RA not working when using `#[tonic::async_trait]`

[ncs-pl]

This is a serious regression in nightly and it's important to fix it before the next release.
@matklad, please take a look.

Hi. For more than two hours, I tried debugging my VSCode since Rust-Analyzer was not working while I was implementing a gRPC Service using tonic.
By not working I mean that I do not get any autocompletion/IntelliSense for variables, structs, functions...
However, I still get errors reported by cargo check.

I figured out that when I was implementing methods in #[tonic::async_trait], Rust-Analyzer was not working, but when I remove #[tonic::async_trait] Rust-Analyzer is working.

I chose the Critical Nightly Regression since Rust-Analyzer is unusable in #[tonic::async_trait] and working in #[tonic::async_trait]-like traits is pretty common. (Sorry if it was not the good choice)

Versions

Code-Insider

1.61.0-insider
87260247dc7b912db6e6a21a366e6f50dca759ba
x64

In WSL2 on Windows 10

[matklad]

To clarify, is is the case that every version of rust-analyzer isn't working for you? Or is there some version that used to work, and it's just the latest nightly that's broken?

[ncs-pl]

I had the same problem yesterday. Since I got a new RA update today and it is also not working, I guess the problem exists in multiple nightly versions.

[matklad]

Ok, so my understanding is that is not a regression than -- it's just that this has never fully worked in the first place. The current state is:

• you can set "rust-analyzer.experimental.procAttrMacros": true, which will enable better completions outside of proc macroed code, at the cost of completely disabling completion inside, eg, impls annotated with #[async_trait]
• you can set "rust-analyzer.experimental.procAttrMacros": false, then you'll have partial completions both inside and outside of the macros
• you can try feat: Speculatively expand attributes in completions #10126 -- it is the next step in us fully supporting the feature. Locally it doesn't work for the example from async_trait though (cc @Veykril).

We understand that fully supporting async_trait and the like is important for adequate UX in may cases -- it's just that procedural macros are in general a pain in the back to support in an IDE. We are working on it, but it's hard :)

[ncs-pl]

Thanks for the response!
I totally understand it is a pain and I wish good lucks to you guys. I disabled "rust-analyzer.experimental.procAttrMacros": false for now and it work as expected for now.