1 // Issue 52985: user code provides no use case that allows a type alias `impl Trait`
2 // We now emit a 'unconstrained opaque type' error
4 #![feature(type_alias_impl_trait)]
6 type Foo = impl Copy; //~ unconstrained opaque type
8 // make compiler happy about using 'Foo'
9 fn bar(x: Foo) -> Foo {
14 let _: Foo = std::mem::transmute(0u8);