mirror of https://github.com/rust-lang/rust
38 lines
1.1 KiB
Rust
38 lines
1.1 KiB
Rust
// Regression test for #74429, where we didn't think that a type parameter
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// outlived `ReEmpty`.
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//@ check-pass
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#![allow(dropping_copy_types)]
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use std::marker::PhantomData;
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fn apply<T, F: FnOnce(T)>(_: T, _: F) {}
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#[derive(Clone, Copy)]
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struct Invariant<T> {
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t: T,
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p: PhantomData<fn(T) -> T>,
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}
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fn verify_reempty<T>(x: T) {
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// r is inferred to have type `Invariant<&ReEmpty(U0) T>`
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let r = Invariant { t: &x, p: PhantomData };
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// Creates a new universe, all variables from now on are in `U1`, say.
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let _: fn(&()) = |_| {};
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// Closure parameter is of type `&ReEmpty(U1) T`, so the closure has an implied
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// bound of `T: ReEmpty(U1)`
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apply(&x, |_| {
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// Requires `typeof(r)` is well-formed, i.e. `T: ReEmpty(U0)`. If we
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// only have the implied bound from the closure parameter to use this
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// requires `ReEmpty(U1): ReEmpty(U0)`, which isn't true so we reported
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// an error.
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//
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// This doesn't happen any more because we ensure that `T: ReEmpty(U0)`
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// is an implicit bound for all type parameters.
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drop(r);
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});
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}
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fn main() {}
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