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builtin dyn impl no guide inference

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lcnr 2025-05-21 14:36:50 +00:00
parent 2f176126aa
commit bde63bb251
4 changed files with 62 additions and 1 deletions
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16
tests/ui/traits/object/no-incomplete-inference.current.stderr Normal file
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error[E0283]: type annotations needed
--> $DIR/no-incomplete-inference.rs:16:5
|
LL | impls_equals::<dyn Equals<u32>, _>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `U` declared on the function `impls_equals`
|
= note: cannot satisfy `dyn Equals<u32>: Equals<_>`
note: required by a bound in `impls_equals`
--> $DIR/no-incomplete-inference.rs:13:20
|
LL | fn impls_equals<T: Equals<U> + ?Sized, U: ?Sized>() {}
| ^^^^^^^^^ required by this bound in `impls_equals`
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0283`.

16
tests/ui/traits/object/no-incomplete-inference.next.stderr Normal file
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error[E0283]: type annotations needed
--> $DIR/no-incomplete-inference.rs:16:5
|
LL | impls_equals::<dyn Equals<u32>, _>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `U` declared on the function `impls_equals`
|
= note: cannot satisfy `dyn Equals<u32>: Equals<_>`
note: required by a bound in `impls_equals`
--> $DIR/no-incomplete-inference.rs:13:20
|
LL | fn impls_equals<T: Equals<U> + ?Sized, U: ?Sized>() {}
| ^^^^^^^^^ required by this bound in `impls_equals`
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0283`.

18
tests/ui/traits/object/no-incomplete-inference.rs Normal file
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//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[next] compile-flags: -Znext-solver
// Make sure that having an applicable user-written
// and builtin impl is ambiguous.
trait Equals<T: ?Sized> {}
impl<T: ?Sized> Equals<T> for T {}
fn impls_equals<T: Equals<U> + ?Sized, U: ?Sized>() {}
fn main() {
impls_equals::<dyn Equals<u32>, _>();
//~^ ERROR type annotations needed
}