mirror of https://github.com/rust-lang/rust
59 lines
1.3 KiB
Rust
59 lines
1.3 KiB
Rust
// Test that we get implied bounds from complex projections after normalization.
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//@ check-pass
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// implementations wil ensure that
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// WF(<T as Combine<'a>>::Ty) implies T: 'a
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trait Combine<'a> {
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type Ty;
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}
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impl<'a, T: 'a> Combine<'a> for Box<T> {
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type Ty = &'a T;
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}
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// ======= Wrappers ======
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// normalizes to a projection
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struct WrapA<T>(T);
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impl<'a, T> Combine<'a> for WrapA<T>
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where
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T: Combine<'a>,
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{
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type Ty = T::Ty;
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}
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// <WrapB<T> as Combine<'a>>::Ty normalizes to a type variable ?X
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// with constraint `<T as Combine<'a>>::Ty == ?X`
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struct WrapB<T>(T);
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impl<'a, X, T> Combine<'a> for WrapB<T>
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where
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T: Combine<'a, Ty = X>,
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{
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type Ty = X;
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}
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// <WrapC<T> as Combine<'a>>::Ty normalizes to `&'a &'?x ()`
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// with constraint `<T as Combine<'a>>::Ty == &'a &'?x ()`
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struct WrapC<T>(T);
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impl<'a, 'x: 'a, T> Combine<'a> for WrapC<T>
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where
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T: Combine<'a, Ty = &'a &'x ()>,
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{
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type Ty = &'a &'x ();
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}
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//==== Test implied bounds ======
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fn test_wrap<'a, 'b, 'c1, 'c2, A, B>(
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_: <WrapA<Box<A>> as Combine<'a>>::Ty, // normalized: &'a A
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_: <WrapB<Box<B>> as Combine<'b>>::Ty, // normalized: &'b B
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_: <WrapC<Box<&'c1 ()>> as Combine<'c2>>::Ty, // normalized: &'c2 &'c1 ()
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) {
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None::<&'a A>;
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None::<&'b B>;
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None::<&'c2 &'c1 ()>;
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}
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fn main() {}
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