diff options
Diffstat (limited to 'tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs')
-rw-r--r-- | tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs b/tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs new file mode 100644 index 000000000..6f8164f3a --- /dev/null +++ b/tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs @@ -0,0 +1,22 @@ +// compile-flags: -Ztrait-solver=next +// check-pass + +trait Foo {} + +impl<T> Foo for T {} + +trait Bar {} + +struct Wrapper<'a, T>(&'a T); + +impl<'a, T> Bar for Wrapper<'a, T> where &'a T: Foo {} +// We need to satisfy `&'a T: Foo` when checking that this impl is WF +// that can either be satisfied via the param-env, or via an impl. +// +// When satisfied via the param-env, since each lifetime is canonicalized +// separately, we end up getting extra region constraints. +// +// However, when satisfied via the impl, there are no region constraints, +// and we can short-circuit a response with no external constraints. + +fn main() {} |