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Rollup merge of #140568 - moxian:reg-140545, r=compiler-errors

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Add regression test for #140545

Closes #140545

I am not very knowledgable about the typesystem internals, so I couldn't come up with a good name for the test. But I'm happy to move it to a more appropriate place if there is one (`tests/ui/impl-trait/non-defining-uses` maybe?)

r? types (or reroll as appropriate if this is not actually a T-types issue; i'm clueless)
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Matthias Krüger 2025-05-03 08:45:04 +02:00 • committed by GitHub
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12
tests/ui/impl-trait/non-defining-uses/double-wrap-with-defining-use.rs Normal file
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// Regression test for ICE from issue #140545
// The error message is confusing and wrong, but that's a different problem (#139350)
//@ edition:2018
trait Foo {}
fn a(x: impl Foo) -> impl Foo {
if true { x } else { a(a(x)) }
//~^ ERROR: expected generic type parameter, found `impl Foo` [E0792]
//~| ERROR: type parameter `impl Foo` is part of concrete type but not used in parameter list for the `impl Trait` type alias
}
fn main(){}

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tests/ui/impl-trait/non-defining-uses/double-wrap-with-defining-use.stderr Normal file
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error[E0792]: expected generic type parameter, found `impl Foo`
--> $DIR/double-wrap-with-defining-use.rs:7:26
|
LL | fn a(x: impl Foo) -> impl Foo {
| -------- this generic parameter must be used with a generic type parameter
LL | if true { x } else { a(a(x)) }
| ^^^^^^^
error: type parameter `impl Foo` is part of concrete type but not used in parameter list for the `impl Trait` type alias
--> $DIR/double-wrap-with-defining-use.rs:7:26
|
LL | if true { x } else { a(a(x)) }
| ^^^^^^^
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0792`.