3 // Check that resolving, in the value namespace, to an `enum` variant
4 // through a type alias is well behaved in the presence of generics.
5 // We check for situations with:
6 // 1. a generic type `Alias<T>`, we can type-apply `Alias` when referring to a variant.
7 // 2. a monotype `AliasFixed` of generic `Enum<T>`, we can refer to variants
8 // and the type-application of `T` in `AliasFixed` is kept.
10 #![allow(irrefutable_let_patterns)]
12 enum Enum<T> { TSVariant(#[allow(unused_tuple_struct_fields)] T), SVariant { _v: T }, UVariant }
13 type Alias<T> = Enum<T>;
14 type AliasFixed = Enum<()>;
16 macro_rules! is_variant {
17 (TSVariant, $expr:expr) => (is_variant!(@check TSVariant, (_), $expr));
18 (SVariant, $expr:expr) => (is_variant!(@check SVariant, { _v: _ }, $expr));
19 (UVariant, $expr:expr) => (is_variant!(@check UVariant, {}, $expr));
20 (@check $variant:ident, $matcher:tt, $expr:expr) => (
21 assert!(if let Enum::$variant::<()> $matcher = $expr { true } else { false },
22 "expr does not have correct type");
27 // Tuple struct variant
29 is_variant!(TSVariant, Enum::TSVariant(()));
30 is_variant!(TSVariant, Enum::TSVariant::<()>(()));
31 is_variant!(TSVariant, Enum::<()>::TSVariant(()));
33 is_variant!(TSVariant, Alias::TSVariant(()));
34 is_variant!(TSVariant, Alias::<()>::TSVariant(()));
36 is_variant!(TSVariant, AliasFixed::TSVariant(()));
40 is_variant!(SVariant, Enum::SVariant { _v: () });
41 is_variant!(SVariant, Enum::SVariant::<()> { _v: () });
42 is_variant!(SVariant, Enum::<()>::SVariant { _v: () });
44 is_variant!(SVariant, Alias::SVariant { _v: () });
45 is_variant!(SVariant, Alias::<()>::SVariant { _v: () });
47 is_variant!(SVariant, AliasFixed::SVariant { _v: () });
51 is_variant!(UVariant, Enum::UVariant);
52 is_variant!(UVariant, Enum::UVariant::<()>);
53 is_variant!(UVariant, Enum::<()>::UVariant);
55 is_variant!(UVariant, Alias::UVariant);
56 is_variant!(UVariant, Alias::<()>::UVariant);
58 is_variant!(UVariant, AliasFixed::UVariant);