74 lines
1.3 KiB
Rust
74 lines
1.3 KiB
Rust
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// build-pass
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#![allow(incomplete_features)]
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#![feature(generic_const_exprs)]
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use std::marker::PhantomData;
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fn main() {
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let x = FooImpl::<BarImpl<1>> { phantom: PhantomData };
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let _ = x.foo::<BarImpl<1>>();
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}
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trait Foo<T>
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where
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T: Bar,
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{
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fn foo<U>(&self)
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where
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T: Operation<U>,
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<T as Operation<U>>::Output: Bar;
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}
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struct FooImpl<T>
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where
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T: Bar,
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{
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phantom: PhantomData<T>,
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}
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impl<T> Foo<T> for FooImpl<T>
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where
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T: Bar,
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{
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fn foo<U>(&self)
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where
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T: Operation<U>,
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<T as Operation<U>>::Output: Bar,
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{
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<<T as Operation<U>>::Output as Bar>::error_occurs_here();
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}
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}
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trait Bar {
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fn error_occurs_here();
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}
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struct BarImpl<const N: usize>;
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impl<const N: usize> Bar for BarImpl<N> {
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fn error_occurs_here() {}
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}
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trait Operation<Rhs> {
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type Output;
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}
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//// Part-A: This causes error.
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impl<const M: usize, const N: usize> Operation<BarImpl<M>> for BarImpl<N>
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where
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BarImpl<{ N + M }>: Sized,
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{
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type Output = BarImpl<{ N + M }>;
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}
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//// Part-B: This doesn't cause error.
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// impl<const M: usize, const N: usize> Operation<BarImpl<M>> for BarImpl<N> {
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// type Output = BarImpl<M>;
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// }
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//// Part-C: This also doesn't cause error.
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// impl<const M: usize, const N: usize> Operation<BarImpl<M>> for BarImpl<N> {
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// type Output = BarImpl<{ M }>;
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// }
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