diff options
3 files changed, 48 insertions, 1 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs index 525b3105538..14c5b83c6ca 100644 --- a/compiler/rustc_trait_selection/src/solve/project_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs @@ -174,7 +174,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { goal.predicate.def_id(), impl_def_id )? else { - return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes); + return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS); }; if !assoc_def.item.defaultness(tcx).has_value() { diff --git a/tests/ui/traits/new-solver/specialization-unconstrained.rs b/tests/ui/traits/new-solver/specialization-unconstrained.rs new file mode 100644 index 00000000000..02150689ee5 --- /dev/null +++ b/tests/ui/traits/new-solver/specialization-unconstrained.rs @@ -0,0 +1,22 @@ +// compile-flags: -Ztrait-solver=next + +#![feature(specialization)] +//~^ WARN the feature `specialization` is incomplete + +// Do not treat the RHS of a projection-goal as an unconstrained `Certainty::Yes` response +// if the impl is still further specializable. + +trait Default { + type Id; +} + +impl<T> Default for T { + default type Id = T; +} + +fn test<T: Default<Id = U>, U>() {} + +fn main() { + test::<u32, ()>(); + //~^ ERROR cannot satisfy `<u32 as Default>::Id == ()` +} diff --git a/tests/ui/traits/new-solver/specialization-unconstrained.stderr b/tests/ui/traits/new-solver/specialization-unconstrained.stderr new file mode 100644 index 00000000000..910925cbaeb --- /dev/null +++ b/tests/ui/traits/new-solver/specialization-unconstrained.stderr @@ -0,0 +1,25 @@ +warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes + --> $DIR/specialization-unconstrained.rs:3:12 + | +LL | #![feature(specialization)] + | ^^^^^^^^^^^^^^ + | + = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information + = help: consider using `min_specialization` instead, which is more stable and complete + = note: `#[warn(incomplete_features)]` on by default + +error[E0284]: type annotations needed: cannot satisfy `<u32 as Default>::Id == ()` + --> $DIR/specialization-unconstrained.rs:20:5 + | +LL | test::<u32, ()>(); + | ^^^^^^^^^^^^^^^ cannot satisfy `<u32 as Default>::Id == ()` + | +note: required by a bound in `test` + --> $DIR/specialization-unconstrained.rs:17:20 + | +LL | fn test<T: Default<Id = U>, U>() {} + | ^^^^^^ required by this bound in `test` + +error: aborting due to previous error; 1 warning emitted + +For more information about this error, try `rustc --explain E0284`. |