diff options
Diffstat (limited to 'tests/ui/associated-types/defaults-in-other-trait-items.rs')
-rw-r--r-- | tests/ui/associated-types/defaults-in-other-trait-items.rs | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/tests/ui/associated-types/defaults-in-other-trait-items.rs b/tests/ui/associated-types/defaults-in-other-trait-items.rs new file mode 100644 index 000000000..505751969 --- /dev/null +++ b/tests/ui/associated-types/defaults-in-other-trait-items.rs @@ -0,0 +1,47 @@ +#![feature(associated_type_defaults)] + +// Associated type defaults may not be assumed inside the trait defining them. +// ie. they only resolve to `<Self as Tr>::A`, not the actual type `()` +trait Tr { + type A = (); //~ NOTE associated type defaults can't be assumed inside the trait defining them + + fn f(p: Self::A) { + let () = p; + //~^ ERROR mismatched types + //~| NOTE expected associated type, found `()` + //~| NOTE expected associated type `<Self as Tr>::A` + //~| NOTE this expression has type `<Self as Tr>::A` + } +} + +// An impl that doesn't override the type *can* assume the default. +impl Tr for () { + fn f(p: Self::A) { + let () = p; + } +} + +impl Tr for u8 { + type A = (); + + fn f(p: Self::A) { + let () = p; + } +} + +trait AssocConst { + type Ty = u8; //~ NOTE associated type defaults can't be assumed inside the trait defining them + + // Assoc. consts also cannot assume that default types hold + const C: Self::Ty = 0u8; + //~^ ERROR mismatched types + //~| NOTE expected associated type, found `u8` + //~| NOTE expected associated type `<Self as AssocConst>::Ty` +} + +// An impl can, however +impl AssocConst for () { + const C: Self::Ty = 0u8; +} + +fn main() {} |