bjoernager/rust
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unused-lifetimes: don't warn about lifetimes originating from expanded code

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previously, we would warn like this:

````
warning: lifetime parameter `'s` never used
 --> /tmp/unusedlif/code.rs:6:62
  |
5 | #[derive(Clone)]
  |          - help: elide the unused lifetime
6 | struct ShimMethod4<T: Trait2 + 'static>(pub &'static dyn for<'s> Fn(&'s mut T::As));
  |                                                              ^^
  |
  = note: requested on the command line with `-W unused-lifetimes`
````

Fixes #104432
This commit is contained in:
Matthias Krüger 2023-02-03 20:48:25 +01:00
parent 9545094994
commit a3637032db
2 changed files with 28 additions and 12 deletions
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28
compiler/rustc_resolve/src/late/diagnostics.rs
View file

@ -2244,19 +2244,23 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
}
None => {
debug!(?param.ident, ?param.ident.span);
let deletion_span = deletion_span();
self.r.lint_buffer.buffer_lint_with_diagnostic(
lint::builtin::UNUSED_LIFETIMES,
param.id,
param.ident.span,
&format!("lifetime parameter `{}` never used", param.ident),
lint::BuiltinLintDiagnostics::SingleUseLifetime {
param_span: param.ident.span,
use_span: None,
deletion_span,
},
);
// the give lifetime originates from expanded code so we won't be able to remove it #104432
let lifetime_only_in_expanded_code =
deletion_span.map(|sp| sp.in_derive_expansion()).unwrap_or(true);
if !lifetime_only_in_expanded_code {
self.r.lint_buffer.buffer_lint_with_diagnostic(
lint::builtin::UNUSED_LIFETIMES,
param.id,
param.ident.span,
&format!("lifetime parameter `{}` never used", param.ident),
lint::BuiltinLintDiagnostics::SingleUseLifetime {
param_span: param.ident.span,
use_span: None,
deletion_span,
},
);
}
}
}
}