feature: move linked_projects discovery to the rust-analyzer server

Cargo.lock

@@ -4,9 +4,9 @@ version = 3
 
 [[package]]
 name = "addr2line"
-version = "0.21.0"
+version = "0.22.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a30b2e23b9e17a9f90641c7ab1549cd9b44f296d3ccbf309d2863cfe398a0cb"
+checksum = "6e4503c46a5c0c7844e948c9a4d6acd9f50cccb4de1c48eb9e291ea17470c678"
 dependencies = [
  "gimli",
 ]
@@ -28,9 +28,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.83"
+version = "1.0.86"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "25bdb32cbbdce2b519a9cd7df3a678443100e265d5e25ca763b7572a5104f5f3"
+checksum = "b3d1d046238990b9cf5bcde22a3fb3584ee5cf65fb2765f454ed428c7a0063da"
 
 [[package]]
 name = "arbitrary"
@@ -52,16 +52,16 @@ checksum = "0c4b4d0bd25bd0b74681c0ad21497610ce1b7c91b1022cd21c80c6fbdd9476b0"
 
 [[package]]
 name = "backtrace"
-version = "0.3.71"
+version = "0.3.72"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "26b05800d2e817c8b3b4b54abd461726265fa9789ae34330622f2db9ee696f9d"
+checksum = "17c6a35df3749d2e8bb1b7b21a976d82b15548788d2735b9d82f329268f71a11"
 dependencies = [
  "addr2line",
  "cc",
  "cfg-if",
  "libc",
  "miniz_oxide",
- "object 0.32.2",
+ "object 0.35.0",
  "rustc-demangle",
 ]
 
@@ -104,9 +104,9 @@ checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
 
 [[package]]
 name = "camino"
-version = "1.1.6"
+version = "1.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c59e92b5a388f549b863a7bea62612c09f24c8393560709a54558a9abdfb3b9c"
+checksum = "e0ec6b951b160caa93cc0c7b209e5a3bff7aae9062213451ac99493cd844c239"
 dependencies = [
  "serde",
 ]
@@ -136,9 +136,9 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.0.97"
+version = "1.0.98"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "099a5357d84c4c61eb35fc8eafa9a79a902c2f76911e5747ced4e032edd8d9b4"
+checksum = "41c270e7540d725e65ac7f1b212ac8ce349719624d7bcff99f8e2e488e8cf03f"
 
 [[package]]
 name = "cfg"
@@ -232,18 +232,18 @@ checksum = "0d48d8f76bd9331f19fe2aaf3821a9f9fb32c3963e1e3d6ce82a8c09cef7444a"
 
 [[package]]
 name = "crc32fast"
-version = "1.4.0"
+version = "1.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b3855a8a784b474f333699ef2bbca9db2c4a1f6d9088a90a2d25b1eb53111eaa"
+checksum = "a97769d94ddab943e4510d138150169a2758b5ef3eb191a9ee688de3e23ef7b3"
 dependencies = [
  "cfg-if",
 ]
 
 [[package]]
 name = "crossbeam-channel"
-version = "0.5.12"
+version = "0.5.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ab3db02a9c5b5121e1e42fbdb1aeb65f5e02624cc58c43f2884c6ccac0b82f95"
+checksum = "33480d6946193aa8033910124896ca395333cae7e2d1113d1fef6c3272217df2"
 dependencies = [
  "crossbeam-utils",
 ]
@@ -269,9 +269,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.19"
+version = "0.8.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "248e3bacc7dc6baa3b21e405ee045c3047101a49145e7e9eca583ab4c2ca5345"
+checksum = "22ec99545bb0ed0ea7bb9b8e1e9122ea386ff8a48c0922e43f36d45ab09e0e80"
 
 [[package]]
 name = "ctrlc"
@@ -366,9 +366,9 @@ checksum = "9bda8e21c04aca2ae33ffc2fd8c23134f3cac46db123ba97bd9d3f3b8a4a85e1"
 
 [[package]]
 name = "either"
-version = "1.11.0"
+version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a47c1c47d2f5964e29c61246e81db715514cd532db6b5116a25ea3c03d6780a2"
+checksum = "3dca9240753cf90908d7e4aac30f630662b02aebaa1b58a3cadabdb23385b58b"
 
 [[package]]
 name = "ena"
@@ -431,6 +431,7 @@ dependencies = [
  "crossbeam-channel",
  "paths",
  "process-wrap",
+ "project-model",
  "rustc-hash",
  "serde",
  "serde_json",
@@ -476,9 +477,9 @@ dependencies = [
 
 [[package]]
 name = "gimli"
-version = "0.28.1"
+version = "0.29.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4271d37baee1b8c7e4b708028c57d816cf9d2434acb33a549475f78c181f6253"
+checksum = "40ecd4077b5ae9fd2e9e169b102c6c330d0605168eb0e8bf79952b256dbefffd"
 
 [[package]]
 name = "hashbrown"
@@ -916,9 +917,9 @@ dependencies = [
 
 [[package]]
 name = "libmimalloc-sys"
-version = "0.1.37"
+version = "0.1.38"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "81eb4061c0582dedea1cbc7aff2240300dd6982e0239d1c99e65c1dbf4a30ba7"
+checksum = "0e7bb23d733dfcc8af652a78b7bf232f0e967710d044732185e561e47c0336b6"
 dependencies = [
  "cc",
  "libc",
@@ -1086,18 +1087,18 @@ dependencies = [
 
 [[package]]
 name = "mimalloc"
-version = "0.1.41"
+version = "0.1.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9f41a2280ded0da56c8cf898babb86e8f10651a34adcfff190ae9a1159c6908d"
+checksum = "e9186d86b79b52f4a77af65604b51225e8db1d6ee7e3f41aec1e40829c71a176"
 dependencies = [
  "libmimalloc-sys",
 ]
 
 [[package]]
 name = "miniz_oxide"
-version = "0.7.2"
+version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9d811f3e15f28568be3407c8e7fdb6514c1cda3cb30683f15b6a1a1dc4ea14a7"
+checksum = "87dfd01fe195c66b572b37921ad8803d010623c0aca821bea2302239d155cdae"
 dependencies = [
  "adler",
 ]
@@ -1162,9 +1163,9 @@ dependencies = [
 
 [[package]]
 name = "nu-ansi-term"
-version = "0.49.0"
+version = "0.50.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c073d3c1930d0751774acf49e66653acecb416c3a54c6ec095a9b11caddb5a68"
+checksum = "dd2800e1520bdc966782168a627aa5d1ad92e33b984bf7c7615d31280c83ff14"
 dependencies = [
  "windows-sys 0.48.0",
 ]
@@ -1187,18 +1188,18 @@ dependencies = [
 
 [[package]]
 name = "object"
-version = "0.32.2"
+version = "0.33.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a6a622008b6e321afc04970976f62ee297fdbaa6f95318ca343e3eebb9648441"
+checksum = "d8dd6c0cdf9429bce006e1362bfce61fa1bfd8c898a643ed8d2b471934701d3d"
 dependencies = [
  "memchr",
 ]
 
 [[package]]
 name = "object"
-version = "0.33.0"
+version = "0.35.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d8dd6c0cdf9429bce006e1362bfce61fa1bfd8c898a643ed8d2b471934701d3d"
+checksum = "b8ec7ab813848ba4522158d5517a6093db1ded27575b070f4177b8d12b41db5e"
 dependencies = [
  "memchr",
 ]
@@ -1223,9 +1224,9 @@ checksum = "04744f49eae99ab78e0d5c0b603ab218f515ea8cfe5a456d7629ad883a3b6e7d"
 
 [[package]]
 name = "parking_lot"
-version = "0.12.2"
+version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e4af0ca4f6caed20e900d564c242b8e5d4903fdacf31d3daf527b66fe6f42fb"
+checksum = "f1bf18183cf54e8d6059647fc3063646a1801cf30896933ec2311622cc4b9a27"
 dependencies = [
  "lock_api",
  "parking_lot_core",
@@ -1379,9 +1380,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.82"
+version = "1.0.85"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8ad3d49ab951a01fbaafe34f2ec74122942fe18a3f9814c3268f1bb72042131b"
+checksum = "22244ce15aa966053a896d1accb3a6e68469b97c7f33f284b99f0d576879fc23"
 dependencies = [
  "unicode-ident",
 ]
@@ -1800,18 +1801,18 @@ dependencies = [
 
 [[package]]
 name = "serde"
-version = "1.0.201"
+version = "1.0.203"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "780f1cebed1629e4753a1a38a3c72d30b97ec044f0aef68cb26650a3c5cf363c"
+checksum = "7253ab4de971e72fb7be983802300c30b5a7f0c2e56fab8abfc6a214307c0094"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.201"
+version = "1.0.203"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c5e405930b9796f1c00bee880d03fc7e0bb4b9a11afc776885ffe84320da2865"
+checksum = "500cbc0ebeb6f46627f50f3f5811ccf6bf00643be300b4c3eabc0ef55dc5b5ba"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1843,9 +1844,9 @@ dependencies = [
 
 [[package]]
 name = "serde_spanned"
-version = "0.6.5"
+version = "0.6.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eb3622f419d1296904700073ea6cc23ad690adbd66f13ea683df73298736f0c1"
+checksum = "79e674e01f999af37c49f70a6ede167a8a60b2503e56c5599532a65baa5969a0"
 dependencies = [
  "serde",
 ]
@@ -1867,9 +1868,9 @@ checksum = "3c5e1a9a646d36c3599cd173a41282daf47c44583ad367b8e6837255952e5c67"
 
 [[package]]
 name = "smol_str"
-version = "0.2.1"
+version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6845563ada680337a52d43bb0b29f396f2d911616f6573012645b9e3d048a49"
+checksum = "dd538fb6910ac1099850255cf94a94df6551fbdd602454387d0adb2d1ca6dead"
 dependencies = [
  "serde",
 ]
@@ -1922,9 +1923,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.63"
+version = "2.0.66"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf5be731623ca1a1fb7d8be6f261a3be6d3e2337b8a1f97be944d020c8fcb704"
+checksum = "c42f3f41a2de00b01c0aaad383c5a45241efc8b2d1eda5661812fda5f3cdcff5"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2009,18 +2010,18 @@ checksum = "f18aa187839b2bdb1ad2fa35ead8c4c2976b64e4363c386d45ac0f7ee85c9233"
 
 [[package]]
 name = "thiserror"
-version = "1.0.60"
+version = "1.0.61"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "579e9083ca58dd9dcf91a9923bb9054071b9ebbd800b342194c9feb0ee89fc18"
+checksum = "c546c80d6be4bc6a00c0f01730c08df82eaa7a7a61f11d656526506112cc1709"
 dependencies = [
  "thiserror-impl",
 ]
 
 [[package]]
 name = "thiserror-impl"
-version = "1.0.60"
+version = "1.0.61"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e2470041c06ec3ac1ab38d0356a6119054dedaea53e12fbefc0de730a1c08524"
+checksum = "46c3384250002a6d5af4d114f2845d37b57521033f30d5c3f46c4d70e1197533"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2104,9 +2105,9 @@ checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"
 
 [[package]]
 name = "toml"
-version = "0.8.12"
+version = "0.8.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e9dd1545e8208b4a5af1aa9bbd0b4cf7e9ea08fabc5d0a5c67fcaafa17433aa3"
+checksum = "6f49eb2ab21d2f26bd6db7bf383edc527a7ebaee412d17af4d40fdccd442f335"
 dependencies = [
  "serde",
  "serde_spanned",
@@ -2116,18 +2117,18 @@ dependencies = [
 
 [[package]]
 name = "toml_datetime"
-version = "0.6.5"
+version = "0.6.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3550f4e9685620ac18a50ed434eb3aec30db8ba93b0287467bca5826ea25baf1"
+checksum = "4badfd56924ae69bcc9039335b2e017639ce3f9b001c393c1b2d1ef846ce2cbf"
 dependencies = [
  "serde",
 ]
 
 [[package]]
 name = "toml_edit"
-version = "0.22.12"
+version = "0.22.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d3328d4f68a705b2a4498da1d580585d39a6510f98318a2cec3018a7ec61ddef"
+checksum = "f21c7aaf97f1bd9ca9d4f9e73b0a6c74bd5afef56f2bc931943a6e1c37e04e38"
 dependencies = [
  "indexmap",
  "serde",
@@ -2201,9 +2202,9 @@ dependencies = [
 
 [[package]]
 name = "tracing-tree"
-version = "0.3.0"
+version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "65139ecd2c3f6484c3b99bc01c77afe21e95473630747c7aca525e78b0666675"
+checksum = "b56c62d2c80033cb36fae448730a2f2ef99410fe3ecbffc916681a32f6807dbe"
 dependencies = [
  "nu-ansi-term",
  "tracing-core",
@@ -2213,9 +2214,9 @@ dependencies = [
 
 [[package]]
 name = "triomphe"
-version = "0.1.11"
+version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "859eb650cfee7434994602c3a68b25d77ad9e68c8a6cd491616ef86661382eb3"
+checksum = "1b2cb4fbb9995eeb36ac86fadf24031ccd58f99d6b4b2d7b911db70bddb80d90"
 dependencies = [
  "serde",
  "stable_deref_trait",
@@ -2555,9 +2556,9 @@ checksum = "bec47e5bfd1bff0eeaf6d8b485cc1074891a197ab4225d504cb7a1ab88b02bf0"
 
 [[package]]
 name = "winnow"
-version = "0.6.8"
+version = "0.6.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c3c52e9c97a68071b23e836c9380edae937f17b9c4667bd021973efc689f618d"
+checksum = "56c52728401e1dc672a56e81e593e912aa54c78f40246869f78359a2bf24d29d"
 dependencies = [
  "memchr",
 ]

crates/flycheck/Cargo.toml

@@ -24,6 +24,7 @@ process-wrap.workspace = true
 paths.workspace = true
 stdx.workspace = true
 toolchain.workspace = true
+project-model.workspace = true
 
 [lints]
 workspace = true

crates/flycheck/src/lib.rs

@@ -20,6 +20,7 @@ pub use cargo_metadata::diagnostic::{
 use toolchain::Tool;
 
 mod command;
+pub mod project_json;
 mod test_runner;
 
 use command::{CommandHandle, ParseFromLine};
@@ -240,7 +241,7 @@ enum FlycheckStatus {
     Finished,
 }
 
-const SAVED_FILE_PLACEHOLDER: &str = "$saved_file";
+pub const SAVED_FILE_PLACEHOLDER: &str = "$saved_file";
 
 impl FlycheckActor {
     fn new(

crates/flycheck/src/project_json.rs

@@ -0,0 +1,152 @@
+//! A `cargo-metadata`-equivalent for non-Cargo build systems.
+use std::{io, process::Command};
+
+use crossbeam_channel::Sender;
+use paths::{AbsPathBuf, Utf8Path, Utf8PathBuf};
+use project_model::ProjectJsonData;
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+use crate::command::{CommandHandle, ParseFromLine};
+
+pub const ARG_PLACEHOLDER: &str = "{arg}";
+
+/// A command wrapper for getting a `rust-project.json`.
+///
+/// This is analogous to `cargo-metadata`, but for non-Cargo build systems.
+pub struct Discover {
+    command: Vec<String>,
+    sender: Sender<DiscoverProjectMessage>,
+}
+
+#[derive(PartialEq, Clone, Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub enum DiscoverArgument {
+    Path(#[serde(serialize_with = "serialize_abs_pathbuf")] AbsPathBuf),
+    Buildfile(#[serde(serialize_with = "serialize_abs_pathbuf")] AbsPathBuf),
+}
+
+fn serialize_abs_pathbuf<S>(path: &AbsPathBuf, se: S) -> Result<S::Ok, S::Error>
+where
+    S: serde::Serializer,
+{
+    let path: &Utf8Path = path.as_ref();
+    se.serialize_str(path.as_str())
+}
+
+impl Discover {
+    /// Create a new [Discover].
+    pub fn new(sender: Sender<DiscoverProjectMessage>, command: Vec<String>) -> Self {
+        Self { sender, command }
+    }
+
+    /// Spawn the command inside [Discover] and report progress, if any.
+    pub fn spawn(&self, discover_arg: DiscoverArgument) -> io::Result<DiscoverHandle> {
+        let command = &self.command[0];
+        let args = &self.command[1..];
+
+        let args: Vec<String> = args
+            .iter()
+            .map(|arg| {
+                if arg == ARG_PLACEHOLDER {
+                    serde_json::to_string(&discover_arg).expect("Unable to serialize args")
+                } else {
+                    arg.to_owned()
+                }
+            })
+            .collect();
+
+        let mut cmd = Command::new(command);
+        cmd.args(args);
+
+        Ok(DiscoverHandle { _handle: CommandHandle::spawn(cmd, self.sender.clone())? })
+    }
+}
+
+/// A handle to a spawned [Discover].
+#[derive(Debug)]
+pub struct DiscoverHandle {
+    _handle: CommandHandle<DiscoverProjectMessage>,
+}
+
+/// An enum containing either progress messages, an error,
+/// or the materialized `rust-project`.
+#[derive(Debug, Clone, Deserialize, Serialize)]
+#[serde(tag = "kind")]
+#[serde(rename_all = "snake_case")]
+enum DiscoverProjectData {
+    Finished { buildfile: Utf8PathBuf, project: ProjectJsonData },
+    Error { error: String, source: Option<String> },
+    Progress { message: String },
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum DiscoverProjectMessage {
+    Finished { project: ProjectJsonData, buildfile: AbsPathBuf },
+    Error { error: String, source: Option<String> },
+    Progress { message: String },
+}
+
+impl DiscoverProjectMessage {
+    fn new(data: DiscoverProjectData) -> Self {
+        match data {
+            DiscoverProjectData::Finished { project, buildfile, .. } => {
+                let buildfile = buildfile.try_into().expect("Unable to make path absolute");
+                DiscoverProjectMessage::Finished { project, buildfile }
+            }
+            DiscoverProjectData::Error { error, source } => {
+                DiscoverProjectMessage::Error { error, source }
+            }
+            DiscoverProjectData::Progress { message } => {
+                DiscoverProjectMessage::Progress { message }
+            }
+        }
+    }
+}
+
+impl ParseFromLine for DiscoverProjectMessage {
+    fn from_line(line: &str, _error: &mut String) -> Option<Self> {
+        // can the line even be deserialized as JSON?
+        let Ok(data) = serde_json::from_str::<Value>(line) else {
+            let err = DiscoverProjectData::Error { error: line.to_owned(), source: None };
+            return Some(DiscoverProjectMessage::new(err));
+        };
+
+        let Ok(data) = serde_json::from_value::<DiscoverProjectData>(data) else {
+            return None;
+        };
+
+        let msg = DiscoverProjectMessage::new(data);
+        Some(msg)
+    }
+
+    fn from_eof() -> Option<Self> {
+        None
+    }
+}
+
+#[test]
+fn test_deserialization() {
+    let message = r#"
+    {"kind": "progress", "message":"querying build system","input":{"files":["src/main.rs"]}}
+    "#;
+    let message: DiscoverProjectData =
+        serde_json::from_str(message).expect("Unable to deserialize message");
+    assert!(matches!(message, DiscoverProjectData::Progress { .. }));
+
+    let message = r#"
+    {"kind": "error", "error":"failed to deserialize command output","source":"command"}
+    "#;
+
+    let message: DiscoverProjectData =
+        serde_json::from_str(message).expect("Unable to deserialize message");
+    assert!(matches!(message, DiscoverProjectData::Error { .. }));
+
+    let message = r#"
+    {"kind": "finished", "project": {"sysroot": "foo", "crates": [], "runnables": []}, "buildfile":"rust-analyzer/BUILD"}
+    "#;
+
+    let message: DiscoverProjectData =
+        serde_json::from_str(message).expect("Unable to deserialize message");
+    assert!(matches!(message, DiscoverProjectData::Finished { .. }));
+}

crates/load-cargo/src/lib.rs

@@ -17,7 +17,6 @@ use itertools::Itertools;
 use proc_macro_api::{MacroDylib, ProcMacroServer};
 use project_model::{CargoConfig, ManifestPath, PackageRoot, ProjectManifest, ProjectWorkspace};
 use span::Span;
-use tracing::instrument;
 use vfs::{file_set::FileSetConfig, loader::Handle, AbsPath, AbsPathBuf, VfsPath};
 
 pub struct LoadCargoConfig {
@@ -51,7 +50,6 @@ pub fn load_workspace_at(
     load_workspace(workspace, &cargo_config.extra_env, load_config)
 }
 
-#[instrument(skip_all)]
 pub fn load_workspace(
     ws: ProjectWorkspace,
     extra_env: &FxHashMap<String, String>,

crates/project-model/src/project_json.rs

@@ -276,6 +276,16 @@ impl ProjectJson {
         self.manifest.as_ref()
     }
 
+    pub fn crate_by_buildfile(&self, path: &AbsPath) -> Option<Build> {
+        // this is fast enough for now, but it's unfortunate that this is O(crates).
+        let path: &std::path::Path = path.as_ref();
+        self.crates
+            .iter()
+            .filter(|krate| krate.is_workspace_member)
+            .filter_map(|krate| krate.build.clone())
+            .find(|build| build.build_file.as_std_path() == path)
+    }
+
     /// Returns the path to the project's manifest or root folder, if no manifest exists.
     pub fn manifest_or_root(&self) -> &AbsPath {
         self.manifest.as_ref().map_or(&self.project_root, |manifest| manifest.as_ref())
@@ -286,7 +296,7 @@ impl ProjectJson {
     }
 }
 
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[derive(Serialize, Deserialize, Debug, Clone, Eq, PartialEq)]
 pub struct ProjectJsonData {
     sysroot: Option<Utf8PathBuf>,
     sysroot_src: Option<Utf8PathBuf>,
@@ -295,7 +305,7 @@ pub struct ProjectJsonData {
     runnables: Vec<RunnableData>,
 }
 
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[derive(Serialize, Deserialize, Debug, Clone, Eq, PartialEq)]
 struct CrateData {
     display_name: Option<String>,
     root_module: Utf8PathBuf,
@@ -319,7 +329,7 @@ struct CrateData {
     build: Option<BuildData>,
 }
 
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[derive(Serialize, Deserialize, Debug, Clone, Eq, PartialEq)]
 #[serde(rename = "edition")]
 enum EditionData {
     #[serde(rename = "2015")]
@@ -332,7 +342,7 @@ enum EditionData {
     Edition2024,
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq)]
 pub struct BuildData {
     label: String,
     build_file: Utf8PathBuf,
@@ -419,7 +429,7 @@ pub(crate) struct Dep {
     pub(crate) name: CrateName,
 }
 
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
 struct CrateSource {
     include_dirs: Vec<Utf8PathBuf>,
     exclude_dirs: Vec<Utf8PathBuf>,

crates/project-model/src/workspace.rs

@@ -31,6 +31,7 @@ use crate::{
     utf8_stdout, CargoConfig, CargoWorkspace, InvocationStrategy, ManifestPath, Package,
     ProjectJson, ProjectManifest, Sysroot, TargetData, TargetKind, WorkspaceBuildScripts,
 };
+use tracing::{debug, error, info};
 
 pub type FileLoader<'a> = &'a mut dyn for<'b> FnMut(&'b AbsPath) -> Option<FileId>;
 
@@ -250,7 +251,7 @@ impl ProjectWorkspace {
                 };
 
                 let rustc =  rustc_dir.and_then(|rustc_dir| {
-                    tracing::info!(workspace = %cargo_toml, rustc_dir = %rustc_dir, "Using rustc source");
+                    info!(workspace = %cargo_toml, rustc_dir = %rustc_dir, "Using rustc source");
                     match CargoWorkspace::fetch_metadata(
                         &rustc_dir,
                         cargo_toml.parent(),
@@ -767,9 +768,9 @@ impl ProjectWorkspace {
         };
 
         if matches!(sysroot.mode(), SysrootMode::Stitched(_)) && crate_graph.patch_cfg_if() {
-            tracing::debug!("Patched std to depend on cfg-if")
+            debug!("Patched std to depend on cfg-if")
         } else {
-            tracing::debug!("Did not patch std to depend on cfg-if")
+            debug!("Did not patch std to depend on cfg-if")
         }
         (crate_graph, proc_macros)
     }
@@ -917,6 +918,11 @@ fn project_json_to_crate_graph(
                         CrateOrigin::Local { repo: None, name: None }
                     },
                 );
+                debug!(
+                    ?crate_graph_crate_id,
+                    crate = display_name.as_ref().map(|name| name.canonical_name().as_str()),
+                    "added root to crate graph"
+                );
                 if *is_proc_macro {
                     if let Some(path) = proc_macro_dylib_path.clone() {
                         let node = Ok((
@@ -931,6 +937,7 @@ fn project_json_to_crate_graph(
         )
         .collect();
 
+    debug!(map = ?idx_to_crate_id);
     for (from_idx, krate) in project.crates() {
         if let Some(&from) = idx_to_crate_id.get(&from_idx) {
             public_deps.add_to_crate_graph(crate_graph, from);
@@ -1156,7 +1163,7 @@ fn detached_file_to_crate_graph(
     let file_id = match load(detached_file) {
         Some(file_id) => file_id,
         None => {
-            tracing::error!("Failed to load detached file {:?}", detached_file);
+            error!("Failed to load detached file {:?}", detached_file);
             return (crate_graph, FxHashMap::default());
         }
     };
@@ -1351,7 +1358,7 @@ fn add_target_crate_root(
     crate_id
 }
 
-#[derive(Default)]
+#[derive(Default, Debug)]
 struct SysrootPublicDeps {
     deps: Vec<(CrateName, CrateId, bool)>,
 }

crates/rust-analyzer/src/bin/main.rs

@@ -175,6 +175,7 @@ fn run_server() -> anyhow::Result<()> {
             return Err(e.into());
         }
     };
+
     tracing::info!("InitializeParams: {}", initialize_params);
     let lsp_types::InitializeParams {
         root_uri,
@@ -264,7 +265,10 @@ fn run_server() -> anyhow::Result<()> {
         return Err(e.into());
     }
 
-    if !config.has_linked_projects() && config.detached_files().is_empty() {
+    if config.discover_workspace_config().is_none()
+        && !config.has_linked_projects()
+        && config.detached_files().is_empty()
+    {
         config.rediscover_workspaces();
     }
 

crates/rust-analyzer/src/config.rs

@@ -328,6 +328,102 @@ config_data! {
         /// `textDocument/rangeFormatting` request. The rustfmt option is unstable and only
         /// available on a nightly build.
         rustfmt_rangeFormatting_enable: bool = false,
+
+        /// Enables automatic discovery of projects using [`DiscoverWorkspaceConfig::command`].
+        ///
+        /// [`DiscoverWorkspaceConfig`] also requires setting `progress_label` and `files_to_watch`.
+        /// `progress_label` is used for the title in progress indicators, whereas `files_to_watch`
+        /// is used to determine which build system-specific files should be watched in order to
+        /// reload rust-analyzer.
+        ///
+        /// Below is an example of a valid configuration:
+        /// ```json
+        /// "rust-analyzer.workspace.discoverConfig": {
+        ///     "command": [
+        ///         "rust-project",
+        ///         "develop-json",
+        ///         {arg}
+        ///     ],
+        ///     "progressLabel": "rust-analyzer",
+        ///     "filesToWatch": [
+        ///         "BUCK",
+        ///     ],
+        /// }
+        /// ```
+        ///
+        /// ## On `DiscoverWorkspaceConfig::command`
+        ///
+        /// **Warning**: This format is provisional and subject to change.
+        ///
+        /// [`DiscoverWorkspaceConfig::command`] *must* return a JSON object
+        /// corresponding to `DiscoverProjectData::Finished`:
+        ///
+        /// ```norun
+        /// #[derive(Debug, Clone, Deserialize, Serialize)]
+        /// #[serde(tag = "kind")]
+        /// #[serde(rename_all = "snake_case")]
+        /// enum DiscoverProjectData {
+        ///     Finished { buildfile: Utf8PathBuf, project: ProjectJsonData },
+        ///     Error { error: String, source: Option<String> },
+        ///     Progress { message: String },
+        /// }
+        /// ```
+        ///
+        /// As JSON, `DiscoverProjectData::Finished` is:
+        ///
+        /// ```json
+        /// {
+        ///     // the internally-tagged representation of the enum.
+        ///     "kind": "finished",
+        ///     // the file used by a non-Cargo build system to define
+        ///     // a package or target.
+        ///     "buildfile": "rust-analyzer/BUILD",
+        ///     // the contents of a rust-project.json, elided for brevity
+        ///     "project": {
+        ///         "sysroot": "foo",
+        ///         "crates": []
+        ///     }
+        /// }
+        /// ```
+        ///
+        /// It is encouraged, but not required, to use the other variants on
+        /// `DiscoverProjectData` to provide a more polished end-user experience.
+        ///
+        /// `DiscoverWorkspaceConfig::command` may *optionally* include an `{arg}`,
+        /// which will be substituted with the JSON-serialized form of the following
+        /// enum:
+        ///
+        /// ```norun
+        /// #[derive(PartialEq, Clone, Debug, Serialize)]
+        /// #[serde(rename_all = "camelCase")]
+        /// pub enum DiscoverArgument {
+        ///    Path(AbsPathBuf),
+        ///    Buildfile(AbsPathBuf),
+        /// }
+        /// ```
+        ///
+        /// The JSON representation of `DiscoverArgument::Path` is:
+        ///
+        /// ```json
+        /// {
+        ///     "path": "src/main.rs"
+        /// }
+        /// ```
+        ///
+        /// Similarly, the JSON representation of `DiscoverArgument::Buildfile` is:
+        ///
+        /// ```
+        /// {
+        ///     "buildfile": "BUILD"
+        /// }
+        /// ```
+        ///
+        /// `DiscoverArgument::Path` is used to find and generate a `rust-project.json`,
+        /// and therefore, a workspace, whereas `DiscoverArgument::buildfile` is used to
+        /// to update an existing workspace. As a reference for implementors,
+        /// buck2's `rust-project` will likely be useful:
+        /// https://github.com/facebook/buck2/tree/main/integrations/rust-project.
+        workspace_discoverConfig: Option<DiscoverWorkspaceConfig> = None,
     }
 }
 
@@ -924,6 +1020,21 @@ impl Config {
         );
         (config, e, should_update)
     }
+
+    pub fn add_linked_projects(&mut self, data: ProjectJsonData, buildfile: AbsPathBuf) {
+        let linked_projects = &mut self.client_config.0.global.linkedProjects;
+
+        let new_project = ManifestOrProjectJson::DiscoveredProjectJson { data, buildfile };
+        match linked_projects {
+            Some(projects) => {
+                match projects.iter_mut().find(|p| p.manifest() == new_project.manifest()) {
+                    Some(p) => *p = new_project,
+                    None => projects.push(new_project),
+                }
+            }
+            None => *linked_projects = Some(vec![new_project]),
+        }
+    }
 }
 
 #[derive(Default, Debug)]
@@ -988,6 +1099,14 @@ impl From<ProjectJson> for LinkedProject {
     }
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct DiscoverWorkspaceConfig {
+    pub command: Vec<String>,
+    pub progress_label: String,
+    pub files_to_watch: Vec<String>,
+}
+
 pub struct CallInfoConfig {
     pub params_only: bool,
     pub docs: bool,
@@ -1528,15 +1647,27 @@ impl Config {
     pub fn has_linked_projects(&self) -> bool {
         !self.linkedProjects().is_empty()
     }
-    pub fn linked_manifests(&self) -> impl Iterator<Item = &Utf8Path> + '_ {
+
+    pub fn linked_manifests(&self) -> impl Iterator<Item = &AbsPath> + '_ {
         self.linkedProjects().iter().filter_map(|it| match it {
             ManifestOrProjectJson::Manifest(p) => Some(&**p),
-            ManifestOrProjectJson::ProjectJson(_) => None,
+            // despite having a buildfile, using this variant as a manifest
+            // will fail.
+            ManifestOrProjectJson::DiscoveredProjectJson { .. } => None,
+            ManifestOrProjectJson::ProjectJson { .. } => None,
         })
     }
+
     pub fn has_linked_project_jsons(&self) -> bool {
-        self.linkedProjects().iter().any(|it| matches!(it, ManifestOrProjectJson::ProjectJson(_)))
+        self.linkedProjects()
+            .iter()
+            .any(|it| matches!(it, ManifestOrProjectJson::ProjectJson { .. }))
     }
+
+    pub fn discover_workspace_config(&self) -> Option<&DiscoverWorkspaceConfig> {
+        self.workspace_discoverConfig().as_ref()
+    }
+
     pub fn linked_or_discovered_projects(&self) -> Vec<LinkedProject> {
         match self.linkedProjects().as_slice() {
             [] => {
@@ -1561,6 +1692,12 @@ impl Config {
                             .ok()
                             .map(Into::into)
                     }
+                    ManifestOrProjectJson::DiscoveredProjectJson { data, buildfile } => {
+                        let root_path =
+                            buildfile.parent().expect("Unable to get parent of buildfile");
+
+                        Some(ProjectJson::new(None, root_path, data.clone()).into())
+                    }
                     ManifestOrProjectJson::ProjectJson(it) => {
                         Some(ProjectJson::new(None, &self.root_path, it.clone()).into())
                     }
@@ -2101,11 +2238,49 @@ mod single_or_array {
     }
 }
 
-#[derive(Serialize, Deserialize, Debug, Clone)]
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
 #[serde(untagged)]
 enum ManifestOrProjectJson {
-    Manifest(Utf8PathBuf),
+    Manifest(
+        #[serde(serialize_with = "serialize_abs_pathbuf")]
+        #[serde(deserialize_with = "deserialize_abs_pathbuf")]
+        AbsPathBuf,
+    ),
     ProjectJson(ProjectJsonData),
+    DiscoveredProjectJson {
+        data: ProjectJsonData,
+        #[serde(serialize_with = "serialize_abs_pathbuf")]
+        #[serde(deserialize_with = "deserialize_abs_pathbuf")]
+        buildfile: AbsPathBuf,
+    },
+}
+
+fn deserialize_abs_pathbuf<'de, D>(de: D) -> std::result::Result<AbsPathBuf, D::Error>
+where
+    D: serde::de::Deserializer<'de>,
+{
+    let path = String::deserialize(de)?;
+
+    AbsPathBuf::try_from(path.as_ref())
+        .map_err(|err| serde::de::Error::custom(format!("invalid path name: {err:?}")))
+}
+
+fn serialize_abs_pathbuf<S>(path: &AbsPathBuf, se: S) -> Result<S::Ok, S::Error>
+where
+    S: serde::Serializer,
+{
+    let path: &Utf8Path = path.as_ref();
+    se.serialize_str(path.as_str())
+}
+
+impl ManifestOrProjectJson {
+    fn manifest(&self) -> Option<&AbsPath> {
+        match self {
+            ManifestOrProjectJson::Manifest(manifest) => Some(manifest),
+            ManifestOrProjectJson::DiscoveredProjectJson { buildfile, .. } => Some(buildfile),
+            ManifestOrProjectJson::ProjectJson(_) => None,
+        }
+    }
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone)]
@@ -3084,6 +3259,29 @@ fn field_props(field: &str, ty: &str, doc: &[&str], default: &str) -> serde_json
                 },
             ],
         },
+        "Option<DiscoverWorkspaceConfig>" => set! {
+            "anyOf": [
+                {
+                    "type": "null"
+                },
+                {
+                    "type": "object",
+                    "properties": {
+                        "command": {
+                            "type": "array",
+                            "items": { "type": "string" }
+                        },
+                        "progressLabel": {
+                            "type": "string"
+                        },
+                        "filesToWatch": {
+                            "type": "array",
+                            "items": { "type": "string" }
+                        },
+                    }
+                }
+            ]
+        },
         _ => panic!("missing entry for {ty}: {default} (field {field})"),
     }
 

crates/rust-analyzer/src/global_state.rs

@@ -6,7 +6,7 @@
 use std::{ops::Not as _, time::Instant};
 
 use crossbeam_channel::{unbounded, Receiver, Sender};
-use flycheck::FlycheckHandle;
+use flycheck::{project_json, FlycheckHandle};
 use hir::ChangeWithProcMacros;
 use ide::{Analysis, AnalysisHost, Cancellable, FileId, SourceRootId};
 use ide_db::base_db::{CrateId, ProcMacroPaths, SourceDatabaseExt};
@@ -20,9 +20,9 @@ use parking_lot::{
 use proc_macro_api::ProcMacroServer;
 use project_model::{ManifestPath, ProjectWorkspace, ProjectWorkspaceKind, WorkspaceBuildScripts};
 use rustc_hash::{FxHashMap, FxHashSet};
-use tracing::{span, Level};
+use tracing::{span, trace, Level};
 use triomphe::Arc;
-use vfs::{AnchoredPathBuf, ChangeKind, Vfs};
+use vfs::{AbsPathBuf, AnchoredPathBuf, ChangeKind, Vfs};
 
 use crate::{
     config::{Config, ConfigChange, ConfigErrors},
@@ -41,6 +41,11 @@ use crate::{
     task_pool::{TaskPool, TaskQueue},
 };
 
+pub(crate) struct FetchWorkspaceRequest {
+    pub(crate) path: Option<AbsPathBuf>,
+    pub(crate) force_crate_graph_reload: bool,
+}
+
 // Enforces drop order
 pub(crate) struct Handle<H, C> {
     pub(crate) handle: H,
@@ -95,6 +100,11 @@ pub(crate) struct GlobalState {
     pub(crate) test_run_receiver: Receiver<flycheck::CargoTestMessage>,
     pub(crate) test_run_remaining_jobs: usize,
 
+    // Project loading
+    pub(crate) discover_handle: Option<project_json::DiscoverHandle>,
+    pub(crate) discover_sender: Sender<project_json::DiscoverProjectMessage>,
+    pub(crate) discover_receiver: Receiver<project_json::DiscoverProjectMessage>,
+
     // VFS
     pub(crate) loader: Handle<Box<dyn vfs::loader::Handle>, Receiver<vfs::loader::Message>>,
     pub(crate) vfs: Arc<RwLock<(vfs::Vfs, IntMap<FileId, LineEndings>)>>,
@@ -134,11 +144,12 @@ pub(crate) struct GlobalState {
 
     // op queues
     pub(crate) fetch_workspaces_queue:
-        OpQueue<bool, Option<(Vec<anyhow::Result<ProjectWorkspace>>, bool)>>,
+        OpQueue<FetchWorkspaceRequest, Option<(Vec<anyhow::Result<ProjectWorkspace>>, bool)>>,
     pub(crate) fetch_build_data_queue:
         OpQueue<(), (Arc<Vec<ProjectWorkspace>>, Vec<anyhow::Result<WorkspaceBuildScripts>>)>,
     pub(crate) fetch_proc_macros_queue: OpQueue<Vec<ProcMacroPaths>, bool>,
     pub(crate) prime_caches_queue: OpQueue,
+    pub(crate) discover_workspace_queue: OpQueue,
 
     /// A deferred task queue.
     ///
@@ -146,7 +157,7 @@ pub(crate) struct GlobalState {
     /// handlers, as accessing the database may block latency-sensitive
     /// interactions and should be moved away from the main thread.
     ///
-    /// For certain features, such as [`lsp_ext::UnindexedProjectParams`],
+    /// For certain features, such as [`GlobalState::handle_discover_msg`],
     /// this queue should run only *after* [`GlobalState::process_changes`] has
     /// been called.
     pub(crate) deferred_task_queue: TaskQueue,
@@ -202,6 +213,9 @@ impl GlobalState {
         }
         let (flycheck_sender, flycheck_receiver) = unbounded();
         let (test_run_sender, test_run_receiver) = unbounded();
+
+        let (discover_sender, discover_receiver) = unbounded();
+
         let mut this = GlobalState {
             sender,
             req_queue: ReqQueue::default(),
@@ -233,6 +247,10 @@ impl GlobalState {
             test_run_receiver,
             test_run_remaining_jobs: 0,
 
+            discover_handle: None,
+            discover_sender,
+            discover_receiver,
+
             vfs: Arc::new(RwLock::new((vfs::Vfs::default(), IntMap::default()))),
             vfs_config_version: 0,
             vfs_progress_config_version: 0,
@@ -247,6 +265,7 @@ impl GlobalState {
             fetch_proc_macros_queue: OpQueue::default(),
 
             prime_caches_queue: OpQueue::default(),
+            discover_workspace_queue: OpQueue::default(),
 
             deferred_task_queue: task_queue,
         };
@@ -296,11 +315,24 @@ impl GlobalState {
                         modified_rust_files.push(file.file_id);
                     }
 
+                    let additional_files = self
+                        .config
+                        .discover_workspace_config()
+                        .map(|cfg| {
+                            cfg.files_to_watch.iter().map(String::as_str).collect::<Vec<&str>>()
+                        })
+                        .unwrap_or_default();
+
                     let path = path.to_path_buf();
                     if file.is_created_or_deleted() {
                         workspace_structure_change.get_or_insert((path, false)).1 |=
                             self.crate_graph_file_dependencies.contains(vfs_path);
-                    } else if reload::should_refresh_for_change(&path, file.kind()) {
+                    } else if reload::should_refresh_for_change(
+                        &path,
+                        file.kind(),
+                        &additional_files,
+                    ) {
+                        trace!(?path, kind = ?file.kind(), "refreshing for a change");
                         workspace_structure_change.get_or_insert((path.clone(), false));
                     }
                 }
@@ -419,7 +451,7 @@ impl GlobalState {
 
                 self.fetch_workspaces_queue.request_op(
                     format!("workspace vfs file change: {path}"),
-                    force_crate_graph_reload,
+                    FetchWorkspaceRequest { path: Some(path.to_owned()), force_crate_graph_reload },
                 );
             }
         }

crates/rust-analyzer/src/handlers/notification.rs

@@ -14,7 +14,7 @@ use vfs::{AbsPathBuf, ChangeKind, VfsPath};
 
 use crate::{
     config::{Config, ConfigChange},
-    global_state::GlobalState,
+    global_state::{FetchWorkspaceRequest, GlobalState},
     lsp::{from_proto, utils::apply_document_changes},
     lsp_ext::{self, RunFlycheckParams},
     mem_docs::DocumentData,
@@ -73,7 +73,9 @@ pub(crate) fn handle_did_open_text_document(
 
         tracing::info!("New file content set {:?}", params.text_document.text);
         state.vfs.write().0.set_file_contents(path, Some(params.text_document.text.into_bytes()));
-        if state.config.notifications().unindexed_project {
+        if state.config.discover_workspace_config().is_some()
+            || state.config.notifications().unindexed_project
+        {
             tracing::debug!("queuing task");
             let _ = state
                 .deferred_task_queue
@@ -150,15 +152,29 @@ pub(crate) fn handle_did_save_text_document(
 
     if let Ok(vfs_path) = from_proto::vfs_path(&params.text_document.uri) {
         // Re-fetch workspaces if a workspace related file has changed
-        if let Some(abs_path) = vfs_path.as_path() {
+        if let Some(path) = vfs_path.as_path() {
-            if reload::should_refresh_for_change(abs_path, ChangeKind::Modify) {
+            let additional_files = &state
-                state
+                .config
-                    .fetch_workspaces_queue
+                .discover_workspace_config()
-                    .request_op(format!("workspace vfs file change saved {abs_path}"), false);
+                .map(|cfg| cfg.files_to_watch.iter().map(String::as_str).collect::<Vec<&str>>())
-            } else if state.detached_files.contains(abs_path) {
+                .unwrap_or_default();
-                state
+
-                    .fetch_workspaces_queue
+            if reload::should_refresh_for_change(path, ChangeKind::Modify, additional_files) {
-                    .request_op(format!("detached file saved {abs_path}"), false);
+                state.fetch_workspaces_queue.request_op(
+                    format!("workspace vfs file change saved {path}"),
+                    FetchWorkspaceRequest {
+                        path: Some(path.to_owned()),
+                        force_crate_graph_reload: false,
+                    },
+                );
+            } else if state.detached_files.contains(path) {
+                state.fetch_workspaces_queue.request_op(
+                    format!("detached file saved {path}"),
+                    FetchWorkspaceRequest {
+                        path: Some(path.to_owned()),
+                        force_crate_graph_reload: false,
+                    },
+                );
             }
         }
 
@@ -240,7 +256,9 @@ pub(crate) fn handle_did_change_workspace_folders(
 
     if !config.has_linked_projects() && config.detached_files().is_empty() {
         config.rediscover_workspaces();
-        state.fetch_workspaces_queue.request_op("client workspaces changed".to_owned(), false)
+
+        let req = FetchWorkspaceRequest { path: None, force_crate_graph_reload: false };
+        state.fetch_workspaces_queue.request_op("client workspaces changed".to_owned(), req);
     }
 
     Ok(())

crates/rust-analyzer/src/handlers/request.rs

@@ -37,7 +37,7 @@ use vfs::{AbsPath, AbsPathBuf, FileId, VfsPath};
 use crate::{
     config::{Config, RustfmtConfig, WorkspaceSymbolConfig},
     diff::diff,
-    global_state::{GlobalState, GlobalStateSnapshot},
+    global_state::{FetchWorkspaceRequest, GlobalState, GlobalStateSnapshot},
     hack_recover_crate_name,
     line_index::LineEndings,
     lsp::{
@@ -57,7 +57,8 @@ pub(crate) fn handle_workspace_reload(state: &mut GlobalState, _: ()) -> anyhow:
     state.proc_macro_clients = Arc::from_iter([]);
     state.build_deps_changed = false;
 
-    state.fetch_workspaces_queue.request_op("reload workspace request".to_owned(), false);
+    let req = FetchWorkspaceRequest { path: None, force_crate_graph_reload: false };
+    state.fetch_workspaces_queue.request_op("reload workspace request".to_owned(), req);
     Ok(())
 }
 

crates/rust-analyzer/src/lsp/ext.rs

@@ -531,7 +531,7 @@ pub struct ServerStatusParams {
     pub message: Option<String>,
 }
 
-#[derive(Serialize, Deserialize, Clone, Copy, PartialEq, Eq)]
+#[derive(Serialize, Deserialize, Clone, Copy, PartialEq, Eq, Debug)]
 #[serde(rename_all = "camelCase")]
 pub enum Health {
     Ok,

crates/rust-analyzer/src/lsp/utils.rs

@@ -74,7 +74,6 @@ impl GlobalState {
         }
     }
 
-    /// Sends a notification to the client containing the error `message`.
     /// If `additional_info` is [`Some`], appends a note to the notification telling to check the logs.
     /// This will always log `message` + `additional_info` to the server's error log.
     pub(crate) fn show_and_log_error(&mut self, message: String, additional_info: Option<String>) {

crates/rust-analyzer/src/main_loop.rs

@@ -9,18 +9,19 @@ use std::{
 
 use always_assert::always;
 use crossbeam_channel::{select, Receiver};
+use flycheck::project_json;
 use ide_db::base_db::{SourceDatabase, SourceDatabaseExt, VfsPath};
 use lsp_server::{Connection, Notification, Request};
 use lsp_types::{notification::Notification as _, TextDocumentIdentifier};
 use stdx::thread::ThreadIntent;
 use tracing::{span, Level};
-use vfs::FileId;
+use vfs::{AbsPathBuf, FileId};
 
 use crate::{
     config::Config,
     diagnostics::{fetch_native_diagnostics, DiagnosticsGeneration},
     dispatch::{NotificationDispatcher, RequestDispatcher},
-    global_state::{file_id_to_url, url_to_file_id, GlobalState},
+    global_state::{file_id_to_url, url_to_file_id, FetchWorkspaceRequest, GlobalState},
     hack_recover_crate_name,
     lsp::{
         from_proto, to_proto,
@@ -62,6 +63,7 @@ enum Event {
     Vfs(vfs::loader::Message),
     Flycheck(flycheck::Message),
     TestResult(flycheck::CargoTestMessage),
+    DiscoverProject(project_json::DiscoverProjectMessage),
 }
 
 impl fmt::Display for Event {
@@ -73,6 +75,7 @@ impl fmt::Display for Event {
             Event::Flycheck(_) => write!(f, "Event::Flycheck"),
             Event::QueuedTask(_) => write!(f, "Event::QueuedTask"),
             Event::TestResult(_) => write!(f, "Event::TestResult"),
+            Event::DiscoverProject(_) => write!(f, "Event::DiscoverProject"),
         }
     }
 }
@@ -86,6 +89,7 @@ pub(crate) enum QueuedTask {
 #[derive(Debug)]
 pub(crate) enum Task {
     Response(lsp_server::Response),
+    DiscoverLinkedProjects(DiscoverProjectParam),
     ClientNotification(lsp_ext::UnindexedProjectParams),
     Retry(lsp_server::Request),
     Diagnostics(DiagnosticsGeneration, Vec<(FileId, Vec<lsp_types::Diagnostic>)>),
@@ -97,6 +101,12 @@ pub(crate) enum Task {
     BuildDepsHaveChanged,
 }
 
+#[derive(Debug)]
+pub(crate) enum DiscoverProjectParam {
+    Buildfile(AbsPathBuf),
+    Path(AbsPathBuf),
+}
+
 #[derive(Debug)]
 pub(crate) enum PrimeCachesProgress {
     Begin,
@@ -134,6 +144,7 @@ impl fmt::Debug for Event {
             Event::Vfs(it) => fmt::Debug::fmt(it, f),
             Event::Flycheck(it) => fmt::Debug::fmt(it, f),
             Event::TestResult(it) => fmt::Debug::fmt(it, f),
+            Event::DiscoverProject(it) => fmt::Debug::fmt(it, f),
         }
     }
 }
@@ -143,14 +154,24 @@ impl GlobalState {
         self.update_status_or_notify();
 
         if self.config.did_save_text_document_dynamic_registration() {
-            self.register_did_save_capability();
+            let additional_patterns = self
+                .config
+                .discover_workspace_config()
+                .map(|cfg| cfg.files_to_watch.clone().into_iter())
+                .into_iter()
+                .flatten()
+                .map(|f| format!("**/{f}"));
+            self.register_did_save_capability(additional_patterns);
         }
 
-        self.fetch_workspaces_queue.request_op("startup".to_owned(), false);
+        if self.config.discover_workspace_config().is_none() {
-        if let Some((cause, force_crate_graph_reload)) =
+            let req = FetchWorkspaceRequest { path: None, force_crate_graph_reload: false };
-            self.fetch_workspaces_queue.should_start_op()
+            self.fetch_workspaces_queue.request_op("startup".to_owned(), req);
-        {
+            if let Some((cause, FetchWorkspaceRequest { path, force_crate_graph_reload })) =
-            self.fetch_workspaces(cause, force_crate_graph_reload);
+                self.fetch_workspaces_queue.should_start_op()
+            {
+                self.fetch_workspaces(cause, path, force_crate_graph_reload);
+            }
         }
 
         while let Some(event) = self.next_event(&inbox) {
@@ -167,32 +188,36 @@ impl GlobalState {
         anyhow::bail!("client exited without proper shutdown sequence")
     }
 
-    fn register_did_save_capability(&mut self) {
+    fn register_did_save_capability(&mut self, additional_patterns: impl Iterator<Item = String>) {
+        let additional_filters = additional_patterns.map(|pattern| lsp_types::DocumentFilter {
+            language: None,
+            scheme: None,
+            pattern: (Some(pattern)),
+        });
+
+        let mut selectors = vec![
+            lsp_types::DocumentFilter {
+                language: None,
+                scheme: None,
+                pattern: Some("**/*.rs".into()),
+            },
+            lsp_types::DocumentFilter {
+                language: None,
+                scheme: None,
+                pattern: Some("**/Cargo.toml".into()),
+            },
+            lsp_types::DocumentFilter {
+                language: None,
+                scheme: None,
+                pattern: Some("**/Cargo.lock".into()),
+            },
+        ];
+        selectors.extend(additional_filters);
+
         let save_registration_options = lsp_types::TextDocumentSaveRegistrationOptions {
             include_text: Some(false),
             text_document_registration_options: lsp_types::TextDocumentRegistrationOptions {
-                document_selector: Some(vec![
+                document_selector: Some(selectors),
-                    lsp_types::DocumentFilter {
-                        language: None,
-                        scheme: None,
-                        pattern: Some("**/*.rs".into()),
-                    },
-                    lsp_types::DocumentFilter {
-                        language: None,
-                        scheme: None,
-                        pattern: Some("**/Cargo.toml".into()),
-                    },
-                    lsp_types::DocumentFilter {
-                        language: None,
-                        scheme: None,
-                        pattern: Some("**/Cargo.lock".into()),
-                    },
-                    lsp_types::DocumentFilter {
-                        language: None,
-                        scheme: None,
-                        pattern: Some("**/rust-analyzer.toml".into()),
-                    },
-                ]),
             },
         };
 
@@ -230,6 +255,8 @@ impl GlobalState {
             recv(self.test_run_receiver) -> task =>
                 Some(Event::TestResult(task.unwrap())),
 
+            recv(self.discover_receiver) -> task =>
+                Some(Event::DiscoverProject(task.unwrap())),
         }
     }
 
@@ -340,6 +367,13 @@ impl GlobalState {
                     self.handle_cargo_test_msg(message);
                 }
             }
+            Event::DiscoverProject(message) => {
+                self.handle_discover_msg(message);
+                // Coalesce many project discovery events into a single loop turn.
+                while let Ok(message) = self.discover_receiver.try_recv() {
+                    self.handle_discover_msg(message);
+                }
+            }
         }
         let event_handling_duration = loop_start.elapsed();
 
@@ -427,11 +461,13 @@ impl GlobalState {
             }
         }
 
-        if self.config.cargo_autoreload_config() {
+        if self.config.cargo_autoreload_config()
-            if let Some((cause, force_crate_graph_reload)) =
+            || self.config.discover_workspace_config().is_some()
+        {
+            if let Some((cause, FetchWorkspaceRequest { path, force_crate_graph_reload })) =
                 self.fetch_workspaces_queue.should_start_op()
             {
-                self.fetch_workspaces(cause, force_crate_graph_reload);
+                self.fetch_workspaces(cause, path, force_crate_graph_reload);
             }
         }
 
@@ -647,6 +683,35 @@ impl GlobalState {
 
                 self.report_progress("Fetching", state, msg, None, None);
             }
+            Task::DiscoverLinkedProjects(arg) => {
+                if let Some(cfg) = self.config.discover_workspace_config() {
+                    if !self.discover_workspace_queue.op_in_progress() {
+                        // the clone is unfortunately necessary to avoid a borrowck error when
+                        // `self.report_progress` is called later
+                        let title = &cfg.progress_label.clone();
+                        let command = cfg.command.clone();
+                        let discover =
+                            project_json::Discover::new(self.discover_sender.clone(), command);
+
+                        self.report_progress(title, Progress::Begin, None, None, None);
+                        self.discover_workspace_queue
+                            .request_op("Discovering workspace".to_owned(), ());
+                        let _ = self.discover_workspace_queue.should_start_op();
+
+                        let arg = match arg {
+                            DiscoverProjectParam::Buildfile(it) => {
+                                project_json::DiscoverArgument::Buildfile(it)
+                            }
+                            DiscoverProjectParam::Path(it) => {
+                                project_json::DiscoverArgument::Path(it)
+                            }
+                        };
+
+                        let handle = discover.spawn(arg).unwrap();
+                        self.discover_handle = Some(handle);
+                    }
+                }
+            }
             Task::FetchBuildData(progress) => {
                 let (state, msg) = match progress {
                     BuildDataProgress::Begin => (Some(Progress::Begin), None),
@@ -755,10 +820,17 @@ impl GlobalState {
                     let id = from_proto::file_id(&snap, &uri).expect("unable to get FileId");
                     if let Ok(crates) = &snap.analysis.crates_for(id) {
                         if crates.is_empty() {
-                            let params = lsp_ext::UnindexedProjectParams {
+                            if snap.config.discover_workspace_config().is_some() {
-                                text_documents: vec![lsp_types::TextDocumentIdentifier { uri }],
+                                let path =
+                                    from_proto::abs_path(&uri).expect("Unable to get AbsPath");
+                                let arg = DiscoverProjectParam::Path(path);
+                                sender.send(Task::DiscoverLinkedProjects(arg)).unwrap();
+                            } else if snap.config.notifications().unindexed_project {
+                                let params = lsp_ext::UnindexedProjectParams {
+                                    text_documents: vec![lsp_types::TextDocumentIdentifier { uri }],
+                                };
+                                sender.send(Task::ClientNotification(params)).unwrap();
                             };
-                            sender.send(Task::ClientNotification(params)).unwrap();
                         } else {
                             tracing::debug!(?uri, "is indexed");
                         }
@@ -787,6 +859,33 @@ impl GlobalState {
         }
     }
 
+    fn handle_discover_msg(&mut self, message: project_json::DiscoverProjectMessage) {
+        let title = self
+            .config
+            .discover_workspace_config()
+            .map(|cfg| cfg.progress_label.clone())
+            .expect("No title could be found; this is a bug");
+        match message {
+            project_json::DiscoverProjectMessage::Finished { project, buildfile } => {
+                self.report_progress(&title, Progress::End, None, None, None);
+                self.discover_workspace_queue.op_completed(());
+
+                let mut config = Config::clone(&*self.config);
+                config.add_linked_projects(project, buildfile);
+                self.update_configuration(config);
+            }
+            project_json::DiscoverProjectMessage::Progress { message } => {
+                self.report_progress(&title, Progress::Report, Some(message), None, None)
+            }
+            project_json::DiscoverProjectMessage::Error { error, source } => {
+                let message = format!("Project discovery failed: {error}");
+                self.discover_workspace_queue.op_completed(());
+                self.show_and_log_error(message.clone(), source);
+                self.report_progress(&title, Progress::End, Some(message), None, None)
+            }
+        }
+    }
+
     fn handle_cargo_test_msg(&mut self, message: flycheck::CargoTestMessage) {
         match message {
             flycheck::CargoTestMessage::Test { name, state } => {

crates/rust-analyzer/src/op_queue.rs

@@ -3,6 +3,7 @@
 
 pub(crate) type Cause = String;
 
+#[derive(Debug)]
 pub(crate) struct OpQueue<Args = (), Output = ()> {
     op_requested: Option<(Cause, Args)>,
     op_in_progress: bool,

crates/rust-analyzer/src/reload.rs

@@ -33,11 +33,12 @@ use vfs::{AbsPath, AbsPathBuf, ChangeKind};
 
 use crate::{
     config::{Config, FilesWatcher, LinkedProject},
-    global_state::GlobalState,
+    global_state::{FetchWorkspaceRequest, GlobalState},
     lsp_ext,
-    main_loop::Task,
+    main_loop::{DiscoverProjectParam, Task},
     op_queue::Cause,
 };
+use tracing::{debug, info};
 
 #[derive(Debug)]
 pub(crate) enum ProjectWorkspaceProgress {
@@ -66,6 +67,7 @@ impl GlobalState {
             || self.fetch_workspaces_queue.op_in_progress()
             || self.fetch_build_data_queue.op_in_progress()
             || self.fetch_proc_macros_queue.op_in_progress()
+            || self.discover_workspace_queue.op_in_progress()
             || self.vfs_progress_config_version < self.vfs_config_version
             || self.vfs_progress_n_done < self.vfs_progress_n_total)
     }
@@ -81,9 +83,11 @@ impl GlobalState {
                 &self.config.lru_query_capacities_config().cloned().unwrap_or_default(),
             );
         }
+
         if self.config.linked_or_discovered_projects() != old_config.linked_or_discovered_projects()
         {
-            self.fetch_workspaces_queue.request_op("discovered projects changed".to_owned(), false)
+            let req = FetchWorkspaceRequest { path: None, force_crate_graph_reload: false };
+            self.fetch_workspaces_queue.request_op("discovered projects changed".to_owned(), req)
         } else if self.config.flycheck() != old_config.flycheck() {
             self.reload_flycheck();
         }
@@ -109,6 +113,7 @@ impl GlobalState {
         if !self.config.cargo_autoreload()
             && self.is_quiescent()
             && self.fetch_workspaces_queue.op_requested()
+            && self.config.discover_workspace_config().is_none()
         {
             status.health |= lsp_ext::Health::Warning;
             message.push_str("Auto-reloading is disabled and the workspace has changed, a manual workspace reload is required.\n\n");
@@ -124,7 +129,6 @@ impl GlobalState {
             status.health |= lsp_ext::Health::Warning;
             message.push_str("Failed to run build scripts of some packages.\n\n");
         }
-
         if let Some(err) = &self.config_errors {
             status.health |= lsp_ext::Health::Warning;
             format_to!(message, "{err}\n");
@@ -217,8 +221,13 @@ impl GlobalState {
         status
     }
 
-    pub(crate) fn fetch_workspaces(&mut self, cause: Cause, force_crate_graph_reload: bool) {
+    pub(crate) fn fetch_workspaces(
-        tracing::info!(%cause, "will fetch workspaces");
+        &mut self,
+        cause: Cause,
+        path: Option<AbsPathBuf>,
+        force_crate_graph_reload: bool,
+    ) {
+        info!(%cause, "will fetch workspaces");
 
         self.task_pool.handle.spawn_with_sender(ThreadIntent::Worker, {
             let linked_projects = self.config.linked_or_discovered_projects();
@@ -231,6 +240,10 @@ impl GlobalState {
                 .filter_map(Result::ok)
                 .collect();
             let cargo_config = self.config.cargo();
+            let discover_command = self.config.discover_workspace_config().cloned();
+            let is_quiescent = !(self.discover_workspace_queue.op_in_progress()
+                || self.vfs_progress_config_version < self.vfs_config_version
+                || self.vfs_progress_n_done < self.vfs_progress_n_total);
 
             move |sender| {
                 let progress = {
@@ -244,10 +257,28 @@ impl GlobalState {
 
                 sender.send(Task::FetchWorkspace(ProjectWorkspaceProgress::Begin)).unwrap();
 
+                if let (Some(_command), Some(path)) = (&discover_command, &path) {
+                    let build = linked_projects.iter().find_map(|project| match project {
+                        LinkedProject::InlineJsonProject(it) => it.crate_by_buildfile(path),
+                        _ => None,
+                    });
+
+                    if let Some(build) = build {
+                        if is_quiescent {
+                            let path = AbsPathBuf::try_from(build.build_file)
+                                .expect("Unable to convert to an AbsPath");
+                            let arg = DiscoverProjectParam::Buildfile(path);
+                            sender.send(Task::DiscoverLinkedProjects(arg)).unwrap();
+                        }
+                    }
+                }
+
                 let mut workspaces = linked_projects
                     .iter()
                     .map(|project| match project {
                         LinkedProject::ProjectManifest(manifest) => {
+                            debug!(path = %manifest, "loading project from manifest");
+
                             project_model::ProjectWorkspace::load(
                                 manifest.clone(),
                                 &cargo_config,
@@ -255,12 +286,13 @@ impl GlobalState {
                             )
                         }
                         LinkedProject::InlineJsonProject(it) => {
-                            Ok(project_model::ProjectWorkspace::load_inline(
+                            let workspace = project_model::ProjectWorkspace::load_inline(
                                 it.clone(),
                                 cargo_config.target.as_deref(),
                                 &cargo_config.extra_env,
                                 &cargo_config.cfg_overrides,
-                            ))
+                            );
+                            Ok(workspace)
                         }
                     })
                     .collect::<Vec<_>>();
@@ -286,7 +318,7 @@ impl GlobalState {
                     ));
                 }
 
-                tracing::info!("did fetch workspaces {:?}", workspaces);
+                info!(?workspaces, "did fetch workspaces");
                 sender
                     .send(Task::FetchWorkspace(ProjectWorkspaceProgress::End(
                         workspaces,
@@ -298,7 +330,7 @@ impl GlobalState {
     }
 
     pub(crate) fn fetch_build_data(&mut self, cause: Cause) {
-        tracing::info!(%cause, "will fetch build data");
+        info!(%cause, "will fetch build data");
         let workspaces = Arc::clone(&self.workspaces);
         let config = self.config.cargo();
         let root_path = self.config.root_path().clone();
@@ -324,7 +356,7 @@ impl GlobalState {
     }
 
     pub(crate) fn fetch_proc_macros(&mut self, cause: Cause, paths: Vec<ProcMacroPaths>) {
-        tracing::info!(%cause, "will load proc macros");
+        info!(%cause, "will load proc macros");
         let ignored_proc_macros = self.config.ignored_proc_macros().clone();
         let proc_macro_clients = self.proc_macro_clients.clone();
 
@@ -395,6 +427,7 @@ impl GlobalState {
             return;
         };
 
+        info!(%cause, ?force_reload_crate_graph);
         if self.fetch_workspace_error().is_err() && !self.workspaces.is_empty() {
             if *force_reload_crate_graph {
                 self.recreate_crate_graph(cause);
@@ -416,7 +449,7 @@ impl GlobalState {
         if same_workspaces {
             let (workspaces, build_scripts) = self.fetch_build_data_queue.last_op_result();
             if Arc::ptr_eq(workspaces, &self.workspaces) {
-                tracing::debug!("set build scripts to workspaces");
+                info!("set build scripts to workspaces");
 
                 let workspaces = workspaces
                     .iter()
@@ -428,9 +461,10 @@ impl GlobalState {
                     })
                     .collect::<Vec<_>>();
                 // Workspaces are the same, but we've updated build data.
+                info!("same workspace, but new build data");
                 self.workspaces = Arc::new(workspaces);
             } else {
-                tracing::info!("build scripts do not match the version of the active workspace");
+                info!("build scripts do not match the version of the active workspace");
                 if *force_reload_crate_graph {
                     self.recreate_crate_graph(cause);
                 }
@@ -440,7 +474,7 @@ impl GlobalState {
                 return;
             }
         } else {
-            tracing::debug!("abandon build scripts for workspaces");
+            info!("abandon build scripts for workspaces");
 
             // Here, we completely changed the workspace (Cargo.toml edit), so
             // we don't care about build-script results, they are stale.
@@ -535,7 +569,7 @@ impl GlobalState {
         if (self.proc_macro_clients.is_empty() || !same_workspaces)
             && self.config.expand_proc_macros()
         {
-            tracing::info!("Spawning proc-macro servers");
+            info!("Spawning proc-macro servers");
 
             self.proc_macro_clients = Arc::from_iter(self.workspaces.iter().map(|ws| {
                 let path = match self.config.proc_macro_srv() {
@@ -562,7 +596,7 @@ impl GlobalState {
 
                     _ => Default::default(),
                 };
-                tracing::info!("Using proc-macro server at {path}");
+                info!("Using proc-macro server at {path}");
 
                 ProcMacroServer::spawn(&path, &env).map_err(|err| {
                     tracing::error!(
@@ -588,12 +622,14 @@ impl GlobalState {
         self.source_root_config = project_folders.source_root_config;
         self.local_roots_parent_map = Arc::new(self.source_root_config.source_root_parent_map());
 
+        info!(?cause, "recreating the crate graph");
         self.recreate_crate_graph(cause);
 
-        tracing::info!("did switch workspaces");
+        info!("did switch workspaces");
     }
 
     fn recreate_crate_graph(&mut self, cause: String) {
+        info!(?cause, "Building Crate Graph");
         self.report_progress(
             "Building CrateGraph",
             crate::lsp::utils::Progress::Begin,
@@ -658,12 +694,19 @@ impl GlobalState {
         let Some((last_op_result, _)) = self.fetch_workspaces_queue.last_op_result() else {
             return Ok(());
         };
-        if last_op_result.is_empty() {
+
-            stdx::format_to!(buf, "rust-analyzer failed to discover workspace");
+        if !self.discover_workspace_queue.op_in_progress() {
-        } else {
+            if last_op_result.is_empty() {
-            for ws in last_op_result {
+                stdx::format_to!(buf, "rust-analyzer failed to discover workspace");
-                if let Err(err) = ws {
+            } else {
-                    stdx::format_to!(buf, "rust-analyzer failed to load workspace: {:#}\n", err);
+                for ws in last_op_result {
+                    if let Err(err) = ws {
+                        stdx::format_to!(
+                            buf,
+                            "rust-analyzer failed to load workspace: {:#}\n",
+                            err
+                        );
+                    }
                 }
             }
         }
@@ -818,7 +861,11 @@ pub fn ws_to_crate_graph(
     (crate_graph, proc_macro_paths, layouts, toolchains)
 }
 
-pub(crate) fn should_refresh_for_change(path: &AbsPath, change_kind: ChangeKind) -> bool {
+pub(crate) fn should_refresh_for_change(
+    path: &AbsPath,
+    change_kind: ChangeKind,
+    additional_paths: &[&str],
+) -> bool {
     const IMPLICIT_TARGET_FILES: &[&str] = &["build.rs", "src/main.rs", "src/lib.rs"];
     const IMPLICIT_TARGET_DIRS: &[&str] = &["src/bin", "examples", "tests", "benches"];
 
@@ -830,6 +877,11 @@ pub(crate) fn should_refresh_for_change(path: &AbsPath, change_kind: ChangeKind)
     if let "Cargo.toml" | "Cargo.lock" = file_name {
         return true;
     }
+
+    if additional_paths.contains(&file_name) {
+        return true;
+    }
+
     if change_kind == ChangeKind::Modify {
         return false;
     }

crates/rust-analyzer/src/tracing/config.rs

@@ -48,7 +48,10 @@ where
 
         let writer = self.writer;
 
-        let ra_fmt_layer = tracing_subscriber::fmt::layer().with_writer(writer).with_filter(filter);
+        let ra_fmt_layer = tracing_subscriber::fmt::layer()
+            .with_target(false)
+            .with_writer(writer)
+            .with_filter(filter);
 
         let mut chalk_layer = None;
         if let Some(chalk_filter) = self.chalk_filter {

crates/rust-analyzer/tests/slow-tests/main.rs

@@ -27,7 +27,6 @@ use lsp_types::{
     InlayHint, InlayHintLabel, InlayHintParams, PartialResultParams, Position, Range,
     RenameFilesParams, TextDocumentItem, TextDocumentPositionParams, WorkDoneProgressParams,
 };
-
 use rust_analyzer::lsp::ext::{OnEnter, Runnables, RunnablesParams, UnindexedProject};
 use serde_json::json;
 use stdx::format_to_acc;

docs/dev/lsp-extensions.md

@@ -1,5 +1,5 @@
 <!---
-lsp/ext.rs hash: 39b47906286ad9c
+lsp/ext.rs hash: 278250dba58cd879
 
 If you need to change the above hash to make the test pass, please check if you
 need to adjust this doc as well and ping this issue:

docs/user/generated_config.adoc

@@ -1015,6 +1015,104 @@ Show documentation.
 --
 Whether to insert closing angle brackets when typing an opening angle bracket of a generic argument list.
 --
+[[rust-analyzer.workspace.discoverConfig]]rust-analyzer.workspace.discoverConfig (default: `null`)::
++
+--
+Enables automatic discovery of projects using [`DiscoverWorkspaceConfig::command`].
+
+[`DiscoverWorkspaceConfig`] also requires setting `progress_label` and `files_to_watch`.
+`progress_label` is used for the title in progress indicators, whereas `files_to_watch`
+is used to determine which build system-specific files should be watched in order to
+reload rust-analyzer.
+
+Below is an example of a valid configuration:
+```json
+"rust-analyzer.workspace.discoverConfig": {
+    "command": [
+        "rust-project",
+        "develop-json",
+        {arg}
+    ],
+    "progressLabel": "rust-analyzer",
+    "filesToWatch": [
+        "BUCK",
+    ],
+}
+```
+
+## On `DiscoverWorkspaceConfig::command`
+
+**Warning**: This format is provisional and subject to change.
+
+[`DiscoverWorkspaceConfig::command`] *must* return a JSON object
+corresponding to `DiscoverProjectData::Finished`:
+
+```norun
+#[derive(Debug, Clone, Deserialize, Serialize)]
+#[serde(tag = "kind")]
+#[serde(rename_all = "snake_case")]
+enum DiscoverProjectData {
+    Finished { buildfile: Utf8PathBuf, project: ProjectJsonData },
+    Error { error: String, source: Option<String> },
+    Progress { message: String },
+}
+```
+
+As JSON, `DiscoverProjectData::Finished` is:
+
+```json
+{
+    // the internally-tagged representation of the enum.
+    "kind": "finished",
+    // the file used by a non-Cargo build system to define
+    // a package or target.
+    "buildfile": "rust-analyzer/BUILD",
+    // the contents of a rust-project.json, elided for brevity
+    "project": {
+        "sysroot": "foo",
+        "crates": []
+    }
+}
+```
+
+It is encouraged, but not required, to use the other variants on
+`DiscoverProjectData` to provide a more polished end-user experience.
+
+`DiscoverWorkspaceConfig::command` may *optionally* include an `{arg}`,
+which will be substituted with the JSON-serialized form of the following
+enum:
+
+```norun
+#[derive(PartialEq, Clone, Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub enum DiscoverArgument {
+   Path(AbsPathBuf),
+   Buildfile(AbsPathBuf),
+}
+```
+
+The JSON representation of `DiscoverArgument::Path` is:
+
+```json
+{
+    "path": "src/main.rs"
+}
+```
+
+Similarly, the JSON representation of `DiscoverArgument::Buildfile` is:
+
+```
+{
+    "buildfile": "BUILD"
+}
+```
+
+`DiscoverArgument::Path` is used to find and generate a `rust-project.json`,
+and therefore, a workspace, whereas `DiscoverArgument::buildfile` is used to
+to update an existing workspace. As a reference for implementors,
+buck2's `rust-project` will likely be useful:
+https://github.com/facebook/buck2/tree/main/integrations/rust-project.
+--
 [[rust-analyzer.workspace.symbol.search.kind]]rust-analyzer.workspace.symbol.search.kind (default: `"only_types"`)::
 +
 --

editors/code/package.json

@@ -2595,6 +2595,40 @@
                     }
                 }
             },
+            {
+                "title": "workspace",
+                "properties": {
+                    "rust-analyzer.workspace.discoverConfig": {
+                        "markdownDescription": "Enables automatic discovery of projects using [`DiscoverWorkspaceConfig::command`].\n\n[`DiscoverWorkspaceConfig`] also requires setting `progress_label` and `files_to_watch`.\n`progress_label` is used for the title in progress indicators, whereas `files_to_watch`\nis used to determine which build system-specific files should be watched in order to\nreload rust-analyzer.\n\nBelow is an example of a valid configuration:\n```json\n\"rust-analyzer.workspace.discoverConfig\": {\n        \"command\": [\n                \"rust-project\",\n                \"develop-json\",\n                {arg}\n        ],\n        \"progressLabel\": \"rust-analyzer\",\n        \"filesToWatch\": [\n                \"BUCK\",\n        ],\n}\n```\n\n## On `DiscoverWorkspaceConfig::command`\n\n**Warning**: This format is provisional and subject to change.\n\n[`DiscoverWorkspaceConfig::command`] *must* return a JSON object\ncorresponding to `DiscoverProjectData::Finished`:\n\n```norun\n#[derive(Debug, Clone, Deserialize, Serialize)]\n#[serde(tag = \"kind\")]\n#[serde(rename_all = \"snake_case\")]\nenum DiscoverProjectData {\n        Finished { buildfile: Utf8PathBuf, project: ProjectJsonData },\n        Error { error: String, source: Option<String> },\n        Progress { message: String },\n}\n```\n\nAs JSON, `DiscoverProjectData::Finished` is:\n\n```json\n{\n        // the internally-tagged representation of the enum.\n        \"kind\": \"finished\",\n        // the file used by a non-Cargo build system to define\n        // a package or target.\n        \"buildfile\": \"rust-analyzer/BUILD\",\n        // the contents of a rust-project.json, elided for brevity\n        \"project\": {\n                \"sysroot\": \"foo\",\n                \"crates\": []\n        }\n}\n```\n\nIt is encouraged, but not required, to use the other variants on\n`DiscoverProjectData` to provide a more polished end-user experience.\n\n`DiscoverWorkspaceConfig::command` may *optionally* include an `{arg}`,\nwhich will be substituted with the JSON-serialized form of the following\nenum:\n\n```norun\n#[derive(PartialEq, Clone, Debug, Serialize)]\n#[serde(rename_all = \"camelCase\")]\npub enum DiscoverArgument {\n     Path(AbsPathBuf),\n     Buildfile(AbsPathBuf),\n}\n```\n\nThe JSON representation of `DiscoverArgument::Path` is:\n\n```json\n{\n        \"path\": \"src/main.rs\"\n}\n```\n\nSimilarly, the JSON representation of `DiscoverArgument::Buildfile` is:\n\n```\n{\n        \"buildfile\": \"BUILD\"\n}\n```\n\n`DiscoverArgument::Path` is used to find and generate a `rust-project.json`,\nand therefore, a workspace, whereas `DiscoverArgument::buildfile` is used to\nto update an existing workspace. As a reference for implementors,\nbuck2's `rust-project` will likely be useful:\nhttps://github.com/facebook/buck2/tree/main/integrations/rust-project.",
+                        "default": null,
+                        "anyOf": [
+                            {
+                                "type": "null"
+                            },
+                            {
+                                "type": "object",
+                                "properties": {
+                                    "command": {
+                                        "type": "array",
+                                        "items": {
+                                            "type": "string"
+                                        }
+                                    },
+                                    "progressLabel": {
+                                        "type": "string"
+                                    },
+                                    "filesToWatch": {
+                                        "type": "array",
+                                        "items": {
+                                            "type": "string"
+                                        }
+                                    }
+                                }
+                            }
+                        ]
+                    }
+                }
+            },
             {
                 "title": "workspace",
                 "properties": {