res = smallvec![];
         let tokens = (|| {
             let first = skip_trivia_token(node.syntax().first_token()?, Direction::Next)?;
@@ -723,7 +444,10 @@ impl<'db> SemanticsImpl<'db> {
         res
     }
 
-    fn descend_into_macros(
+    /// Descend the token into its macro call if it is part of one, returning the tokens in the
+    /// expansion that it is associated with. If `offset` points into the token's range, it will
+    /// be considered for the mapping in case of inline format args.
+    pub fn descend_into_macros(
         &self,
         token: SyntaxToken,
         offset: TextSize,
@@ -736,7 +460,10 @@ impl<'db> SemanticsImpl<'db> {
         res
     }
 
-    fn descend_into_macros_with_same_text(
+    /// Descend the token into macrocalls to all its mapped counterparts that have the same text as the input token.
+    ///
+    /// Returns the original non descended token if none of the mapped counterparts have the same text.
+    pub fn descend_into_macros_with_same_text(
         &self,
         token: SyntaxToken,
         offset: TextSize,
@@ -755,7 +482,7 @@ impl<'db> SemanticsImpl<'db> {
         res
     }
 
-    fn descend_into_macros_with_kind_preference(
+    pub fn descend_into_macros_with_kind_preference(
         &self,
         token: SyntaxToken,
         offset: TextSize,
@@ -785,7 +512,10 @@ impl<'db> SemanticsImpl<'db> {
         res.unwrap_or(token)
     }
 
-    fn descend_into_macros_single(&self, token: SyntaxToken, offset: TextSize) -> SyntaxToken {
+    /// Descend the token into its macro call if it is part of one, returning the token in the
+    /// expansion that it is associated with. If `offset` points into the token's range, it will
+    /// be considered for the mapping in case of inline format args.
+    pub fn descend_into_macros_single(&self, token: SyntaxToken, offset: TextSize) -> SyntaxToken {
         let mut res = token.clone();
         self.descend_into_macros_impl(token, offset, &mut |InFile { value, .. }| {
             res = value;
@@ -995,17 +725,23 @@ impl<'db> SemanticsImpl<'db> {
             })
     }
 
-    fn original_range(&self, node: &SyntaxNode) -> FileRange {
+    /// Attempts to map the node out of macro expanded files returning the original file range.
+    /// If upmapping is not possible, this will fall back to the range of the macro call of the
+    /// macro file the node resides in.
+    pub fn original_range(&self, node: &SyntaxNode) -> FileRange {
         let node = self.find_file(node);
         node.original_file_range(self.db.upcast())
     }
 
-    fn original_range_opt(&self, node: &SyntaxNode) -> Option<FileRange> {
+    /// Attempts to map the node out of macro expanded files returning the original file range.
+    pub fn original_range_opt(&self, node: &SyntaxNode) -> Option<FileRange> {
         let node = self.find_file(node);
         node.original_file_range_opt(self.db.upcast())
     }
 
-    fn original_ast_node<N: AstNode>(&self, node: N) -> Option<N> {
+    /// Attempts to map the node out of macro expanded files.
+    /// This only work for attribute expansions, as other ones do not have nodes as input.
+    pub fn original_ast_node<N: AstNode>(&self, node: N) -> Option<N> {
         self.wrap_node_infile(node).original_ast_node(self.db.upcast()).map(
             |InFile { file_id, value }| {
                 self.cache(find_root(value.syntax()), file_id);
@@ -1014,7 +750,9 @@ impl<'db> SemanticsImpl<'db> {
         )
     }
 
-    fn original_syntax_node(&self, node: &SyntaxNode) -> Option<SyntaxNode> {
+    /// Attempts to map the node out of macro expanded files.
+    /// This only work for attribute expansions, as other ones do not have nodes as input.
+    pub fn original_syntax_node(&self, node: &SyntaxNode) -> Option<SyntaxNode> {
         let InFile { file_id, .. } = self.find_file(node);
         InFile::new(file_id, node).original_syntax_node(self.db.upcast()).map(
             |InFile { file_id, value }| {
@@ -1024,7 +762,7 @@ impl<'db> SemanticsImpl<'db> {
         )
     }
 
-    fn diagnostics_display_range(&self, src: InFile<SyntaxNodePtr>) -> FileRange {
+    pub fn diagnostics_display_range(&self, src: InFile<SyntaxNodePtr>) -> FileRange {
         let root = self.parse_or_expand(src.file_id);
         let node = src.map(|it| it.to_node(&root));
         node.as_ref().original_file_range(self.db.upcast())
@@ -1037,7 +775,8 @@ impl<'db> SemanticsImpl<'db> {
         token.parent().into_iter().flat_map(move |parent| self.ancestors_with_macros(parent))
     }
 
-    fn ancestors_with_macros(
+    /// Iterates the ancestors of the given node, climbing up macro expansions while doing so.
+    pub fn ancestors_with_macros(
         &self,
         node: SyntaxNode,
     ) -> impl Iterator<Item = SyntaxNode> + Clone + '_ {
@@ -1055,7 +794,7 @@ impl<'db> SemanticsImpl<'db> {
         .map(|it| it.value)
     }
 
-    fn ancestors_at_offset_with_macros(
+    pub fn ancestors_at_offset_with_macros(
         &self,
         node: &SyntaxNode,
         offset: TextSize,
@@ -1065,7 +804,7 @@ impl<'db> SemanticsImpl<'db> {
             .kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len())
     }
 
-    fn resolve_lifetime_param(&self, lifetime: &ast::Lifetime) -> Option<LifetimeParam> {
+    pub fn resolve_lifetime_param(&self, lifetime: &ast::Lifetime) -> Option<LifetimeParam> {
         let text = lifetime.text();
         let lifetime_param = lifetime.syntax().ancestors().find_map(|syn| {
             let gpl = ast::AnyHasGenericParams::cast(syn)?.generic_param_list()?;
@@ -1076,7 +815,7 @@ impl<'db> SemanticsImpl<'db> {
         ToDef::to_def(self, src)
     }
 
-    fn resolve_label(&self, lifetime: &ast::Lifetime) -> Option<Label> {
+    pub fn resolve_label(&self, lifetime: &ast::Lifetime) -> Option<Label> {
         let text = lifetime.text();
         let label = lifetime.syntax().ancestors().find_map(|syn| {
             let label = match_ast! {
@@ -1098,7 +837,7 @@ impl<'db> SemanticsImpl<'db> {
         ToDef::to_def(self, src)
     }
 
-    fn resolve_type(&self, ty: &ast::Type) -> Option<Type> {
+    pub fn resolve_type(&self, ty: &ast::Type) -> Option<Type> {
         let analyze = self.analyze(ty.syntax())?;
         let ctx = LowerCtx::with_file_id(self.db.upcast(), analyze.file_id);
         let ty = hir_ty::TyLoweringContext::new(
@@ -1110,7 +849,7 @@ impl<'db> SemanticsImpl<'db> {
         Some(Type::new_with_resolver(self.db, &analyze.resolver, ty))
     }
 
-    fn resolve_trait(&self, path: &ast::Path) -> Option<Trait> {
+    pub fn resolve_trait(&self, path: &ast::Path) -> Option<Trait> {
         let analyze = self.analyze(path.syntax())?;
         let hygiene = hir_expand::hygiene::Hygiene::new(self.db.upcast(), analyze.file_id);
         let ctx = LowerCtx::with_hygiene(self.db.upcast(), &hygiene);
@@ -1121,7 +860,7 @@ impl<'db> SemanticsImpl<'db> {
         }
     }
 
-    fn expr_adjustments(&self, expr: &ast::Expr) -> Option<Vec<Adjustment>> {
+    pub fn expr_adjustments(&self, expr: &ast::Expr) -> Option<Vec<Adjustment>> {
         let mutability = |m| match m {
             hir_ty::Mutability::Not => Mutability::Shared,
             hir_ty::Mutability::Mut => Mutability::Mut,
@@ -1165,33 +904,36 @@ impl<'db> SemanticsImpl<'db> {
         })
     }
 
-    fn type_of_expr(&self, expr: &ast::Expr) -> Option<TypeInfo> {
+    pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<TypeInfo> {
         self.analyze(expr.syntax())?
             .type_of_expr(self.db, expr)
             .map(|(ty, coerced)| TypeInfo { original: ty, adjusted: coerced })
     }
 
-    fn type_of_pat(&self, pat: &ast::Pat) -> Option<TypeInfo> {
+    pub fn type_of_pat(&self, pat: &ast::Pat) -> Option<TypeInfo> {
         self.analyze(pat.syntax())?
             .type_of_pat(self.db, pat)
             .map(|(ty, coerced)| TypeInfo { original: ty, adjusted: coerced })
     }
 
-    fn type_of_binding_in_pat(&self, pat: &ast::IdentPat) -> Option<Type> {
+    /// It also includes the changes that binding mode makes in the type. For example in
+    /// `let ref x @ Some(_) = None` the result of `type_of_pat` is `Option<T>` but the result
+    /// of this function is `&mut Option<T>`
+    pub fn type_of_binding_in_pat(&self, pat: &ast::IdentPat) -> Option<Type> {
         self.analyze(pat.syntax())?.type_of_binding_in_pat(self.db, pat)
     }
 
-    fn type_of_self(&self, param: &ast::SelfParam) -> Option<Type> {
+    pub fn type_of_self(&self, param: &ast::SelfParam) -> Option<Type> {
         self.analyze(param.syntax())?.type_of_self(self.db, param)
     }
 
-    fn pattern_adjustments(&self, pat: &ast::Pat) -> SmallVec<[Type; 1]> {
+    pub fn pattern_adjustments(&self, pat: &ast::Pat) -> SmallVec<[Type; 1]> {
         self.analyze(pat.syntax())
             .and_then(|it| it.pattern_adjustments(self.db, pat))
             .unwrap_or_default()
     }
 
-    fn binding_mode_of_pat(&self, pat: &ast::IdentPat) -> Option<BindingMode> {
+    pub fn binding_mode_of_pat(&self, pat: &ast::IdentPat) -> Option<BindingMode> {
         self.analyze(pat.syntax())?.binding_mode_of_pat(self.db, pat)
     }
 
@@ -1226,32 +968,32 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(try_expr.syntax())?.resolve_try_expr(self.db, try_expr)
     }
 
-    fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
+    pub fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
         self.analyze(call.syntax())?.resolve_method_call_as_callable(self.db, call)
     }
 
-    fn resolve_field(&self, field: &ast::FieldExpr) -> Option<Field> {
+    pub fn resolve_field(&self, field: &ast::FieldExpr) -> Option<Field> {
         self.analyze(field.syntax())?.resolve_field(self.db, field)
     }
 
-    fn resolve_record_field(
+    pub fn resolve_record_field(
         &self,
         field: &ast::RecordExprField,
     ) -> Option<(Field, Option<Local>, Type)> {
         self.analyze(field.syntax())?.resolve_record_field(self.db, field)
     }
 
-    fn resolve_record_pat_field(&self, field: &ast::RecordPatField) -> Option<(Field, Type)> {
+    pub fn resolve_record_pat_field(&self, field: &ast::RecordPatField) -> Option<(Field, Type)> {
         self.analyze(field.syntax())?.resolve_record_pat_field(self.db, field)
     }
 
-    fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<Macro> {
+    pub fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<Macro> {
         let sa = self.analyze(macro_call.syntax())?;
         let macro_call = self.find_file(macro_call.syntax()).with_value(macro_call);
         sa.resolve_macro_call(self.db, macro_call)
     }
 
-    fn is_unsafe_macro_call(&self, macro_call: &ast::MacroCall) -> bool {
+    pub fn is_unsafe_macro_call(&self, macro_call: &ast::MacroCall) -> bool {
         let sa = match self.analyze(macro_call.syntax()) {
             Some(it) => it,
             None => return false,
@@ -1260,7 +1002,7 @@ impl<'db> SemanticsImpl<'db> {
         sa.is_unsafe_macro_call(self.db, macro_call)
     }
 
-    fn resolve_attr_macro_call(&self, item: &ast::Item) -> Option<Macro> {
+    pub fn resolve_attr_macro_call(&self, item: &ast::Item) -> Option<Macro> {
         let item_in_file = self.wrap_node_infile(item.clone());
         let id = self.with_ctx(|ctx| {
             let macro_call_id = ctx.item_to_macro_call(item_in_file)?;
@@ -1269,7 +1011,7 @@ impl<'db> SemanticsImpl<'db> {
         Some(Macro { id })
     }
 
-    fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
+    pub fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
         self.analyze(path.syntax())?.resolve_path(self.db, path)
     }
 
@@ -1277,17 +1019,17 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(record_lit.syntax())?.resolve_variant(self.db, record_lit)
     }
 
-    fn resolve_bind_pat_to_const(&self, pat: &ast::IdentPat) -> Option<ModuleDef> {
+    pub fn resolve_bind_pat_to_const(&self, pat: &ast::IdentPat) -> Option<ModuleDef> {
         self.analyze(pat.syntax())?.resolve_bind_pat_to_const(self.db, pat)
     }
 
-    fn record_literal_missing_fields(&self, literal: &ast::RecordExpr) -> Vec<(Field, Type)> {
+    pub fn record_literal_missing_fields(&self, literal: &ast::RecordExpr) -> Vec<(Field, Type)> {
         self.analyze(literal.syntax())
             .and_then(|it| it.record_literal_missing_fields(self.db, literal))
             .unwrap_or_default()
     }
 
-    fn record_pattern_missing_fields(&self, pattern: &ast::RecordPat) -> Vec<(Field, Type)> {
+    pub fn record_pattern_missing_fields(&self, pattern: &ast::RecordPat) -> Vec<(Field, Type)> {
         self.analyze(pattern.syntax())
             .and_then(|it| it.record_pattern_missing_fields(self.db, pattern))
             .unwrap_or_default()
@@ -1299,7 +1041,7 @@ impl<'db> SemanticsImpl<'db> {
         f(&mut ctx)
     }
 
-    fn to_def<T: ToDef>(&self, src: &T) -> Option<T::Def> {
+    pub fn to_def<T: ToDef>(&self, src: &T) -> Option<T::Def> {
         let src = self.find_file(src.syntax()).with_value(src).cloned();
         T::to_def(self, src)
     }
@@ -1308,7 +1050,7 @@ impl<'db> SemanticsImpl<'db> {
         self.with_ctx(|ctx| ctx.file_to_def(file)).into_iter().map(Module::from)
     }
 
-    fn scope(&self, node: &SyntaxNode) -> Option<SemanticsScope<'db>> {
+    pub fn scope(&self, node: &SyntaxNode) -> Option<SemanticsScope<'db>> {
         self.analyze_no_infer(node).map(|SourceAnalyzer { file_id, resolver, .. }| SemanticsScope {
             db: self.db,
             file_id,
@@ -1316,7 +1058,11 @@ impl<'db> SemanticsImpl<'db> {
         })
     }
 
-    fn scope_at_offset(&self, node: &SyntaxNode, offset: TextSize) -> Option<SemanticsScope<'db>> {
+    pub fn scope_at_offset(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> Option<SemanticsScope<'db>> {
         self.analyze_with_offset_no_infer(node, offset).map(
             |SourceAnalyzer { file_id, resolver, .. }| SemanticsScope {
                 db: self.db,
@@ -1326,7 +1072,8 @@ impl<'db> SemanticsImpl<'db> {
         )
     }
 
-    fn source<Def: HasSource>(&self, def: Def) -> Option<InFile<Def::Ast>>
+    /// Search for a definition's source and cache its syntax tree
+    pub fn source<Def: HasSource>(&self, def: Def) -> Option<InFile<Def::Ast>>
     where
         Def::Ast: AstNode,
     {
@@ -1391,7 +1138,7 @@ impl<'db> SemanticsImpl<'db> {
         assert!(prev == None || prev == Some(file_id))
     }
 
-    fn assert_contains_node(&self, node: &SyntaxNode) {
+    pub fn assert_contains_node(&self, node: &SyntaxNode) {
         self.find_file(node);
     }
 
@@ -1427,7 +1174,7 @@ impl<'db> SemanticsImpl<'db> {
         InFile::new(file_id, node)
     }
 
-    fn is_unsafe_method_call(&self, method_call_expr: &ast::MethodCallExpr) -> bool {
+    pub fn is_unsafe_method_call(&self, method_call_expr: &ast::MethodCallExpr) -> bool {
         method_call_expr
             .receiver()
             .and_then(|expr| {
@@ -1450,7 +1197,7 @@ impl<'db> SemanticsImpl<'db> {
             .unwrap_or(false)
     }
 
-    fn is_unsafe_ref_expr(&self, ref_expr: &ast::RefExpr) -> bool {
+    pub fn is_unsafe_ref_expr(&self, ref_expr: &ast::RefExpr) -> bool {
         ref_expr
             .expr()
             .and_then(|expr| {
@@ -1469,7 +1216,7 @@ impl<'db> SemanticsImpl<'db> {
         // more than it should with the current implementation.
     }
 
-    fn is_unsafe_ident_pat(&self, ident_pat: &ast::IdentPat) -> bool {
+    pub fn is_unsafe_ident_pat(&self, ident_pat: &ast::IdentPat) -> bool {
         if ident_pat.ref_token().is_none() {
             return false;
         }
@@ -1512,7 +1259,8 @@ impl<'db> SemanticsImpl<'db> {
             .unwrap_or(false)
     }
 
-    fn is_inside_unsafe(&self, expr: &ast::Expr) -> bool {
+    /// Returns `true` if the `node` is inside an `unsafe` context.
+    pub fn is_inside_unsafe(&self, expr: &ast::Expr) -> bool {
         let Some(enclosing_item) =
             expr.syntax().ancestors().find_map(Either::<ast::Item, ast::Variant>::cast)
         else {

crates/ide-assists/src/handlers/bind_unused_param.rs

@@ -0,0 +1,159 @@
+use crate::assist_context::{AssistContext, Assists};
+use ide_db::{
+    assists::{AssistId, AssistKind},
+    defs::Definition,
+    LineIndexDatabase,
+};
+use syntax::{
+    ast::{self, edit_in_place::Indent},
+    AstNode,
+};
+
+// Assist: bind_unused_param
+//
+// Binds unused function parameter to an underscore.
+//
+// ```
+// fn some_function(x: i32$0) {}
+// ```
+// ->
+// ```
+// fn some_function(x: i32) {
+//     let _ = x;
+// }
+// ```
+pub(crate) fn bind_unused_param(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
+    let param: ast::Param = ctx.find_node_at_offset()?;
+
+    let Some(ast::Pat::IdentPat(ident_pat)) = param.pat() else { return None };
+
+    let param_def = {
+        let local = ctx.sema.to_def(&ident_pat)?;
+        Definition::Local(local)
+    };
+    if param_def.usages(&ctx.sema).at_least_one() {
+        cov_mark::hit!(keep_used);
+        return None;
+    }
+
+    let func = param.syntax().ancestors().find_map(ast::Fn::cast)?;
+    let stmt_list = func.body()?.stmt_list()?;
+    let l_curly_range = stmt_list.l_curly_token()?.text_range();
+    let r_curly_range = stmt_list.r_curly_token()?.text_range();
+
+    acc.add(
+        AssistId("bind_unused_param", AssistKind::QuickFix),
+        &format!("Bind as `let _ = {};`", &ident_pat),
+        param.syntax().text_range(),
+        |builder| {
+            let line_index = ctx.db().line_index(ctx.file_id());
+
+            let indent = func.indent_level();
+            let text_indent = indent + 1;
+            let mut text = format!("\n{text_indent}let _ = {ident_pat};");
+
+            let left_line = line_index.line_col(l_curly_range.end()).line;
+            let right_line = line_index.line_col(r_curly_range.start()).line;
+
+            if left_line == right_line {
+                cov_mark::hit!(single_line);
+                text.push_str(&format!("\n{indent}"));
+            }
+
+            builder.insert(l_curly_range.end(), text);
+        },
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn bind_unused_empty_block() {
+        cov_mark::check!(single_line);
+        check_assist(
+            bind_unused_param,
+            r#"
+fn foo($0y: i32) {}
+"#,
+            r#"
+fn foo(y: i32) {
+    let _ = y;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn bind_unused_empty_block_with_newline() {
+        check_assist(
+            bind_unused_param,
+            r#"
+fn foo($0y: i32) {
+}
+"#,
+            r#"
+fn foo(y: i32) {
+    let _ = y;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn bind_unused_generic() {
+        check_assist(
+            bind_unused_param,
+            r#"
+fn foo<T>($0y: T)
+where T : Default {
+}
+"#,
+            r#"
+fn foo<T>(y: T)
+where T : Default {
+    let _ = y;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn trait_impl() {
+        check_assist(
+            bind_unused_param,
+            r#"
+trait Trait {
+    fn foo(x: i32);
+}
+impl Trait for () {
+    fn foo($0x: i32) {}
+}
+"#,
+            r#"
+trait Trait {
+    fn foo(x: i32);
+}
+impl Trait for () {
+    fn foo(x: i32) {
+        let _ = x;
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn keep_used() {
+        cov_mark::check!(keep_used);
+        check_assist_not_applicable(
+            bind_unused_param,
+            r#"
+fn foo(x: i32, $0y: i32) { y; }
+"#,
+        );
+    }
+}

crates/ide-assists/src/handlers/convert_bool_then.rs

@@ -103,7 +103,6 @@ pub(crate) fn convert_if_to_bool_then(acc: &mut Assists, ctx: &AssistContext<'_>
                 cond,
                 ast::Expr::BinExpr(_)
                     | ast::Expr::BlockExpr(_)
-                    | ast::Expr::BoxExpr(_)
                     | ast::Expr::BreakExpr(_)
                     | ast::Expr::CastExpr(_)
                     | ast::Expr::ClosureExpr(_)

crates/ide-assists/src/handlers/extract_expressions_from_format_string.rs

@@ -15,26 +15,13 @@ use syntax::{ast, AstNode, AstToken, NodeOrToken, SyntaxKind::COMMA, TextRange};
 // Move an expression out of a format string.
 //
 // ```
-// macro_rules! format_args {
+// # //- minicore: fmt
-//     ($lit:literal $(tt:tt)*) => { 0 },
-// }
-// macro_rules! print {
-//     ($($arg:tt)*) => (std::io::_print(format_args!($($arg)*)));
-// }
-//
 // fn main() {
 //     print!("{var} {x + 1}$0");
 // }
 // ```
 // ->
 // ```
-// macro_rules! format_args {
-//     ($lit:literal $(tt:tt)*) => { 0 },
-// }
-// macro_rules! print {
-//     ($($arg:tt)*) => (std::io::_print(format_args!($($arg)*)));
-// }
-//
 // fn main() {
 //     print!("{var} {}"$0, x + 1);
 // }
@@ -158,37 +145,21 @@ mod tests {
     use super::*;
     use crate::tests::check_assist;
 
-    const MACRO_DECL: &'static str = r#"
-macro_rules! format_args {
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
-macro_rules! print {
-    ($($arg:tt)*) => (std::io::_print(format_args!($($arg)*)));
-}
-"#;
-
-    fn add_macro_decl(s: &'static str) -> String {
-        MACRO_DECL.to_string() + s
-    }
-
     #[test]
     fn multiple_middle_arg() {
         check_assist(
             extract_expressions_from_format_string,
-            &add_macro_decl(
+            r#"
-                r#"
+//- minicore: fmt
 fn main() {
     print!("{} {x + 1:b} {}$0", y + 2, 2);
 }
 "#,
-            ),
+            r#"
-            &add_macro_decl(
-                r#"
 fn main() {
     print!("{} {:b} {}"$0, y + 2, x + 1, 2);
 }
 "#,
-            ),
         );
     }
 
@@ -196,20 +167,17 @@ fn main() {
     fn single_arg() {
         check_assist(
             extract_expressions_from_format_string,
-            &add_macro_decl(
+            r#"
-                r#"
+//- minicore: fmt
 fn main() {
     print!("{obj.value:b}$0",);
 }
 "#,
-            ),
+            r#"
-            &add_macro_decl(
-                r#"
 fn main() {
     print!("{:b}"$0, obj.value);
 }
 "#,
-            ),
         );
     }
 
@@ -217,20 +185,17 @@ fn main() {
     fn multiple_middle_placeholders_arg() {
         check_assist(
             extract_expressions_from_format_string,
-            &add_macro_decl(
+            r#"
-                r#"
+//- minicore: fmt
 fn main() {
     print!("{} {x + 1:b} {} {}$0", y + 2, 2);
 }
 "#,
-            ),
+            r#"
-            &add_macro_decl(
-                r#"
 fn main() {
     print!("{} {:b} {} {}"$0, y + 2, x + 1, 2, $1);
 }
 "#,
-            ),
         );
     }
 
@@ -238,20 +203,17 @@ fn main() {
     fn multiple_trailing_args() {
         check_assist(
             extract_expressions_from_format_string,
-            &add_macro_decl(
+            r#"
-                r#"
+//- minicore: fmt
 fn main() {
     print!("{:b} {x + 1:b} {Struct(1, 2)}$0", 1);
 }
 "#,
-            ),
+            r#"
-            &add_macro_decl(
-                r#"
 fn main() {
     print!("{:b} {:b} {}"$0, 1, x + 1, Struct(1, 2));
 }
 "#,
-            ),
         );
     }
 
@@ -259,20 +221,17 @@ fn main() {
     fn improper_commas() {
         check_assist(
             extract_expressions_from_format_string,
-            &add_macro_decl(
+            r#"
-                r#"
+//- minicore: fmt
 fn main() {
     print!("{} {x + 1:b} {Struct(1, 2)}$0", 1,);
 }
 "#,
-            ),
+            r#"
-            &add_macro_decl(
-                r#"
 fn main() {
     print!("{} {:b} {}"$0, 1, x + 1, Struct(1, 2));
 }
 "#,
-            ),
         );
     }
 
@@ -280,20 +239,17 @@ fn main() {
     fn nested_tt() {
         check_assist(
             extract_expressions_from_format_string,
-            &add_macro_decl(
+            r#"
-                r#"
+//- minicore: fmt
 fn main() {
     print!("My name is {} {x$0 + x}", stringify!(Paperino))
 }
 "#,
-            ),
+            r#"
-            &add_macro_decl(
-                r#"
 fn main() {
     print!("My name is {} {}"$0, stringify!(Paperino), x + x)
 }
 "#,
-            ),
         );
     }
 
@@ -301,22 +257,19 @@ fn main() {
     fn extract_only_expressions() {
         check_assist(
             extract_expressions_from_format_string,
-            &add_macro_decl(
+            r#"
-                r#"
+//- minicore: fmt
 fn main() {
     let var = 1 + 1;
     print!("foobar {var} {var:?} {x$0 + x}")
 }
 "#,
-            ),
+            r#"
-            &add_macro_decl(
-                r#"
 fn main() {
     let var = 1 + 1;
     print!("foobar {var} {var:?} {}"$0, x + x)
 }
 "#,
-            ),
         );
     }
 }

crates/ide-assists/src/handlers/extract_function.rs

@@ -531,7 +531,7 @@ impl FunctionBody {
 
     fn extracted_from_trait_impl(&self) -> bool {
         match self.node().ancestors().find_map(ast::Impl::cast) {
-            Some(c) => return c.trait_().is_some(),
+            Some(c) => c.trait_().is_some(),
             None => false,
         }
     }
@@ -1048,23 +1048,17 @@ impl GenericParent {
 fn generic_parents(parent: &SyntaxNode) -> Vec<GenericParent> {
     let mut list = Vec::new();
     if let Some(parent_item) = parent.ancestors().find_map(ast::Item::cast) {
-        match parent_item {
+        if let ast::Item::Fn(ref fn_) = parent_item {
-            ast::Item::Fn(ref fn_) => {
+            if let Some(parent_parent) =
-                if let Some(parent_parent) = parent_item
+                parent_item.syntax().parent().and_then(|it| it.parent()).and_then(ast::Item::cast)
-                    .syntax()
+            {
-                    .parent()
+                match parent_parent {
-                    .and_then(|it| it.parent())
+                    ast::Item::Impl(impl_) => list.push(GenericParent::Impl(impl_)),
-                    .and_then(ast::Item::cast)
+                    ast::Item::Trait(trait_) => list.push(GenericParent::Trait(trait_)),
-                {
+                    _ => (),
-                    match parent_parent {
-                        ast::Item::Impl(impl_) => list.push(GenericParent::Impl(impl_)),
-                        ast::Item::Trait(trait_) => list.push(GenericParent::Trait(trait_)),
-                        _ => (),
-                    }
                 }
-                list.push(GenericParent::Fn(fn_.clone()));
             }
-            _ => (),
+            list.push(GenericParent::Fn(fn_.clone()));
         }
     }
     list
@@ -1728,7 +1722,7 @@ fn make_body(
     let block = match &fun.body {
         FunctionBody::Expr(expr) => {
             let expr = rewrite_body_segment(ctx, &fun.params, &handler, expr.syntax());
-            let expr = ast::Expr::cast(expr).unwrap();
+            let expr = ast::Expr::cast(expr).expect("Body segment should be an expr");
             match expr {
                 ast::Expr::BlockExpr(block) => {
                     // If the extracted expression is itself a block, there is no need to wrap it inside another block.
@@ -1868,9 +1862,8 @@ fn with_tail_expr(block: ast::BlockExpr, tail_expr: ast::Expr) -> ast::BlockExpr
 
     if let Some(stmt_list) = block.stmt_list() {
         stmt_list.syntax().children_with_tokens().for_each(|node_or_token| {
-            match &node_or_token {
+            if let syntax::NodeOrToken::Token(_) = &node_or_token {
-                syntax::NodeOrToken::Token(_) => elements.push(node_or_token),
+                elements.push(node_or_token)
-                _ => (),
             };
         });
     }
@@ -1934,12 +1927,18 @@ fn fix_param_usages(ctx: &AssistContext<'_>, params: &[Param], syntax: &SyntaxNo
                 Some(ast::Expr::RefExpr(node))
                     if param.kind() == ParamKind::MutRef && node.mut_token().is_some() =>
                 {
-                    ted::replace(node.syntax(), node.expr().unwrap().syntax());
+                    ted::replace(
+                        node.syntax(),
+                        node.expr().expect("RefExpr::expr() cannot be None").syntax(),
+                    );
                 }
                 Some(ast::Expr::RefExpr(node))
                     if param.kind() == ParamKind::SharedRef && node.mut_token().is_none() =>
                 {
-                    ted::replace(node.syntax(), node.expr().unwrap().syntax());
+                    ted::replace(
+                        node.syntax(),
+                        node.expr().expect("RefExpr::expr() cannot be None").syntax(),
+                    );
                 }
                 Some(_) | None => {
                     let p = &make::expr_prefix(T![*], usage.clone()).clone_for_update();

crates/ide-assists/src/handlers/into_to_qualified_from.rs

@@ -0,0 +1,205 @@
+use hir::{AsAssocItem, HirDisplay};
+use ide_db::{
+    assists::{AssistId, AssistKind},
+    famous_defs::FamousDefs,
+};
+use syntax::{ast, AstNode};
+
+use crate::assist_context::{AssistContext, Assists};
+
+// Assist: into_to_qualified_from
+//
+// Convert an `into` method call to a fully qualified `from` call.
+//
+// ```
+// //- minicore: from
+// struct B;
+// impl From<i32> for B {
+//     fn from(a: i32) -> Self {
+//        B
+//     }
+// }
+//
+// fn main() -> () {
+//     let a = 3;
+//     let b: B = a.in$0to();
+// }
+// ```
+// ->
+// ```
+// struct B;
+// impl From<i32> for B {
+//     fn from(a: i32) -> Self {
+//        B
+//     }
+// }
+//
+// fn main() -> () {
+//     let a = 3;
+//     let b: B = B::from(a);
+// }
+// ```
+pub(crate) fn into_to_qualified_from(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
+    let method_call: ast::MethodCallExpr = ctx.find_node_at_offset()?;
+    let nameref = method_call.name_ref()?;
+    let receiver = method_call.receiver()?;
+    let db = ctx.db();
+    let sema = &ctx.sema;
+    let fnc = sema.resolve_method_call(&method_call)?;
+    let scope = sema.scope(method_call.syntax())?;
+    // Check if the method call refers to Into trait.
+    if fnc.as_assoc_item(db)?.containing_trait_impl(db)?
+        == FamousDefs(sema, scope.krate()).core_convert_Into()?
+    {
+        let type_call = sema.type_of_expr(&method_call.clone().into())?;
+        let type_call_disp =
+            type_call.adjusted().display_source_code(db, scope.module().into(), true).ok()?;
+
+        acc.add(
+            AssistId("into_to_qualified_from", AssistKind::Generate),
+            "Convert `into` to fully qualified `from`",
+            nameref.syntax().text_range(),
+            |edit| {
+                edit.replace(
+                    method_call.syntax().text_range(),
+                    format!("{}::from({})", type_call_disp, receiver),
+                );
+            },
+        );
+    }
+
+    Some(())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::check_assist;
+
+    use super::into_to_qualified_from;
+
+    #[test]
+    fn two_types_in_same_mod() {
+        check_assist(
+            into_to_qualified_from,
+            r#"
+//- minicore: from
+struct A;
+struct B;
+impl From<A> for B {
+    fn from(a: A) -> Self {
+        B
+    }
+}
+
+fn main() -> () {
+    let a: A = A;
+    let b: B = a.in$0to();
+}"#,
+            r#"
+struct A;
+struct B;
+impl From<A> for B {
+    fn from(a: A) -> Self {
+        B
+    }
+}
+
+fn main() -> () {
+    let a: A = A;
+    let b: B = B::from(a);
+}"#,
+        )
+    }
+
+    #[test]
+    fn fromed_in_child_mod_imported() {
+        check_assist(
+            into_to_qualified_from,
+            r#"
+//- minicore: from
+use C::B;
+
+struct A;
+
+mod C {
+    use crate::A;
+
+    pub(super) struct B;
+    impl From<A> for B {
+        fn from(a: A) -> Self {
+            B
+        }
+    }
+}
+
+fn main() -> () {
+    let a: A = A;
+    let b: B = a.in$0to();
+}"#,
+            r#"
+use C::B;
+
+struct A;
+
+mod C {
+    use crate::A;
+
+    pub(super) struct B;
+    impl From<A> for B {
+        fn from(a: A) -> Self {
+            B
+        }
+    }
+}
+
+fn main() -> () {
+    let a: A = A;
+    let b: B = B::from(a);
+}"#,
+        )
+    }
+
+    #[test]
+    fn fromed_in_child_mod_not_imported() {
+        check_assist(
+            into_to_qualified_from,
+            r#"
+//- minicore: from
+struct A;
+
+mod C {
+    use crate::A;
+
+    pub(super) struct B;
+    impl From<A> for B {
+        fn from(a: A) -> Self {
+            B
+        }
+    }
+}
+
+fn main() -> () {
+    let a: A = A;
+    let b: C::B = a.in$0to();
+}"#,
+            r#"
+struct A;
+
+mod C {
+    use crate::A;
+
+    pub(super) struct B;
+    impl From<A> for B {
+        fn from(a: A) -> Self {
+            B
+        }
+    }
+}
+
+fn main() -> () {
+    let a: A = A;
+    let b: C::B = C::B::from(a);
+}"#,
+        )
+    }
+}

crates/ide-assists/src/handlers/promote_local_to_const.rs

@@ -76,12 +76,19 @@ pub(crate) fn promote_local_to_const(acc: &mut Assists, ctx: &AssistContext<'_>)
             let name = to_upper_snake_case(&name.to_string());
             let usages = Definition::Local(local).usages(&ctx.sema).all();
             if let Some(usages) = usages.references.get(&ctx.file_id()) {
-                let name = make::name_ref(&name);
+                let name_ref = make::name_ref(&name);
 
                 for usage in usages {
                     let Some(usage) = usage.name.as_name_ref().cloned() else { continue };
-                    let usage = edit.make_mut(usage);
+                    if let Some(record_field) = ast::RecordExprField::for_name_ref(&usage) {
-                    ted::replace(usage.syntax(), name.clone_for_update().syntax());
+                        let record_field = edit.make_mut(record_field);
+                        let name_expr =
+                            make::expr_path(make::path_from_text(&name)).clone_for_update();
+                        record_field.replace_expr(name_expr);
+                    } else {
+                        let usage = edit.make_mut(usage);
+                        ted::replace(usage.syntax(), name_ref.clone_for_update().syntax());
+                    }
                 }
             }
 
@@ -120,8 +127,7 @@ fn is_body_const(sema: &Semantics<'_, RootDatabase>, expr: &ast::Expr) -> bool {
                 is_const &=
                     sema.resolve_method_call(&call).map(|it| it.is_const(sema.db)).unwrap_or(true)
             }
-            ast::Expr::BoxExpr(_)
+            ast::Expr::ForExpr(_)
-            | ast::Expr::ForExpr(_)
             | ast::Expr::ReturnExpr(_)
             | ast::Expr::TryExpr(_)
             | ast::Expr::YieldExpr(_)
@@ -179,6 +185,33 @@ fn foo() {
         );
     }
 
+    #[test]
+    fn usage_in_field_shorthand() {
+        check_assist(
+            promote_local_to_const,
+            r"
+struct Foo {
+    bar: usize,
+}
+
+fn main() {
+    let $0bar = 0;
+    let foo = Foo { bar };
+}
+",
+            r"
+struct Foo {
+    bar: usize,
+}
+
+fn main() {
+    const $0BAR: usize = 0;
+    let foo = Foo { bar: BAR };
+}
+",
+        )
+    }
+
     #[test]
     fn not_applicable_non_const_meth_call() {
         cov_mark::check!(promote_local_non_const);

crates/ide-assists/src/handlers/remove_dbg.rs

@@ -113,10 +113,7 @@ fn compute_dbg_replacement(macro_expr: ast::MacroExpr) -> Option<(TextRange, Opt
                 Some(parent) => match (expr, parent) {
                     (ast::Expr::CastExpr(_), ast::Expr::CastExpr(_)) => false,
                     (
-                        ast::Expr::BoxExpr(_)
+                        ast::Expr::PrefixExpr(_) | ast::Expr::RefExpr(_) | ast::Expr::MacroExpr(_),
-                        | ast::Expr::PrefixExpr(_)
-                        | ast::Expr::RefExpr(_)
-                        | ast::Expr::MacroExpr(_),
                         ast::Expr::AwaitExpr(_)
                         | ast::Expr::CallExpr(_)
                         | ast::Expr::CastExpr(_)

crates/ide-assists/src/handlers/wrap_return_type_in_result.rs

@@ -48,6 +48,11 @@ pub(crate) fn wrap_return_type_in_result(acc: &mut Assists, ctx: &AssistContext<
         return None;
     }
 
+    let new_result_ty =
+        make::ext::ty_result(type_ref.clone(), make::ty_placeholder()).clone_for_update();
+    let generic_args = new_result_ty.syntax().descendants().find_map(ast::GenericArgList::cast)?;
+    let last_genarg = generic_args.generic_args().last()?;
+
     acc.add(
         AssistId("wrap_return_type_in_result", AssistKind::RefactorRewrite),
         "Wrap return type in Result",
@@ -75,19 +80,12 @@ pub(crate) fn wrap_return_type_in_result(acc: &mut Assists, ctx: &AssistContext<
                 ted::replace(ret_expr_arg.syntax(), ok_wrapped.syntax());
             }
 
-            let new_result_ty =
-                make::ext::ty_result(type_ref.clone(), make::ty_placeholder()).clone_for_update();
             let old_result_ty = edit.make_mut(type_ref.clone());
 
             ted::replace(old_result_ty.syntax(), new_result_ty.syntax());
 
             if let Some(cap) = ctx.config.snippet_cap {
-                let generic_args = new_result_ty
+                edit.add_placeholder_snippet(cap, last_genarg);
-                    .syntax()
-                    .descendants()
-                    .find_map(ast::GenericArgList::cast)
-                    .unwrap();
-                edit.add_placeholder_snippet(cap, generic_args.generic_args().last().unwrap());
             }
         },
     )

crates/ide-assists/src/lib.rs

@@ -114,6 +114,7 @@ mod handlers {
     mod add_turbo_fish;
     mod apply_demorgan;
     mod auto_import;
+    mod bind_unused_param;
     mod change_visibility;
     mod convert_bool_then;
     mod convert_comment_block;
@@ -211,6 +212,7 @@ mod handlers {
     mod unwrap_result_return_type;
     mod unqualify_method_call;
     mod wrap_return_type_in_result;
+    mod into_to_qualified_from;
 
     pub(crate) fn all() -> &'static [Handler] {
         &[
@@ -224,6 +226,7 @@ mod handlers {
             add_turbo_fish::add_turbo_fish,
             apply_demorgan::apply_demorgan,
             auto_import::auto_import,
+            bind_unused_param::bind_unused_param,
             change_visibility::change_visibility,
             convert_bool_then::convert_bool_then_to_if,
             convert_bool_then::convert_if_to_bool_then,
@@ -274,6 +277,7 @@ mod handlers {
             inline_local_variable::inline_local_variable,
             inline_type_alias::inline_type_alias,
             inline_type_alias::inline_type_alias_uses,
+            into_to_qualified_from::into_to_qualified_from,
             introduce_named_generic::introduce_named_generic,
             introduce_named_lifetime::introduce_named_lifetime,
             invert_if::invert_if,

crates/ide-assists/src/tests/generated.rs

@@ -265,6 +265,21 @@ pub mod std { pub mod collections { pub struct HashMap { } } }
     )
 }
 
+#[test]
+fn doctest_bind_unused_param() {
+    check_doc_test(
+        "bind_unused_param",
+        r#####"
+fn some_function(x: i32$0) {}
+"#####,
+        r#####"
+fn some_function(x: i32) {
+    let _ = x;
+}
+"#####,
+    )
+}
+
 #[test]
 fn doctest_change_visibility() {
     check_doc_test(
@@ -694,25 +709,12 @@ fn doctest_extract_expressions_from_format_string() {
     check_doc_test(
         "extract_expressions_from_format_string",
         r#####"
-macro_rules! format_args {
+//- minicore: fmt
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
-macro_rules! print {
-    ($($arg:tt)*) => (std::io::_print(format_args!($($arg)*)));
-}
-
 fn main() {
     print!("{var} {x + 1}$0");
 }
 "#####,
         r#####"
-macro_rules! format_args {
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
-macro_rules! print {
-    ($($arg:tt)*) => (std::io::_print(format_args!($($arg)*)));
-}
-
 fn main() {
     print!("{var} {}"$0, x + 1);
 }
@@ -1754,6 +1756,40 @@ fn foo() {
     )
 }
 
+#[test]
+fn doctest_into_to_qualified_from() {
+    check_doc_test(
+        "into_to_qualified_from",
+        r#####"
+//- minicore: from
+struct B;
+impl From<i32> for B {
+    fn from(a: i32) -> Self {
+       B
+    }
+}
+
+fn main() -> () {
+    let a = 3;
+    let b: B = a.in$0to();
+}
+"#####,
+        r#####"
+struct B;
+impl From<i32> for B {
+    fn from(a: i32) -> Self {
+       B
+    }
+}
+
+fn main() -> () {
+    let a = 3;
+    let b: B = B::from(a);
+}
+"#####,
+    )
+}
+
 #[test]
 fn doctest_introduce_named_generic() {
     check_doc_test(

crates/ide-assists/src/utils/suggest_name.rs

@@ -103,7 +103,6 @@ pub(crate) fn for_variable(expr: &ast::Expr, sema: &Semantics<'_, RootDatabase>)
 
         match expr {
             ast::Expr::RefExpr(inner) => next_expr = inner.expr(),
-            ast::Expr::BoxExpr(inner) => next_expr = inner.expr(),
             ast::Expr::AwaitExpr(inner) => next_expr = inner.expr(),
             // ast::Expr::BlockExpr(block) => expr = block.tail_expr(),
             ast::Expr::CastExpr(inner) => next_expr = inner.expr(),

crates/ide-completion/src/completions/attribute/cfg.rs

@@ -1,10 +1,8 @@
 //! Completion for cfg
 
-use std::iter;
-
 use ide_db::SymbolKind;
 use itertools::Itertools;
-use syntax::SyntaxKind;
+use syntax::{algo, ast::Ident, AstToken, Direction, NodeOrToken, SyntaxKind};
 
 use crate::{completions::Completions, context::CompletionContext, CompletionItem};
 
@@ -15,31 +13,44 @@ pub(crate) fn complete_cfg(acc: &mut Completions, ctx: &CompletionContext<'_>) {
         acc.add(completion.build(ctx.db));
     };
 
-    let previous = iter::successors(ctx.original_token.prev_token(), |t| {
+    // FIXME: Move this into context/analysis.rs
-        (matches!(t.kind(), SyntaxKind::EQ) || t.kind().is_trivia())
+    let previous = ctx
-            .then(|| t.prev_token())
+        .original_token
-            .flatten()
+        .prev_token()
-    })
+        .and_then(|it| {
-    .find(|t| matches!(t.kind(), SyntaxKind::IDENT));
+            if matches!(it.kind(), SyntaxKind::EQ) {
+                Some(it.into())
+            } else {
+                algo::non_trivia_sibling(it.into(), Direction::Prev)
+            }
+        })
+        .filter(|t| matches!(t.kind(), SyntaxKind::EQ))
+        .and_then(|it| algo::non_trivia_sibling(it.prev_sibling_or_token()?, Direction::Prev))
+        .map(|it| match it {
+            NodeOrToken::Node(_) => None,
+            NodeOrToken::Token(t) => Ident::cast(t),
+        });
+    match previous {
+        Some(None) => (),
+        Some(Some(p)) => match p.text() {
+            "target_arch" => KNOWN_ARCH.iter().copied().for_each(add_completion),
+            "target_env" => KNOWN_ENV.iter().copied().for_each(add_completion),
+            "target_os" => KNOWN_OS.iter().copied().for_each(add_completion),
+            "target_vendor" => KNOWN_VENDOR.iter().copied().for_each(add_completion),
+            "target_endian" => ["little", "big"].into_iter().for_each(add_completion),
+            name => ctx.krate.potential_cfg(ctx.db).get_cfg_values(name).cloned().for_each(|s| {
+                let insert_text = format!(r#""{s}""#);
+                let mut item = CompletionItem::new(SymbolKind::BuiltinAttr, ctx.source_range(), s);
+                item.insert_text(insert_text);
 
-    match previous.as_ref().map(|p| p.text()) {
+                acc.add(item.build(ctx.db));
-        Some("target_arch") => KNOWN_ARCH.iter().copied().for_each(add_completion),
+            }),
-        Some("target_env") => KNOWN_ENV.iter().copied().for_each(add_completion),
+        },
-        Some("target_os") => KNOWN_OS.iter().copied().for_each(add_completion),
-        Some("target_vendor") => KNOWN_VENDOR.iter().copied().for_each(add_completion),
-        Some("target_endian") => ["little", "big"].into_iter().for_each(add_completion),
-        Some(name) => ctx.krate.potential_cfg(ctx.db).get_cfg_values(name).cloned().for_each(|s| {
-            let insert_text = format!(r#""{s}""#);
-            let mut item = CompletionItem::new(SymbolKind::BuiltinAttr, ctx.source_range(), s);
-            item.insert_text(insert_text);
-
-            acc.add(item.build(ctx.db));
-        }),
         None => ctx.krate.potential_cfg(ctx.db).get_cfg_keys().cloned().unique().for_each(|s| {
             let item = CompletionItem::new(SymbolKind::BuiltinAttr, ctx.source_range(), s);
             acc.add(item.build(ctx.db));
         }),
-    };
+    }
 }
 
 const KNOWN_ARCH: [&str; 20] = [

crates/ide-completion/src/completions/attribute/derive.rs

@@ -1,6 +1,6 @@
 //! Completion for derives
-use hir::{HasAttrs, ScopeDef};
+use hir::ScopeDef;
-use ide_db::SymbolKind;
+use ide_db::{documentation::HasDocs, SymbolKind};
 use itertools::Itertools;
 use syntax::SmolStr;
 

crates/ide-completion/src/completions/attribute/lint.rs

@@ -1,5 +1,5 @@
 //! Completion for lints
-use ide_db::{generated::lints::Lint, SymbolKind};
+use ide_db::{documentation::Documentation, generated::lints::Lint, SymbolKind};
 use syntax::ast;
 
 use crate::{context::CompletionContext, item::CompletionItem, Completions};
@@ -55,7 +55,7 @@ pub(super) fn complete_lint(
             _ => name.to_owned(),
         };
         let mut item = CompletionItem::new(SymbolKind::Attribute, ctx.source_range(), label);
-        item.documentation(hir::Documentation::new(description.to_owned()));
+        item.documentation(Documentation::new(description.to_owned()));
         item.add_to(acc, ctx.db)
     }
 }

crates/ide-completion/src/completions/extern_crate.rs

@@ -1,7 +1,7 @@
 //! Completion for extern crates
 
-use hir::{HasAttrs, Name};
+use hir::Name;
-use ide_db::SymbolKind;
+use ide_db::{documentation::HasDocs, SymbolKind};
 
 use crate::{context::CompletionContext, CompletionItem, CompletionItemKind};
 

crates/ide-completion/src/completions/format_string.rs

@@ -51,9 +51,7 @@ mod tests {
     fn works_when_wrapped() {
         check(
             r#"
-macro_rules! format_args {
+//- minicore: fmt
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
 macro_rules! print {
     ($($arg:tt)*) => (std::io::_print(format_args!($($arg)*)));
 }
@@ -70,9 +68,7 @@ fn main() {
     fn no_completion_without_brace() {
         check(
             r#"
-macro_rules! format_args {
+//- minicore: fmt
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
 fn main() {
     let foobar = 1;
     format_args!("f$0");
@@ -87,18 +83,13 @@ fn main() {
         check_edit(
             "foobar",
             r#"
-macro_rules! format_args {
+//- minicore: fmt
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
 fn main() {
     let foobar = 1;
     format_args!("{f$0");
 }
 "#,
             r#"
-macro_rules! format_args {
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
 fn main() {
     let foobar = 1;
     format_args!("{foobar");
@@ -108,18 +99,13 @@ fn main() {
         check_edit(
             "foobar",
             r#"
-macro_rules! format_args {
+//- minicore: fmt
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
 fn main() {
     let foobar = 1;
     format_args!("{$0");
 }
 "#,
             r#"
-macro_rules! format_args {
-    ($lit:literal $(tt:tt)*) => { 0 },
-}
 fn main() {
     let foobar = 1;
     format_args!("{foobar");

crates/ide-completion/src/completions/item_list/trait_impl.rs

@@ -33,8 +33,8 @@
 
 use hir::{self, HasAttrs};
 use ide_db::{
-    path_transform::PathTransform, syntax_helpers::insert_whitespace_into_node,
+    documentation::HasDocs, path_transform::PathTransform,
-    traits::get_missing_assoc_items, SymbolKind,
+    syntax_helpers::insert_whitespace_into_node, traits::get_missing_assoc_items, SymbolKind,
 };
 use syntax::{
     ast::{self, edit_in_place::AttrsOwnerEdit, HasTypeBounds},

crates/ide-completion/src/completions/postfix.rs

@@ -2,8 +2,12 @@
 
 mod format_like;
 
-use hir::{Documentation, HasAttrs};
+use ide_db::{
-use ide_db::{imports::insert_use::ImportScope, ty_filter::TryEnum, SnippetCap};
+    documentation::{Documentation, HasDocs},
+    imports::insert_use::ImportScope,
+    ty_filter::TryEnum,
+    SnippetCap,
+};
 use syntax::{
     ast::{self, make, AstNode, AstToken},
     SyntaxKind::{BLOCK_EXPR, EXPR_STMT, FOR_EXPR, IF_EXPR, LOOP_EXPR, STMT_LIST, WHILE_EXPR},

crates/ide-completion/src/completions/snippet.rs

@@ -1,7 +1,6 @@
 //! This file provides snippet completions, like `pd` => `eprintln!(...)`.
 
-use hir::Documentation;
+use ide_db::{documentation::Documentation, imports::insert_use::ImportScope, SnippetCap};
-use ide_db::{imports::insert_use::ImportScope, SnippetCap};
 
 use crate::{
     context::{ExprCtx, ItemListKind, PathCompletionCtx, Qualified},

crates/ide-completion/src/item.rs

@@ -2,8 +2,11 @@
 
 use std::fmt;
 
-use hir::{Documentation, Mutability};
+use hir::Mutability;
-use ide_db::{imports::import_assets::LocatedImport, RootDatabase, SnippetCap, SymbolKind};
+use ide_db::{
+    documentation::Documentation, imports::import_assets::LocatedImport, RootDatabase, SnippetCap,
+    SymbolKind,
+};
 use itertools::Itertools;
 use smallvec::SmallVec;
 use stdx::{impl_from, never};

crates/ide-completion/src/render.rs

@@ -12,7 +12,10 @@ pub(crate) mod literal;
 
 use hir::{AsAssocItem, HasAttrs, HirDisplay, ScopeDef};
 use ide_db::{
-    helpers::item_name, imports::import_assets::LocatedImport, RootDatabase, SnippetCap, SymbolKind,
+    documentation::{Documentation, HasDocs},
+    helpers::item_name,
+    imports::import_assets::LocatedImport,
+    RootDatabase, SnippetCap, SymbolKind,
 };
 use syntax::{AstNode, SmolStr, SyntaxKind, TextRange};
 
@@ -114,7 +117,7 @@ impl<'a> RenderContext<'a> {
     }
 
     // FIXME: remove this
-    fn docs(&self, def: impl HasAttrs) -> Option<hir::Documentation> {
+    fn docs(&self, def: impl HasDocs) -> Option<Documentation> {
         def.docs(self.db())
     }
 }
@@ -409,7 +412,7 @@ fn res_to_kind(resolution: ScopeDef) -> CompletionItemKind {
     }
 }
 
-fn scope_def_docs(db: &RootDatabase, resolution: ScopeDef) -> Option<hir::Documentation> {
+fn scope_def_docs(db: &RootDatabase, resolution: ScopeDef) -> Option<Documentation> {
     use hir::ModuleDef::*;
     match resolution {
         ScopeDef::ModuleDef(Module(it)) => it.docs(db),

crates/ide-completion/src/render/literal.rs

@@ -1,7 +1,10 @@
 //! Renderer for `enum` variants.
 
-use hir::{db::HirDatabase, Documentation, HasAttrs, StructKind};
+use hir::{db::HirDatabase, StructKind};
-use ide_db::SymbolKind;
+use ide_db::{
+    documentation::{Documentation, HasDocs},
+    SymbolKind,
+};
 
 use crate::{
     context::{CompletionContext, PathCompletionCtx, PathKind},

crates/ide-completion/src/render/macro_.rs

@@ -1,7 +1,7 @@
 //! Renderer for macro invocations.
 
-use hir::{Documentation, HirDisplay};
+use hir::HirDisplay;
-use ide_db::SymbolKind;
+use ide_db::{documentation::Documentation, SymbolKind};
 use syntax::SmolStr;
 
 use crate::{

crates/ide-completion/src/render/pattern.rs

@@ -1,7 +1,7 @@
 //! Renderer for patterns.
 
-use hir::{db::HirDatabase, HasAttrs, Name, StructKind};
+use hir::{db::HirDatabase, Name, StructKind};
-use ide_db::SnippetCap;
+use ide_db::{documentation::HasDocs, SnippetCap};
 use itertools::Itertools;
 use syntax::SmolStr;
 
@@ -103,7 +103,7 @@ fn build_completion(
     label: SmolStr,
     lookup: SmolStr,
     pat: String,
-    def: impl HasAttrs + Copy,
+    def: impl HasDocs + Copy,
     adt_ty: hir::Type,
     // Missing in context of match statement completions
     is_variant_missing: bool,

crates/ide-completion/src/tests/attribute.rs

@@ -66,11 +66,6 @@ struct Foo;
     )
 }
 
-#[test]
-fn inside_nested_attr() {
-    check(r#"#[cfg($0)]"#, expect![[]])
-}
-
 #[test]
 fn with_existing_attr() {
     check(
@@ -635,6 +630,32 @@ struct Foo;
 mod cfg {
     use super::*;
 
+    #[test]
+    fn inside_cfg() {
+        check(
+            r#"
+//- /main.rs cfg:test,dbg=false,opt_level=2
+#[cfg($0)]
+"#,
+            expect![[r#"
+                ba dbg
+                ba opt_level
+                ba test
+            "#]],
+        );
+        check(
+            r#"
+//- /main.rs cfg:test,dbg=false,opt_level=2
+#[cfg(b$0)]
+"#,
+            expect![[r#"
+                ba dbg
+                ba opt_level
+                ba test
+            "#]],
+        );
+    }
+
     #[test]
     fn cfg_target_endian() {
         check(
@@ -644,6 +665,13 @@ mod cfg {
                 ba little
             "#]],
         );
+        check(
+            r#"#[cfg(target_endian = b$0"#,
+            expect![[r#"
+                ba big
+                ba little
+            "#]],
+        );
     }
 }
 

crates/ide-db/src/documentation.rs

@@ -0,0 +1,281 @@
+//! Documentation attribute related utilties.
+use either::Either;
+use hir::{
+    db::{DefDatabase, HirDatabase},
+    resolve_doc_path_on, AttrId, AttrSourceMap, AttrsWithOwner, HasAttrs, InFile,
+};
+use itertools::Itertools;
+use syntax::{
+    ast::{self, IsString},
+    AstToken,
+};
+use text_edit::{TextRange, TextSize};
+
+/// Holds documentation
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Documentation(String);
+
+impl Documentation {
+    pub fn new(s: String) -> Self {
+        Documentation(s)
+    }
+
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+impl From<Documentation> for String {
+    fn from(Documentation(string): Documentation) -> Self {
+        string
+    }
+}
+
+pub trait HasDocs: HasAttrs {
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation>;
+    fn resolve_doc_path(
+        self,
+        db: &dyn HirDatabase,
+        link: &str,
+        ns: Option<hir::Namespace>,
+    ) -> Option<hir::DocLinkDef>;
+}
+/// A struct to map text ranges from [`Documentation`] back to TextRanges in the syntax tree.
+#[derive(Debug)]
+pub struct DocsRangeMap {
+    source_map: AttrSourceMap,
+    // (docstring-line-range, attr_index, attr-string-range)
+    // a mapping from the text range of a line of the [`Documentation`] to the attribute index and
+    // the original (untrimmed) syntax doc line
+    mapping: Vec<(TextRange, AttrId, TextRange)>,
+}
+
+impl DocsRangeMap {
+    /// Maps a [`TextRange`] relative to the documentation string back to its AST range
+    pub fn map(&self, range: TextRange) -> Option<InFile<TextRange>> {
+        let found = self.mapping.binary_search_by(|(probe, ..)| probe.ordering(range)).ok()?;
+        let (line_docs_range, idx, original_line_src_range) = self.mapping[found];
+        if !line_docs_range.contains_range(range) {
+            return None;
+        }
+
+        let relative_range = range - line_docs_range.start();
+
+        let InFile { file_id, value: source } = self.source_map.source_of_id(idx);
+        match source {
+            Either::Left(attr) => {
+                let string = get_doc_string_in_attr(attr)?;
+                let text_range = string.open_quote_text_range()?;
+                let range = TextRange::at(
+                    text_range.end() + original_line_src_range.start() + relative_range.start(),
+                    string.syntax().text_range().len().min(range.len()),
+                );
+                Some(InFile { file_id, value: range })
+            }
+            Either::Right(comment) => {
+                let text_range = comment.syntax().text_range();
+                let range = TextRange::at(
+                    text_range.start()
+                        + TextSize::try_from(comment.prefix().len()).ok()?
+                        + original_line_src_range.start()
+                        + relative_range.start(),
+                    text_range.len().min(range.len()),
+                );
+                Some(InFile { file_id, value: range })
+            }
+        }
+    }
+}
+
+pub fn docs_with_rangemap(
+    db: &dyn DefDatabase,
+    attrs: &AttrsWithOwner,
+) -> Option<(Documentation, DocsRangeMap)> {
+    let docs =
+        attrs.by_key("doc").attrs().filter_map(|attr| attr.string_value().map(|s| (s, attr.id)));
+    let indent = doc_indent(attrs);
+    let mut buf = String::new();
+    let mut mapping = Vec::new();
+    for (doc, idx) in docs {
+        if !doc.is_empty() {
+            let mut base_offset = 0;
+            for raw_line in doc.split('\n') {
+                let line = raw_line.trim_end();
+                let line_len = line.len();
+                let (offset, line) = match line.char_indices().nth(indent) {
+                    Some((offset, _)) => (offset, &line[offset..]),
+                    None => (0, line),
+                };
+                let buf_offset = buf.len();
+                buf.push_str(line);
+                mapping.push((
+                    TextRange::new(buf_offset.try_into().ok()?, buf.len().try_into().ok()?),
+                    idx,
+                    TextRange::at(
+                        (base_offset + offset).try_into().ok()?,
+                        line_len.try_into().ok()?,
+                    ),
+                ));
+                buf.push('\n');
+                base_offset += raw_line.len() + 1;
+            }
+        } else {
+            buf.push('\n');
+        }
+    }
+    buf.pop();
+    if buf.is_empty() {
+        None
+    } else {
+        Some((Documentation(buf), DocsRangeMap { mapping, source_map: attrs.source_map(db) }))
+    }
+}
+
+pub fn docs_from_attrs(attrs: &hir::Attrs) -> Option<String> {
+    let docs = attrs.by_key("doc").attrs().filter_map(|attr| attr.string_value());
+    let indent = doc_indent(attrs);
+    let mut buf = String::new();
+    for doc in docs {
+        // str::lines doesn't yield anything for the empty string
+        if !doc.is_empty() {
+            buf.extend(Itertools::intersperse(
+                doc.lines().map(|line| {
+                    line.char_indices()
+                        .nth(indent)
+                        .map_or(line, |(offset, _)| &line[offset..])
+                        .trim_end()
+                }),
+                "\n",
+            ));
+        }
+        buf.push('\n');
+    }
+    buf.pop();
+    if buf.is_empty() {
+        None
+    } else {
+        Some(buf)
+    }
+}
+
+macro_rules! impl_has_docs {
+    ($($def:ident,)*) => {$(
+        impl HasDocs for hir::$def {
+            fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+                docs_from_attrs(&self.attrs(db)).map(Documentation)
+            }
+            fn resolve_doc_path(
+                self,
+                db: &dyn HirDatabase,
+                link: &str,
+                ns: Option<hir::Namespace>
+            ) -> Option<hir::DocLinkDef> {
+                resolve_doc_path_on(db, self, link, ns)
+            }
+        }
+    )*};
+}
+
+impl_has_docs![
+    Variant, Field, Static, Const, Trait, TraitAlias, TypeAlias, Macro, Function, Adt, Module,
+    Impl,
+];
+
+macro_rules! impl_has_docs_enum {
+    ($($variant:ident),* for $enum:ident) => {$(
+        impl HasDocs for hir::$variant {
+            fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+                hir::$enum::$variant(self).docs(db)
+            }
+            fn resolve_doc_path(
+                self,
+                db: &dyn HirDatabase,
+                link: &str,
+                ns: Option<hir::Namespace>
+            ) -> Option<hir::DocLinkDef> {
+                hir::$enum::$variant(self).resolve_doc_path(db, link, ns)
+            }
+        }
+    )*};
+}
+
+impl_has_docs_enum![Struct, Union, Enum for Adt];
+
+impl HasDocs for hir::AssocItem {
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+        match self {
+            hir::AssocItem::Function(it) => it.docs(db),
+            hir::AssocItem::Const(it) => it.docs(db),
+            hir::AssocItem::TypeAlias(it) => it.docs(db),
+        }
+    }
+
+    fn resolve_doc_path(
+        self,
+        db: &dyn HirDatabase,
+        link: &str,
+        ns: Option<hir::Namespace>,
+    ) -> Option<hir::DocLinkDef> {
+        match self {
+            hir::AssocItem::Function(it) => it.resolve_doc_path(db, link, ns),
+            hir::AssocItem::Const(it) => it.resolve_doc_path(db, link, ns),
+            hir::AssocItem::TypeAlias(it) => it.resolve_doc_path(db, link, ns),
+        }
+    }
+}
+
+impl HasDocs for hir::ExternCrateDecl {
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+        let crate_docs =
+            docs_from_attrs(&self.resolved_crate(db)?.root_module().attrs(db)).map(String::from);
+        let decl_docs = docs_from_attrs(&self.attrs(db)).map(String::from);
+        match (decl_docs, crate_docs) {
+            (None, None) => None,
+            (Some(decl_docs), None) => Some(decl_docs),
+            (None, Some(crate_docs)) => Some(crate_docs),
+            (Some(mut decl_docs), Some(crate_docs)) => {
+                decl_docs.push('\n');
+                decl_docs.push('\n');
+                decl_docs += &crate_docs;
+                Some(decl_docs)
+            }
+        }
+        .map(Documentation::new)
+    }
+    fn resolve_doc_path(
+        self,
+        db: &dyn HirDatabase,
+        link: &str,
+        ns: Option<hir::Namespace>,
+    ) -> Option<hir::DocLinkDef> {
+        resolve_doc_path_on(db, self, link, ns)
+    }
+}
+
+fn get_doc_string_in_attr(it: &ast::Attr) -> Option<ast::String> {
+    match it.expr() {
+        // #[doc = lit]
+        Some(ast::Expr::Literal(lit)) => match lit.kind() {
+            ast::LiteralKind::String(it) => Some(it),
+            _ => None,
+        },
+        // #[cfg_attr(..., doc = "", ...)]
+        None => {
+            // FIXME: See highlight injection for what to do here
+            None
+        }
+        _ => None,
+    }
+}
+
+fn doc_indent(attrs: &hir::Attrs) -> usize {
+    attrs
+        .by_key("doc")
+        .attrs()
+        .filter_map(|attr| attr.string_value())
+        .flat_map(|s| s.lines())
+        .filter(|line| !line.chars().all(|c| c.is_whitespace()))
+        .map(|line| line.chars().take_while(|c| c.is_whitespace()).count())
+        .min()
+        .unwrap_or(0)
+}

crates/ide-db/src/lib.rs

@@ -22,6 +22,7 @@ pub mod symbol_index;
 pub mod traits;
 pub mod ty_filter;
 pub mod use_trivial_constructor;
+pub mod documentation;
 
 pub mod imports {
     pub mod import_assets;

crates/ide-db/src/rename.rs

@@ -71,12 +71,29 @@ impl Definition {
         sema: &Semantics<'_, RootDatabase>,
         new_name: &str,
     ) -> Result<SourceChange> {
+        // self.krate() returns None if
+        // self is a built-in attr, built-in type or tool module.
+        // it is not allowed for these defs to be renamed.
+        // cases where self.krate() is None is handled below.
+        if let Some(krate) = self.krate(sema.db) {
+            if !krate.origin(sema.db).is_local() {
+                bail!("Cannot rename a non-local definition.")
+            }
+        }
+
         match *self {
             Definition::Module(module) => rename_mod(sema, module, new_name),
+            Definition::ToolModule(_) => {
+                bail!("Cannot rename a tool module")
+            }
             Definition::BuiltinType(_) => {
                 bail!("Cannot rename builtin type")
             }
+            Definition::BuiltinAttr(_) => {
+                bail!("Cannot rename a builtin attr.")
+            }
             Definition::SelfType(_) => bail!("Cannot rename `Self`"),
+            Definition::Macro(mac) => rename_reference(sema, Definition::Macro(mac), new_name),
             def => rename_reference(sema, def, new_name),
         }
     }

crates/ide-db/src/rust_doc.rs

@@ -1,5 +1,7 @@
 //! Rustdoc specific doc comment handling
 
+use crate::documentation::Documentation;
+
 // stripped down version of https://github.com/rust-lang/rust/blob/392ba2ba1a7d6c542d2459fb8133bebf62a4a423/src/librustdoc/html/markdown.rs#L810-L933
 pub fn is_rust_fence(s: &str) -> bool {
     let mut seen_rust_tags = false;
@@ -32,3 +34,170 @@ pub fn is_rust_fence(s: &str) -> bool {
 
     !seen_other_tags || seen_rust_tags
 }
+
+const RUSTDOC_FENCES: [&str; 2] = ["```", "~~~"];
+
+pub fn format_docs(src: &Documentation) -> String {
+    format_docs_(src.as_str())
+}
+
+fn format_docs_(src: &str) -> String {
+    let mut processed_lines = Vec::new();
+    let mut in_code_block = false;
+    let mut is_rust = false;
+
+    for mut line in src.lines() {
+        if in_code_block && is_rust && code_line_ignored_by_rustdoc(line) {
+            continue;
+        }
+
+        if let Some(header) = RUSTDOC_FENCES.into_iter().find_map(|fence| line.strip_prefix(fence))
+        {
+            in_code_block ^= true;
+
+            if in_code_block {
+                is_rust = is_rust_fence(header);
+
+                if is_rust {
+                    line = "```rust";
+                }
+            }
+        }
+
+        if in_code_block {
+            let trimmed = line.trim_start();
+            if is_rust && trimmed.starts_with("##") {
+                line = &trimmed[1..];
+            }
+        }
+
+        processed_lines.push(line);
+    }
+    processed_lines.join("\n")
+}
+
+fn code_line_ignored_by_rustdoc(line: &str) -> bool {
+    let trimmed = line.trim();
+    trimmed == "#" || trimmed.starts_with("# ") || trimmed.starts_with("#\t")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_format_docs_adds_rust() {
+        let comment = "```\nfn some_rust() {}\n```";
+        assert_eq!(format_docs_(comment), "```rust\nfn some_rust() {}\n```");
+    }
+
+    #[test]
+    fn test_format_docs_handles_plain_text() {
+        let comment = "```text\nthis is plain text\n```";
+        assert_eq!(format_docs_(comment), "```text\nthis is plain text\n```");
+    }
+
+    #[test]
+    fn test_format_docs_handles_non_rust() {
+        let comment = "```sh\nsupposedly shell code\n```";
+        assert_eq!(format_docs_(comment), "```sh\nsupposedly shell code\n```");
+    }
+
+    #[test]
+    fn test_format_docs_handles_rust_alias() {
+        let comment = "```ignore\nlet z = 55;\n```";
+        assert_eq!(format_docs_(comment), "```rust\nlet z = 55;\n```");
+    }
+
+    #[test]
+    fn test_format_docs_handles_complex_code_block_attrs() {
+        let comment = "```rust,no_run\nlet z = 55;\n```";
+        assert_eq!(format_docs_(comment), "```rust\nlet z = 55;\n```");
+    }
+
+    #[test]
+    fn test_format_docs_handles_error_codes() {
+        let comment = "```compile_fail,E0641\nlet b = 0 as *const _;\n```";
+        assert_eq!(format_docs_(comment), "```rust\nlet b = 0 as *const _;\n```");
+    }
+
+    #[test]
+    fn test_format_docs_skips_comments_in_rust_block() {
+        let comment =
+            "```rust\n # skip1\n# skip2\n#stay1\nstay2\n#\n #\n   #    \n #\tskip3\n\t#\t\n```";
+        assert_eq!(format_docs_(comment), "```rust\n#stay1\nstay2\n```");
+    }
+
+    #[test]
+    fn test_format_docs_does_not_skip_lines_if_plain_text() {
+        let comment =
+            "```text\n # stay1\n# stay2\n#stay3\nstay4\n#\n #\n   #    \n #\tstay5\n\t#\t\n```";
+        assert_eq!(
+            format_docs_(comment),
+            "```text\n # stay1\n# stay2\n#stay3\nstay4\n#\n #\n   #    \n #\tstay5\n\t#\t\n```",
+        );
+    }
+
+    #[test]
+    fn test_format_docs_keeps_comments_outside_of_rust_block() {
+        let comment = " # stay1\n# stay2\n#stay3\nstay4\n#\n #\n   #    \n #\tstay5\n\t#\t";
+        assert_eq!(format_docs_(comment), comment);
+    }
+
+    #[test]
+    fn test_format_docs_preserves_newlines() {
+        let comment = "this\nis\nmultiline";
+        assert_eq!(format_docs_(comment), comment);
+    }
+
+    #[test]
+    fn test_code_blocks_in_comments_marked_as_rust() {
+        let comment = r#"```rust
+fn main(){}
+```
+Some comment.
+```
+let a = 1;
+```"#;
+
+        assert_eq!(
+            format_docs_(comment),
+            "```rust\nfn main(){}\n```\nSome comment.\n```rust\nlet a = 1;\n```"
+        );
+    }
+
+    #[test]
+    fn test_code_blocks_in_comments_marked_as_text() {
+        let comment = r#"```text
+filler
+text
+```
+Some comment.
+```
+let a = 1;
+```"#;
+
+        assert_eq!(
+            format_docs_(comment),
+            "```text\nfiller\ntext\n```\nSome comment.\n```rust\nlet a = 1;\n```"
+        );
+    }
+
+    #[test]
+    fn test_format_docs_handles_escape_double_hashes() {
+        let comment = r#"```rust
+let s = "foo
+## bar # baz";
+```"#;
+
+        assert_eq!(format_docs_(comment), "```rust\nlet s = \"foo\n# bar # baz\";\n```");
+    }
+
+    #[test]
+    fn test_format_docs_handles_double_hashes_non_rust() {
+        let comment = r#"```markdown
+## A second-level heading
+```"#;
+        assert_eq!(format_docs_(comment), "```markdown\n## A second-level heading\n```");
+    }
+}

crates/ide-db/src/search.rs

@@ -6,7 +6,7 @@
 
 use std::mem;
 
-use base_db::{FileId, FileRange, SourceDatabase, SourceDatabaseExt};
+use base_db::{salsa::Database, FileId, FileRange, SourceDatabase, SourceDatabaseExt};
 use hir::{
     AsAssocItem, DefWithBody, HasAttrs, HasSource, InFile, ModuleSource, Semantics, Visibility,
 };
@@ -221,7 +221,6 @@ impl Definition {
         }
 
         // def is crate root
-        // FIXME: We don't do searches for crates currently, as a crate does not actually have a single name
         if let &Definition::Module(module) = self {
             if module.is_crate_root() {
                 return SearchScope::reverse_dependencies(db, module.krate());
@@ -393,7 +392,10 @@ impl<'a> FindUsages<'a> {
         let name = match self.def {
             // special case crate modules as these do not have a proper name
             Definition::Module(module) if module.is_crate_root() => {
-                // FIXME: This assumes the crate name is always equal to its display name when it really isn't
+                // FIXME: This assumes the crate name is always equal to its display name when it
+                // really isn't
+                // we should instead look at the dependency edge name and recursively search our way
+                // up the ancestors
                 module
                     .krate()
                     .display_name(self.sema.db)
@@ -468,6 +470,7 @@ impl<'a> FindUsages<'a> {
         };
 
         for (text, file_id, search_range) in scope_files(sema, &search_scope) {
+            self.sema.db.unwind_if_cancelled();
             let tree = Lazy::new(move || sema.parse(file_id).syntax().clone());
 
             // Search for occurrences of the items name
@@ -504,6 +507,7 @@ impl<'a> FindUsages<'a> {
             let finder = &Finder::new("super");
 
             for (text, file_id, search_range) in scope_files(sema, &scope) {
+                self.sema.db.unwind_if_cancelled();
                 let tree = Lazy::new(move || sema.parse(file_id).syntax().clone());
 
                 for offset in match_indices(&text, finder, search_range) {

crates/ide-db/src/syntax_helpers/format_string.rs

@@ -1,10 +1,10 @@
 //! Tools to work with format string literals for the `format_args!` family of macros.
-use crate::syntax_helpers::node_ext::macro_call_for_string_token;
 use syntax::{
     ast::{self, IsString},
-    TextRange, TextSize,
+    AstNode, AstToken, TextRange, TextSize,
 };
 
+// FIXME: This can probably be re-implemented via the HIR?
 pub fn is_format_string(string: &ast::String) -> bool {
     // Check if `string` is a format string argument of a macro invocation.
     // `string` is a string literal, mapped down into the innermost macro expansion.
@@ -15,19 +15,9 @@ pub fn is_format_string(string: &ast::String) -> bool {
     // This setup lets us correctly highlight the components of `concat!("{}", "bla")` format
     // strings. It still fails for `concat!("{", "}")`, but that is rare.
     (|| {
-        let name = macro_call_for_string_token(string)?.path()?.segment()?.name_ref()?;
+        let lit = string.syntax().parent().and_then(ast::Literal::cast)?;
-
+        let fa = lit.syntax().parent().and_then(ast::FormatArgsExpr::cast)?;
-        if !matches!(
+        (fa.template()? == ast::Expr::Literal(lit)).then_some(|| ())
-            name.text().as_str(),
-            "format_args" | "format_args_nl" | "const_format_args" | "panic_2015" | "panic_2021"
-        ) {
-            return None;
-        }
-
-        // NB: we match against `panic_2015`/`panic_2021` here because they have a special-cased arm for
-        // `"{}"`, which otherwise wouldn't get highlighted.
-
-        Some(())
     })()
     .is_some()
 }

crates/ide-db/src/syntax_helpers/node_ext.rs

@@ -312,7 +312,6 @@ pub fn for_each_tail_expr(expr: &ast::Expr, cb: &mut dyn FnMut(&ast::Expr)) {
         ast::Expr::ArrayExpr(_)
         | ast::Expr::AwaitExpr(_)
         | ast::Expr::BinExpr(_)
-        | ast::Expr::BoxExpr(_)
         | ast::Expr::BreakExpr(_)
         | ast::Expr::CallExpr(_)
         | ast::Expr::CastExpr(_)
@@ -335,7 +334,10 @@ pub fn for_each_tail_expr(expr: &ast::Expr, cb: &mut dyn FnMut(&ast::Expr)) {
         | ast::Expr::LetExpr(_)
         | ast::Expr::UnderscoreExpr(_)
         | ast::Expr::YieldExpr(_)
-        | ast::Expr::YeetExpr(_) => cb(expr),
+        | ast::Expr::YeetExpr(_)
+        | ast::Expr::OffsetOfExpr(_)
+        | ast::Expr::FormatArgsExpr(_)
+        | ast::Expr::AsmExpr(_) => cb(expr),
     }
 }
 

crates/ide-diagnostics/src/handlers/macro_error.rs

@@ -157,6 +157,7 @@ struct S;
     fn macro_diag_builtin() {
         check_diagnostics(
             r#"
+//- minicore: fmt
 #[rustc_builtin_macro]
 macro_rules! env {}
 
@@ -166,9 +167,6 @@ macro_rules! include {}
 #[rustc_builtin_macro]
 macro_rules! compile_error {}
 
-#[rustc_builtin_macro]
-macro_rules! format_args { () => {} }
-
 fn main() {
     // Test a handful of built-in (eager) macros:
 
@@ -189,7 +187,7 @@ fn main() {
     // Lazy:
 
     format_args!();
-  //^^^^^^^^^^^ error: no rule matches input tokens
+  //^^^^^^^^^^^ error: Syntax Error in Expansion: expected expression
 }
 "#,
         );

crates/ide-diagnostics/src/handlers/mismatched_arg_count.rs

@@ -1,10 +1,37 @@
+use either::Either;
+use hir::InFile;
 use syntax::{
     ast::{self, HasArgList},
-    AstNode, TextRange,
+    AstNode, SyntaxNodePtr, TextRange,
 };
 
 use crate::{adjusted_display_range, Diagnostic, DiagnosticCode, DiagnosticsContext};
 
+// Diagnostic: mismatched-tuple-struct-pat-arg-count
+//
+// This diagnostic is triggered if a function is invoked with an incorrect amount of arguments.
+pub(crate) fn mismatched_tuple_struct_pat_arg_count(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::MismatchedTupleStructPatArgCount,
+) -> Diagnostic {
+    let s = if d.found == 1 { "" } else { "s" };
+    let s2 = if d.expected == 1 { "" } else { "s" };
+    let message = format!(
+        "this pattern has {} field{s}, but the corresponding tuple struct has {} field{s2}",
+        d.found, d.expected
+    );
+    Diagnostic::new(
+        DiagnosticCode::RustcHardError("E0023"),
+        message,
+        invalid_args_range(
+            ctx,
+            d.expr_or_pat.clone().map(|it| it.either(Into::into, Into::into)),
+            d.expected,
+            d.found,
+        ),
+    )
+}
+
 // Diagnostic: mismatched-arg-count
 //
 // This diagnostic is triggered if a function is invoked with an incorrect amount of arguments.
@@ -14,31 +41,63 @@ pub(crate) fn mismatched_arg_count(
 ) -> Diagnostic {
     let s = if d.expected == 1 { "" } else { "s" };
     let message = format!("expected {} argument{s}, found {}", d.expected, d.found);
-    Diagnostic::new(DiagnosticCode::RustcHardError("E0107"), message, invalid_args_range(ctx, d))
+    Diagnostic::new(
+        DiagnosticCode::RustcHardError("E0107"),
+        message,
+        invalid_args_range(ctx, d.call_expr.clone().map(Into::into), d.expected, d.found),
+    )
 }
 
-fn invalid_args_range(ctx: &DiagnosticsContext<'_>, d: &hir::MismatchedArgCount) -> TextRange {
+fn invalid_args_range(
-    adjusted_display_range::<ast::Expr>(ctx, d.call_expr.clone().map(|it| it.into()), &|expr| {
+    ctx: &DiagnosticsContext<'_>,
-        let arg_list = match expr {
+    source: InFile<SyntaxNodePtr>,
-            ast::Expr::CallExpr(call) => call.arg_list()?,
+    expected: usize,
-            ast::Expr::MethodCallExpr(call) => call.arg_list()?,
+    found: usize,
+) -> TextRange {
+    adjusted_display_range::<Either<ast::Expr, ast::TupleStructPat>>(ctx, source, &|expr| {
+        let (text_range, r_paren_token, expected_arg) = match expr {
+            Either::Left(ast::Expr::CallExpr(call)) => {
+                let arg_list = call.arg_list()?;
+                (
+                    arg_list.syntax().text_range(),
+                    arg_list.r_paren_token(),
+                    arg_list.args().nth(expected).map(|it| it.syntax().text_range()),
+                )
+            }
+            Either::Left(ast::Expr::MethodCallExpr(call)) => {
+                let arg_list = call.arg_list()?;
+                (
+                    arg_list.syntax().text_range(),
+                    arg_list.r_paren_token(),
+                    arg_list.args().nth(expected).map(|it| it.syntax().text_range()),
+                )
+            }
+            Either::Right(pat) => {
+                let r_paren = pat.r_paren_token()?;
+                let l_paren = pat.l_paren_token()?;
+                (
+                    l_paren.text_range().cover(r_paren.text_range()),
+                    Some(r_paren),
+                    pat.fields().nth(expected).map(|it| it.syntax().text_range()),
+                )
+            }
             _ => return None,
         };
-        if d.found < d.expected {
+        if found < expected {
-            if d.found == 0 {
+            if found == 0 {
-                return Some(arg_list.syntax().text_range());
+                return Some(text_range);
             }
-            if let Some(r_paren) = arg_list.r_paren_token() {
+            if let Some(r_paren) = r_paren_token {
                 return Some(r_paren.text_range());
             }
         }
-        if d.expected < d.found {
+        if expected < found {
-            if d.expected == 0 {
+            if expected == 0 {
-                return Some(arg_list.syntax().text_range());
+                return Some(text_range);
             }
-            let zip = arg_list.args().nth(d.expected).zip(arg_list.r_paren_token());
+            let zip = expected_arg.zip(r_paren_token);
             if let Some((arg, r_paren)) = zip {
-                return Some(arg.syntax().text_range().cover(r_paren.text_range()));
+                return Some(arg.cover(r_paren.text_range()));
             }
         }
 
@@ -331,4 +390,21 @@ fn g() {
             "#,
         )
     }
+
+    #[test]
+    fn tuple_struct_pat() {
+        check_diagnostics(
+            r#"
+struct S(u32, u32);
+fn f(
+    S(a, b, c): S,
+         // ^^ error: this pattern has 3 fields, but the corresponding tuple struct has 2 fields
+    S(): S,
+  // ^^ error: this pattern has 0 fields, but the corresponding tuple struct has 2 fields
+    S(e, f, .., g, d): S
+  //        ^^^^^^^^^ error: this pattern has 4 fields, but the corresponding tuple struct has 2 fields
+) {}
+"#,
+        )
+    }
 }

crates/ide-diagnostics/src/handlers/missing_match_arms.rs

@@ -319,6 +319,7 @@ fn main() {
     match Either::A {
         Either::A => (),
         Either::B() => (),
+              // ^^ error: this pattern has 0 fields, but the corresponding tuple struct has 1 field
     }
 }
 "#,
@@ -334,9 +335,11 @@ enum A { B(isize, isize), C }
 fn main() {
     match A::B(1, 2) {
         A::B(_, _, _) => (),
+                // ^^ error: this pattern has 3 fields, but the corresponding tuple struct has 2 fields
     }
     match A::B(1, 2) {
         A::C(_) => (),
+         // ^^^ error: this pattern has 1 field, but the corresponding tuple struct has 0 fields
     }
 }
 "#,
@@ -846,6 +849,7 @@ fn main() {
 struct Foo { }
 fn main(f: Foo) {
     match f { Foo { bar } => () }
+                 // ^^^ error: no such field
 }
 "#,
         );