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// 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(#[allow(unused_tuple_struct_fields)] 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);
}
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