mirror of https://github.com/rust-lang/rust
40 lines
1.5 KiB
Rust
40 lines
1.5 KiB
Rust
// Test taking the LUB of two function types that are not equatable but where
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// one is more general than the other. Test the case where the more general type
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// (`x`) is the second match arm specifically.
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//
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// FIXME(#73154) Pure NLL checker without leak check accepts this test.
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// (Note that it still errors in old-lub-glb-hr-noteq1.rs). What happens
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// is that, due to the ordering of the match arms, we pick the correct "more
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// general" fn type, and we ignore the errors from the non-NLL type checker that
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// requires equality. The NLL type checker only requires a subtyping
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// relationship, and that holds. To unblock landing NLL - and ensure that we can
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// choose to make this always in error in the future - we perform the leak check
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// after coercing a function pointer.
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//@ revisions: leak noleak
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//@[noleak] compile-flags: -Zno-leak-check
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//@[noleak] check-pass
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fn foo(x: for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8, y: for<'a> fn(&'a u8, &'a u8) -> &'a u8) {
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// The two types above are not equivalent. With the older LUB/GLB
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// algorithm, this may have worked (I don't remember), but now it
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// doesn't because we require equality.
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let z = match 22 {
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0 => y,
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_ => x,
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//[leak]~^ ERROR `match` arms have incompatible types
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};
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}
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fn foo_cast(x: for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8, y: for<'a> fn(&'a u8, &'a u8) -> &'a u8) {
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// But we can *upcast* explicitly the type of `x` and figure
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// things out:
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let z = match 22 {
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0 => x as for<'a> fn(&'a u8, &'a u8) -> &'a u8,
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_ => y,
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};
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}
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fn main() {}
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