30 lines
881 B
Rust
30 lines
881 B
Rust
// Checks that Polonius can compute cases of universal regions errors:
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// "illegal subset relation errors", cases where analysis finds that
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// two free regions outlive each other, without any evidence that this
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// relation holds.
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//@ compile-flags: -Z polonius
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// returning `y` requires that `'b: 'a`, but it's not known to be true
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fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
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y //~ ERROR
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}
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// `'b: 'a` is explicitly declared
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fn valid_subset<'a, 'b: 'a>(x: &'a u32, y: &'b u32) -> &'a u32 {
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y
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}
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// because of `x`, it is implied that `'b: 'a` holds
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fn implied_bounds_subset<'a, 'b>(x: &'a &'b mut u32) -> &'a u32 {
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x
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}
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// `'b: 'a` is declared, and `'a: 'c` is known via implied bounds:
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// `'b: 'c` is therefore known to hold transitively
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fn transitively_valid_subset<'a, 'b: 'a, 'c>(x: &'c &'a u32, y: &'b u32) -> &'c u32 {
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y
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}
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fn main() {}
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