diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs index e495bdbf7825c..bfab009a7e35c 100644 --- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs +++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs @@ -920,11 +920,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { // T: Trait // so it seems ok if we (conservatively) fail to accept that `Unsize` // obligation above. Should be possible to extend this in the future. - let Some(source) = obligation.self_ty().no_bound_vars() else { + let Some(trait_pred) = obligation.predicate.no_bound_vars() else { // Don't add any candidates if there are bound regions. return; }; - let target = obligation.predicate.skip_binder().trait_ref.args.type_at(1); + let source = trait_pred.self_ty(); + let target = trait_pred.trait_ref.args.type_at(1); debug!(?source, ?target, "assemble_candidates_for_unsizing"); diff --git a/tests/ui/traits/unsize-goal-escaping-bounds.current.stderr b/tests/ui/traits/unsize-goal-escaping-bounds.current.stderr new file mode 100644 index 0000000000000..e63a0bf50b7aa --- /dev/null +++ b/tests/ui/traits/unsize-goal-escaping-bounds.current.stderr @@ -0,0 +1,19 @@ +error[E0277]: the trait bound `for<'a> (): Unsize<(dyn Trait + 'a)>` is not satisfied + --> $DIR/unsize-goal-escaping-bounds.rs:20:5 + | +LL | foo(); + | ^^^^^ the trait `for<'a> Unsize<(dyn Trait + 'a)>` is not implemented for `()` + | + = note: all implementations of `Unsize` are provided automatically by the compiler, see for more information +note: required by a bound in `foo` + --> $DIR/unsize-goal-escaping-bounds.rs:15:17 + | +LL | fn foo() + | --- required by a bound in this function +LL | where +LL | for<'a> (): Unsize, + | ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `foo` + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/traits/unsize-goal-escaping-bounds.rs b/tests/ui/traits/unsize-goal-escaping-bounds.rs new file mode 100644 index 0000000000000..fb25f7a423900 --- /dev/null +++ b/tests/ui/traits/unsize-goal-escaping-bounds.rs @@ -0,0 +1,22 @@ +//@ revisions: current next +//@[next] compile-flags: -Znext-solver +//@[next] check-pass +//@ ignore-compare-mode-next-solver (explicit revisions) + +#![feature(unsize)] + +use std::marker::Unsize; + +trait Trait {} +impl Trait for () {} + +fn foo() +where + for<'a> (): Unsize, +{ +} + +fn main() { + foo(); + //[current]~^ ERROR the trait bound `for<'a> (): Unsize<(dyn Trait + 'a)>` is not satisfied +}