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Diffstat (limited to '')
-rw-r--r-- | tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs b/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs new file mode 100644 index 000000000..fd5d0e3b1 --- /dev/null +++ b/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs @@ -0,0 +1,45 @@ +// compile-flags: -Ztrait-solver=next + +// check that when computing `alias-eq(<() as Foo<u16, T>>::Assoc, <() as Foo<?0, T>>::Assoc)` +// we do not infer `?0 = u8` via the `for<STOP> (): Foo<u8, STOP>` impl or `?0 = u16` by +// relating substs as either could be a valid solution. + +trait Foo<T, STOP> { + type Assoc; +} + +impl<STOP> Foo<u8, STOP> for () +where + (): Foo<u16, STOP>, +{ + type Assoc = <() as Foo<u16, STOP>>::Assoc; +} + +impl Foo<u16, i8> for () { + type Assoc = u8; +} + +impl Foo<u16, i16> for () { + type Assoc = u16; +} + +fn output<T, U>() -> <() as Foo<T, U>>::Assoc +where + (): Foo<T, U>, +{ + todo!() +} + +fn incomplete<T>() +where + (): Foo<u16, T>, +{ + // `<() as Foo<u16, STOP>>::Assoc == <() as Foo<_, STOP>>::Assoc` + let _: <() as Foo<u16, T>>::Assoc = output::<_, T>(); + //~^ error: type annotations needed + + // let _: <() as Foo<u16, T>>::Assoc = output::<u8, T>(); // OK + // let _: <() as Foo<u16, T>>::Assoc = output::<u16, T>(); // OK +} + +fn main() {} |