45 lines
1.1 KiB
Rust
45 lines
1.1 KiB
Rust
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// ICE unexpected inference var
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// issue: rust-lang/rust#116599
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//@ check-pass
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pub trait EvaluateConstMethods {
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type Trait: TraitWithConstMethods;
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/// **This block breaks**
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const DATA_3: Data3 = {
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<<<Self::Trait as TraitWithConstMethods>::Method2 as ConstFn<_, _>>::Body<
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<<Self::Trait as TraitWithConstMethods>::Method1 as ConstFn<_, _>>::Body<ContainsData1>,
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> as Contains<_>>::ITEM
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};
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}
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pub trait TraitWithConstMethods {
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/// "const trait method" of signature `fn(Data1) -> Data2`
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type Method1: ConstFn<Data1, Data2>;
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/// "const trait method" of signature `fn(Data2) -> Data3`
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type Method2: ConstFn<Data2, Data3>;
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}
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/// A trait which tries to implement const methods in traits
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pub trait ConstFn<Arg, Ret> {
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type Body<T: Contains<Arg>>: Contains<Ret>;
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}
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/// A ZST which represents / "contains" a const value which can be pass to a [`ConstFn`]
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pub trait Contains<T> {
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const ITEM: T;
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}
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pub struct ContainsData1;
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impl Contains<Data1> for ContainsData1 {
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const ITEM: Data1 = Data1 {};
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}
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// Arbitrary data
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pub struct Data1 {}
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pub struct Data2 {}
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pub struct Data3 {}
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pub fn main() {}
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