34 lines
1.3 KiB
Rust
34 lines
1.3 KiB
Rust
// run-pass
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// This is a regression test for the ICE from issue #10846.
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//
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// The original issue causing the ICE: the LUB-computations during
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// type inference were encountering late-bound lifetimes, and
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// asserting that such lifetimes should have already been substituted
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// with a concrete lifetime.
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//
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// However, those encounters were occurring within the lexical scope
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// of the binding for the late-bound lifetime; that is, the late-bound
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// lifetimes were perfectly valid. The core problem was that the type
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// folding code was over-zealously passing back all lifetimes when
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// doing region-folding, when really all clients of the region-folding
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// case only want to see FREE lifetime variables, not bound ones.
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// pretty-expanded FIXME #23616
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pub fn main() {
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fn explicit() {
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fn test<F>(_x: Option<Box<F>>) where F: FnMut(Box<dyn for<'a> FnMut(&'a isize)>) {}
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test(Some(Box::new(|_f: Box<dyn for<'a> FnMut(&'a isize)>| {})));
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}
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// The code below is shorthand for the code above (and more likely
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// to represent what one encounters in practice).
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fn implicit() {
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fn test<F>(_x: Option<Box<F>>) where F: FnMut(Box<dyn FnMut(& isize)>) {}
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test(Some(Box::new(|_f: Box<dyn FnMut(& isize)>| {})));
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}
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explicit();
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implicit();
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}
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