| //@ compile-flags: -Znext-solver |
| |
| // When we're solving `<T as Foo>::Assoc = i32`, we actually first solve |
| // `<T as Foo>::Assoc = ?1t`, then unify `?1t` with `i32`. That goal |
| // with the inference variable is ambiguous when there are >1 param-env |
| // candidates. |
| |
| // We don't unify the RHS of a projection goal eagerly when solving, both |
| // for caching reasons and partly to make sure that we don't make the new |
| // trait solver smarter than it should be. |
| |
| // This is (as far as I can tell) a forwards-compatible decision, but if you |
| // make this test go from fail to pass, be sure you understand the implications! |
| |
| trait Foo { |
| type Assoc; |
| } |
| |
| trait Bar {} |
| |
| impl<T> Bar for T where T: Foo<Assoc = i32> {} |
| |
| fn needs_bar<T: Bar>() {} |
| |
| fn foo<T: Foo<Assoc = i32> + Foo<Assoc = u32>>() { |
| needs_bar::<T>(); |
| //~^ ERROR type annotations needed: cannot normalize |
| } |
| |
| fn main() {} |
