diff options
Diffstat (limited to 'tests/ui/traits/trait-upcasting/inference-behavior-change-deref.rs')
-rw-r--r-- | tests/ui/traits/trait-upcasting/inference-behavior-change-deref.rs | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/tests/ui/traits/trait-upcasting/inference-behavior-change-deref.rs b/tests/ui/traits/trait-upcasting/inference-behavior-change-deref.rs new file mode 100644 index 000000000..79fb643ea --- /dev/null +++ b/tests/ui/traits/trait-upcasting/inference-behavior-change-deref.rs @@ -0,0 +1,36 @@ +#![deny(deref_into_dyn_supertrait)] +#![feature(trait_upcasting)] // remove this and the test compiles + +use std::ops::Deref; + +trait Bar<T> {} +impl<T, U> Bar<U> for T {} + +trait Foo: Bar<i32> { + fn as_dyn_bar_u32<'a>(&self) -> &(dyn Bar<u32> + 'a); +} + +impl Foo for () { + fn as_dyn_bar_u32<'a>(&self) -> &(dyn Bar<u32> + 'a) { + self + } +} + +impl<'a> Deref for dyn Foo + 'a { + type Target = dyn Bar<u32> + 'a; + + fn deref(&self) -> &Self::Target { + self.as_dyn_bar_u32() + } +} + +fn take_dyn<T>(x: &dyn Bar<T>) -> T { + todo!() +} + +fn main() { + let x: &dyn Foo = &(); + let y = take_dyn(x); + let z: u32 = y; + //~^ ERROR mismatched types +} |