rust-lang / rust-lang/rust-analyzer
Useless diagnostics from procmacro expansion
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Description
rust-analyzer version: rust-analyzer version: 0.4.1834-standalone (c48f14553 2024-02-07)
rustc version: rustc 1.75.0 (82e1608df 2023-12-21)
Open Zed, wait for r-a to load it and produce diagnostics in this file:
https://github.com/zed-industries/zed/blob/bde509fa749da60beb4ac378afd3ade15297bb91/crates/editor/src/display_map.rs#L1685
or
https://github.com/zed-industries/zed/blob/bde509fa749da60beb4ac378afd3ade15297bb91/crates/multi_buffer/src/multi_buffer.rs#L4764
this diagnostic is very volatile, but usually appears around those files, sometimes producing dozens of errors, sometimes a couple.
Inside #[gpui::test] macro expansion there's indeed a let mut ... binding that does not need to be mutable, but
- rustc/cargo does not emit such warnings
- what the end procmacro user is supposed to do about it?
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the diagnostics in Zed at crates/editor/src/display_map.rs:1685 or crates/multi_buffer/src/multi_buffer.rs:4764 using the reported rust-analyzer and rustc versions. Inspect how the #[gpui::test] proc-macro expansion produces the unused-mut warning and compare it with rustc/cargo diagnostics. Done means the expansion no longer exposes this useless diagnostic to the end user.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 30/100