rust-lang / rust-lang/rust-analyzer
Wrong inferred `impl FnMut()`
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Description
rust-analyzer version: 0.3.1748-standalone (237712fa3 2023-11-26)
rustc version: 1.74.0
rust-analyzer infers wrong type for closure, rustc says it only implements FnOnce, but RA shows impl FnMut
struct Int(i32);
impl Int {
fn change(&mut self) {
self.0 += 1;
}
}
let mut int = Int(0);
// RA: impl FnMut()
let foo = move || {
async move {
int.change();
};
};
fn is_it_fn_mut(_val: impl FnMut()) {}
is_it_fn_mut(foo); // rustc error
rustc error:
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- Read the whole issue, then the project's contributing guide.
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Research direction
Start by reproducing the minimal closure example in the issue with the specified rust-analyzer and rustc versions, then compare the inferred impl FnMut() with rustc's FnOnce result. The issue is done when rust-analyzer reports the closure's inferred trait consistently with rustc for this case.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100