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19 lines
567 B
Rust
19 lines
567 B
Rust
// Test an `exists<'a> { forall<'b> { 'a = 'b } }` pattern -- which should not compile!
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//
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// In particular, we test this pattern in trait solving, where it is not connected
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// to any part of the source code.
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fn foo<'a>() -> fn(&'a u32) {
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panic!()
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}
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fn main() {
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// Here, proving that `fn(&'a u32) <: for<'b> fn(&'b u32)`:
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//
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// - instantiates `'b` with a placeholder `!b`,
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// - requires that `&!b u32 <: &'a u32` and hence that `!b: 'a`,
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// - but we can never know this.
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let _: for<'b> fn(&'b u32) = foo(); //~ ERROR mismatched types
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}
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