21 lines
624 B
Rust
21 lines
624 B
Rust
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trait Mirror {
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type Assoc;
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}
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impl<T> Mirror for T {
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type Assoc = T;
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}
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trait Foo {}
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// Even though using fulfillment in coherence allows us to figure out that
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// `?T = ()`, we still treat it as incoherent because `(): Iterator` may be
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// added upstream.
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impl<T> Foo for T where (): Mirror<Assoc = T> {}
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//~^ NOTE first implementation here
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impl<T> Foo for T where T: Iterator {}
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//~^ ERROR conflicting implementations of trait `Foo` for type `()`
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//~| NOTE conflicting implementation for `()`
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//~| NOTE upstream crates may add a new impl of trait `std::iter::Iterator` for type `()` in future versions
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fn main() {}
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