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bors fdcce9384d Auto merge of - khuey:mir-inlining-parameters-debuginfo, r=wesleywiser
Rework MIR inlining debuginfo so function parameters show up in debuggers.

Line numbers of multiply-inlined functions were fixed in  by using a single DISubprogram. That, however, triggered assertions because parameters weren't deduplicated. The "solution" to that in  was to insert a DILexicalScope below the DISubprogram and parent all of the parameters to that scope. That fixed the assertion, but debuggers (including gdb and lldb) don't recognize variables that are not parented to the subprogram itself as parameters, even if they are emitted with DW_TAG_formal_parameter.

Consider the program:

```rust
use std::env;

#[inline(always)]
fn square(n: i32) -> i32 {
    n * n
}

#[inline(never)]
fn square_no_inline(n: i32) -> i32 {
    n * n
}

fn main() {
    let x = square(env::vars().count() as i32);
    let y = square_no_inline(env::vars().count() as i32);
    println!("{x} == {y}");
}
```

When making a release build with debug=2 and rustc 1.82.0-nightly (8b3870784 2024-08-07)

```
(gdb) r
Starting program: /ephemeral/tmp/target/release/tmp [Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Breakpoint 1, tmp::square () at src/main.rs:5
5	    n * n
(gdb) info args
No arguments.
(gdb) info locals
n = 31
(gdb) c
Continuing.

Breakpoint 2, tmp::square_no_inline (n=31) at src/main.rs:10
10	    n * n
(gdb) info args
n = 31
(gdb) info locals
No locals.
```

This issue is particularly annoying because it removes arguments from stack traces.

The DWARF for the inlined function looks like this:

```
< 2><0x00002132 GOFF=0x00002132>      DW_TAG_subprogram
                                        DW_AT_linkage_name          _ZN3tmp6square17hc507052ff3d2a488E
                                        DW_AT_name                  square
                                        DW_AT_decl_file             0x0000000f /ephemeral/tmp/src/main.rs
                                        DW_AT_decl_line             0x00000004
                                        DW_AT_type                  0x00001a56<.debug_info+0x00001a56>
                                        DW_AT_inline                DW_INL_inlined
< 3><0x00002142 GOFF=0x00002142>        DW_TAG_lexical_block
< 4><0x00002143 GOFF=0x00002143>          DW_TAG_formal_parameter
                                            DW_AT_name                  n
                                            DW_AT_decl_file             0x0000000f /ephemeral/tmp/src/main.rs
                                            DW_AT_decl_line             0x00000004
                                            DW_AT_type                  0x00001a56<.debug_info+0x00001a56>
< 4><0x0000214e GOFF=0x0000214e>          DW_TAG_null
< 3><0x0000214f GOFF=0x0000214f>        DW_TAG_null
```

That DW_TAG_lexical_block inhibits every debugger I've tested from recognizing 'n' as a parameter.

This patch removes the additional lexical scope. Parameters can be easily deduplicated by a tuple of their scope and the argument index, at the trivial cost of taking a Hash + Eq bound on DIScope.
2024-08-15 11:42:15 +00:00
.cargo fix: Fix generated markers not being patchable in package.json 2024-06-08 12:54:43 +02:00
.github Only keep lib/ in publish-libs 2024-08-12 13:45:38 +03:00
.vscode feat: use vscode log format for client logs 2024-07-27 21:43:35 -07:00
assets Automatically change text color in logo based on dark mode 2022-03-06 23:06:53 +11:00
bench_data Spelling 2023-04-19 09:45:55 -04:00
crates Merge from rust-lang/rust 2024-08-13 17:58:52 +03:00
docs internal: Reply to requests with defaults when vfs is still loading 2024-08-12 12:05:15 +02:00
editors/code Allow rust-project.json to be hidden 2024-08-07 03:27:03 +02:00
lib Use crossbeam-channel from the workspace 2024-08-09 23:48:03 +02:00
xtask Allow new license combination 2024-08-12 12:51:47 +02:00
.editorconfig add max_line_length to .editorconfig 2024-01-20 17:14:00 +03:00
.git-blame-ignore-revs Show workspace info in the status bar 2024-04-26 11:28:33 +02:00
.gitattributes Fix .gitattributes for test_data 2022-07-24 14:05:35 +02:00
.gitignore internal: add "Shuffle Crate Graph" command 2021-12-07 16:37:19 +01:00
.typos.toml Implement rough symbol interning infra 2024-07-12 16:01:47 +02:00
Cargo.lock Bump rustc_pattern_analysis 2024-08-13 23:15:37 +09:00
Cargo.toml Bump rustc_pattern_analysis 2024-08-13 23:15:37 +09:00
clippy.toml Lint debug prints and disallowed types with clippy 2024-02-01 17:57:27 +01:00
CONTRIBUTING.md Add CONTRIBUTING.md 2024-04-18 10:24:40 +02:00
LICENSE-APACHE Licenses 2018-01-10 22:47:04 +03:00
LICENSE-MIT Licenses 2018-01-10 22:47:04 +03:00
PRIVACY.md Update privacy note 2021-12-23 14:04:15 +02:00
README.md Add CONTRIBUTING.md 2024-04-18 10:24:40 +02:00
rust-bors.toml Prepare for rust-bors 2023-10-05 15:26:09 +03:00
rust-version Preparing for merge from rust-lang/rust 2024-08-13 17:56:37 +03:00
rustfmt.toml Shuffle hir-expand things around 2024-01-26 19:28:39 +01:00
triagebot.toml Update triagebot.toml 2024-06-27 10:32:13 +02:00

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rust-analyzer is a modular compiler frontend for the Rust language. It is a part of a larger rls-2.0 effort to create excellent IDE support for Rust.

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