Parameter and chaning inlay hints no longer work in attribute proc macros

[ChayimFriedman2]

As @mlesin reported, same problem is showing on latest versions (pre-release RA, vscode nightly) with #[instrument]

Originally posted by @insilications in #14527

[insilications]

Thanks for opening the issue. I think the issue could be more general when it comes to inlay hints. Some minimal reproduction showing how closure capture inlay hints disappear when the #[instrument] attribute macro is present:

Using the latest Rustup nightlies. Happens if I use the rust-analyzer 1.89.0-nightly (bc82152 2025-05-20) binary directly, by using the rust-analyzer.server.path setting, or if I use the included rust-analyzer from the VS Code extension.

VS Code Rust Analyzer version: rust-lang.rust-analyzer-0.4.2468-linux-x64

VS Code:

Version: 1.101.0-insider
Commit: 496ebc4723371f29c9ffa0319dcccb2d7bee7ee0
Date: 2025-05-21T05:04:29.987Z
Electron: 35.4.0
ElectronBuildId: 11602177
Chromium: 134.0.6998.205
Node.js: 22.15.0
V8: 13.4.114.21-electron.0
OS: Linux x64 6.5.3-1358.native

Minimal reproduction:

#[tracing::instrument]
fn my_function() {
    let t = "Hello, world!";
    spawn(move || {
        println!("Function executed: {t}");
    });
}

fn spawn(f: impl FnOnce()) {
    f();
}

Without #[tracing::instrument]:

With #[tracing::instrument]:

[insilications]

If you need any extra logs/traces, please tell me how to enable such extra logs/traces from RA and its LSP.

[ChayimFriedman2]

Yes, they all have the same reason. I'm diagnosing it now.

[insilications]

I tried https://github.com/rust-lang/rust-analyzer/releases/tag/nightly with the minimally reproducible example and the closure capture inlay hints are still gone. No errors in rust-analyzer extension and rust-analyzer Language Server...

[Veykril]

The fix in #19839 is on the proc-macro server side. So you won't be able to observe it until its synced back to rust-lang/rust and published as the corresponding rustup componenet, or you build that component manually and point rust-analyzer to use the self-build one.

[insilications]

@Veykril thanks for clarifying! I should have looked at which files were changed in the commit 😛

I will build it manually.

[insilications]

For those waiting, it seems that the fix may land in the next nightly and available through rustup.

[ChayimFriedman2]

@insilications Did you verify it works?

Anyway it will only be available for those using nightly toolchain. Those using stable toolchains will have to wait until the next Rust release.

[insilications]

@insilications Did you verify it works?

Anyway it will only be available for those using nightly toolchain. Those using stable toolchains will have to wait until the next Rust release.

I decided to wait for it to drop in the next nightly toolchain in order to test it. Seems like it is very close to bring your changes into it (https://github.com/rust-lang/rust/commits/master/src/tools/rust-analyzer/crates/proc-macro-srv/src). I am being lazy, I could build it manually.

[insilications]

@ChayimFriedman2 It seems it is still happening with the nightly-x86_64-unknown-linux-gnu (2025-06-07) toolchain.

VS Code Rust Analyzer version: rust-lang.rust-analyzer-0.4.2488-linux-x64

VS Code:

Version: 1.101.0-insider
Commit: f832c6b59a2ed11890f4988a29e85658b092a69a
Date: 2025-06-06T20:43:03.362Z
Electron: 35.5.1
ElectronBuildId: 11708675
Chromium: 134.0.6998.205
Node.js: 22.15.1
V8: 13.4.114.21-electron.0
OS: Linux x64 6.5.3-1358.native

When removing #[tracing::instrument] or using the ignore options to ignore proc-macro analysis of tracing::instrument in the proc-macro srv:

  "rust-analyzer.procMacro.ignored": {
    "tracing-attributes": ["instrument"]
  }

#[tracing::instrument]
fn my_function() {
    let t = "Hello, world!";
    spawn(move || {
        println!("Function executed: {t}");
    });
}

fn spawn(f: impl FnOnce()) {
    f();
}

It shows the correct closure capture inlay hints:

When I remove the ignore options, the closure capture inlay hints disappear:

[ChayimFriedman2]

@insilications I didn't check closure capture hints when analyzing this, and in fact now when analyzing them I see they will indeed not work (they don't descend into attributes). Can you check with chaining and parameter hints?

[insilications]

@ChayimFriedman2