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Add a note when suggesting to use Impl Trait #112088

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0bba4e5
Add a note when suggesting to use Impl Trait
sladyn98 May 29, 2023
f863353
Updated tests
sladyn98 May 30, 2023
c4d04e7
Fix typo
sladyn98 May 30, 2023
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3 changes: 3 additions & 0 deletions compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -856,6 +856,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
format!("impl {}", all_bounds_str),
Applicability::MaybeIncorrect,
);

let ty::Param(found_ty_as_param) = found.kind() else { return };
err.note(format!("the type of `{}` is chosen by the caller and may be a type that is different from `{}`", expected_ty_as_param.name, found_ty_as_param.name));
}
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@compiler-errors Here found_ty_as_param should return the parameter found right, or am I understanding something wrong

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You don't need found_ty_as_param -- the found ty might be any type, and you can just render that to string.

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    err.note(format!("the type of `{}` is chosen by the caller and may be a type that is different from `{}` ", expected_ty_as_param.name, found.to_string()));

Converting found to string still does not return the type expected.


pub(in super::super) fn suggest_missing_break_or_return_expr(
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1 change: 1 addition & 0 deletions tests/ui/return/return-impl-trait-bad.stderr
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Expand Up @@ -53,6 +53,7 @@ LL | "don't suggest this, because the generic param is used in the bound."
|
= note: expected type parameter `T`
found reference `&'static str`
= note: the type of `T` is chosen by the caller and may be a type that is different than `T`
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may be a type that is different than T

Hmm... typo?

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Fixed it

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@compiler-errors compiler-errors May 30, 2023 •
edited
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Sorry, I was not clear with what I meant here.

the type of T is chosen by the caller and may be a type that is different than T

This sentence mentions T twice, which does not make sense. The other type in this error is &'static str, which should be mentioned.


error: aborting due to 4 previous errors

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2 changes: 2 additions & 0 deletions tests/ui/return/return-impl-trait.stderr
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Expand Up @@ -12,6 +12,7 @@ LL | ()
|
= note: expected type parameter `T`
found unit type `()`
= note: the type of `T` is chosen by the caller and may be a type that is different than `T`

error[E0308]: mismatched types
--> $DIR/return-impl-trait.rs:23:5
Expand All @@ -28,6 +29,7 @@ LL | ()
|
= note: expected type parameter `T`
found unit type `()`
= note: the type of `T` is chosen by the caller and may be a type that is different than `T`

error: aborting due to 2 previous errors

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