diff options
4 files changed, 62 insertions, 1 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index 3a2f9e8ca17..1b9b68fa980 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -1919,12 +1919,23 @@ impl<'tcx> SelectionContext<'_, 'tcx> { // impl `impl<T: ?Sized> Any for T { .. }`. This really shouldn't exist but is // necessary due to #57893. We again arbitrarily prefer the applicable candidate // with the lowest index. + // + // We do not want to use these impls to guide inference in case a user-written impl + // may also apply. let object_bound = candidates .iter() .filter_map(|c| if let ObjectCandidate(i) = c.candidate { Some(i) } else { None }) .try_reduce(|c1, c2| if has_non_region_infer { None } else { Some(c1.min(c2)) }); match object_bound { - Some(Some(index)) => return Some(ObjectCandidate(index)), + Some(Some(index)) => { + return if has_non_region_infer + && candidates.iter().any(|c| matches!(c.candidate, ImplCandidate(_))) + { + None + } else { + Some(ObjectCandidate(index)) + }; + } Some(None) => {} None => return None, } diff --git a/tests/ui/traits/object/no-incomplete-inference.current.stderr b/tests/ui/traits/object/no-incomplete-inference.current.stderr new file mode 100644 index 00000000000..3c6b811a49e --- /dev/null +++ b/tests/ui/traits/object/no-incomplete-inference.current.stderr @@ -0,0 +1,16 @@ +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`. diff --git a/tests/ui/traits/object/no-incomplete-inference.next.stderr b/tests/ui/traits/object/no-incomplete-inference.next.stderr new file mode 100644 index 00000000000..3c6b811a49e --- /dev/null +++ b/tests/ui/traits/object/no-incomplete-inference.next.stderr @@ -0,0 +1,16 @@ +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`. diff --git a/tests/ui/traits/object/no-incomplete-inference.rs b/tests/ui/traits/object/no-incomplete-inference.rs new file mode 100644 index 00000000000..9ed8dd6c0b1 --- /dev/null +++ b/tests/ui/traits/object/no-incomplete-inference.rs @@ -0,0 +1,18 @@ +//@ 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 +} |