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Suggest the use of impl Trait in function parameter only

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Currently in case of a Trait object in closure parameter, the compiler
suggests either to use a reference, which is correct or to use an
`impl Trait` which is not. Do not emit this suggestion when the parameter
is part of a closure.
This commit is contained in:
Romain Perier 2025-03-26 15:49:42 +01:00
parent c1b8b7e86f
commit 8b6ff4a378
3 changed files with 38 additions and 6 deletions
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23
compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
View file

@ -3018,12 +3018,23 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
[] => span_bug!(ty.span, "trait object with no traits: {ty:?}"),
};
let needs_parens = traits.len() != 1;
err.span_suggestion_verbose(
span,
"you can use `impl Trait` as the argument type",
"impl ",
Applicability::MaybeIncorrect,
);
// Don't recommend impl Trait as a closure argument
if let Some(hir_id) = hir_id
&& matches!(
self.tcx.parent_hir_node(hir_id),
hir::Node::Item(hir::Item {
kind: hir::ItemKind::Fn { .. },
..
})
)
{
err.span_suggestion_verbose(
span,
"you can use `impl Trait` as the argument type",
"impl ",
Applicability::MaybeIncorrect,
);
}
let sugg = if !needs_parens {
vec![(span.shrink_to_lo(), format!("&{kw}"))]
} else {