38 lines
1.1 KiB
Rust
38 lines
1.1 KiB
Rust
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// Regression test for #55756.
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//
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// In this test, the result of `self.callee` is a projection `<D as
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// Database<'?0>>::Guard`. As it may contain a destructor, the dropck
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// rules require that this type outlivess the scope of `state`. Unfortunately,
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// our region inference is not smart enough to figure out how to
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// translate a requirement like
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//
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// <D as Database<'0>>::guard: 'r
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//
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// into a requirement that `'0: 'r` -- in particular, it fails to do
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// so because it *also* knows that `<D as Database<'a>>::Guard: 'a`
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// from the trait definition. Faced with so many choices, the current
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// solver opts to do nothing.
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//
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// Fixed by tweaking the solver to recognize that the constraint from
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// the environment duplicates one from the trait.
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//
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// compile-pass
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#![crate_type="lib"]
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pub trait Database<'a> {
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type Guard: 'a;
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}
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pub struct Stateful<'a, D: 'a>(&'a D);
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impl<'b, D: for <'a> Database<'a>> Stateful<'b, D> {
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pub fn callee<'a>(&'a self) -> <D as Database<'a>>::Guard {
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unimplemented!()
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}
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pub fn caller<'a>(&'a self) -> <D as Database<'a>>::Guard {
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let state = self.callee();
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unimplemented!()
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}
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}
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