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