diff options
| -rw-r--r-- | src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.rs | 20 | ||||
| -rw-r--r-- | src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.stderr | 6 |
2 files changed, 23 insertions, 3 deletions
diff --git a/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.rs b/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.rs index 229046cc5cd..7f69590400b 100644 --- a/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.rs +++ b/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.rs @@ -1,3 +1,23 @@ +// Check that a projection `Self::V` in a trait implementation, +// with an associated type named `V`, for an `enum` with a variant named `V`, +// results in triggering the deny-by-default lint `ambiguous_associated_items`. +// The lint suggests that qualified syntax should be used instead. +// That is, the user would write `<Self as Tr>::V`. +// +// The rationale for this is that while `enum` variants do currently +// not exist in the type namespace but solely in the value namespace, +// RFC #2593 "Enum variant types", would add enum variants to the type namespace. +// However, currently `enum` variants are resolved with high priority as +// they are resolved as inherent associated items. +// Should #2953 therefore be implemented, `Self::V` would suddenly switch +// from referring to the associated type `V` instead of the variant `V`. +// The lint exists to keep us forward compatible with #2593. +// +// As a closing note, provided that #2933 was implemented and +// if `enum` variants were given lower priority than associated types, +// it would be impossible to refer to the `enum` variant `V` whereas +// the associated type could be referred to with qualified syntax as seen above. + enum E { V } diff --git a/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.stderr b/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.stderr index df75cbc6b2b..05512ed2bca 100644 --- a/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.stderr +++ b/src/test/ui/type-alias-enum-variants/type-alias-enum-variants-priority.stderr @@ -1,5 +1,5 @@ error: ambiguous associated item - --> $DIR/type-alias-enum-variants-priority.rs:12:15 + --> $DIR/type-alias-enum-variants-priority.rs:32:15 | LL | fn f() -> Self::V { 0 } | ^^^^^^^ help: use fully-qualified syntax: `<E as Trait>::V` @@ -8,12 +8,12 @@ LL | fn f() -> Self::V { 0 } = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! = note: for more information, see issue #57644 <https://github.com/rust-lang/rust/issues/57644> note: `V` could refer to variant defined here - --> $DIR/type-alias-enum-variants-priority.rs:2:5 + --> $DIR/type-alias-enum-variants-priority.rs:22:5 | LL | V | ^ note: `V` could also refer to associated type defined here - --> $DIR/type-alias-enum-variants-priority.rs:6:5 + --> $DIR/type-alias-enum-variants-priority.rs:26:5 | LL | type V; | ^^^^^^^ |