| // run-pass |
| |
| // Check that resolving, in the value namespace, to an `enum` variant |
| // through a type alias is well behaved in the presence of generics. |
| // We check for situations with: |
| // 1. a generic type `Alias<T>`, we can type-apply `Alias` when referring to a variant. |
| // 2. a monotype `AliasFixed` of generic `Enum<T>`, we can refer to variants |
| // and the type-application of `T` in `AliasFixed` is kept. |
| |
| #![allow(irrefutable_let_patterns)] |
| |
| enum Enum<T> { TSVariant(T), SVariant { _v: T }, UVariant } |
| type Alias<T> = Enum<T>; |
| type AliasFixed = Enum<()>; |
| |
| macro_rules! is_variant { |
| (TSVariant, $expr:expr) => (is_variant!(@check TSVariant, (_), $expr)); |
| (SVariant, $expr:expr) => (is_variant!(@check SVariant, { _v: _ }, $expr)); |
| (UVariant, $expr:expr) => (is_variant!(@check UVariant, {}, $expr)); |
| (@check $variant:ident, $matcher:tt, $expr:expr) => ( |
| assert!(if let Enum::$variant::<()> $matcher = $expr { true } else { false }, |
| "expr does not have correct type"); |
| ); |
| } |
| |
| fn main() { |
| // Tuple struct variant |
| |
| is_variant!(TSVariant, Enum::TSVariant(())); |
| is_variant!(TSVariant, Enum::TSVariant::<()>(())); |
| is_variant!(TSVariant, Enum::<()>::TSVariant(())); |
| |
| is_variant!(TSVariant, Alias::TSVariant(())); |
| is_variant!(TSVariant, Alias::<()>::TSVariant(())); |
| |
| is_variant!(TSVariant, AliasFixed::TSVariant(())); |
| |
| // Struct variant |
| |
| is_variant!(SVariant, Enum::SVariant { _v: () }); |
| is_variant!(SVariant, Enum::SVariant::<()> { _v: () }); |
| is_variant!(SVariant, Enum::<()>::SVariant { _v: () }); |
| |
| is_variant!(SVariant, Alias::SVariant { _v: () }); |
| is_variant!(SVariant, Alias::<()>::SVariant { _v: () }); |
| |
| is_variant!(SVariant, AliasFixed::SVariant { _v: () }); |
| |
| // Unit variant |
| |
| is_variant!(UVariant, Enum::UVariant); |
| is_variant!(UVariant, Enum::UVariant::<()>); |
| is_variant!(UVariant, Enum::<()>::UVariant); |
| |
| is_variant!(UVariant, Alias::UVariant); |
| is_variant!(UVariant, Alias::<()>::UVariant); |
| |
| is_variant!(UVariant, AliasFixed::UVariant); |
| } |