40 lines
1.2 KiB
Rust
40 lines
1.2 KiB
Rust
//@ revisions: old next
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//@[next] compile-flags: -Znext-solver
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// cc #119820, the behavior here is inconsistent,
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// using the leak check to guide inference for `for<'a> Box<_>: Leak<'a>`
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// but not for `for<'a> Box<_>: IndirectLeak<'a>`.
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trait Leak<'a> {}
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impl Leak<'_> for Box<u32> {}
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impl Leak<'static> for Box<u16> {}
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fn impls_leak<T: for<'a> Leak<'a>>() {}
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fn direct() {
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// ok
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//
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// The `Box<u16>` impls fails the leak check,
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// meaning that we apply the `Box<u32>` impl.
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impls_leak::<Box<_>>();
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//[next]~^ ERROR type annotations needed
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}
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trait IndirectLeak<'a> {}
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impl<'a, T: Leak<'a>> IndirectLeak<'a> for T {}
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fn impls_indirect_leak<T: for<'a> IndirectLeak<'a>>() {}
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fn indirect() {
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// error: type annotations needed
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//
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// While the `Box<u16>` impl would fail the leak check
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// we have already instantiated the binder while applying
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// the generic `IndirectLeak` impl, so during candidate
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// selection of `Leak` we do not detect the placeholder error.
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// Evaluation of `Box<_>: Leak<'!a>` is therefore ambiguous,
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// resulting in `for<'a> Box<_>: Leak<'a>` also being ambiguous.
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impls_indirect_leak::<Box<_>>();
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//~^ ERROR type annotations needed
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}
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fn main() {}
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