mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-22 23:04:33 +00:00
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
|
|
// one is more general than the other. Test the case where the more general type
|
|
// (`x`) is the second match arm specifically.
|
|
//
|
|
// FIXME(#73154) Pure NLL checker without leak check accepts this test.
|
|
// (Note that it still errors in old-lub-glb-hr-noteq1.rs). What happens
|
|
// is that, due to the ordering of the match arms, we pick the correct "more
|
|
// general" fn type, and we ignore the errors from the non-NLL type checker that
|
|
// requires equality. The NLL type checker only requires a subtyping
|
|
// relationship, and that holds. To unblock landing NLL - and ensure that we can
|
|
// choose to make this always in error in the future - we perform the leak check
|
|
// after coercing a function pointer.
|
|
|
|
// revisions: leak noleak
|
|
//[noleak] compile-flags: -Zno-leak-check
|
|
|
|
//[noleak] check-pass
|
|
|
|
fn foo(x: for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8, y: for<'a> fn(&'a u8, &'a u8) -> &'a u8) {
|
|
// The two types above are not equivalent. With the older LUB/GLB
|
|
// algorithm, this may have worked (I don't remember), but now it
|
|
// doesn't because we require equality.
|
|
let z = match 22 {
|
|
0 => y,
|
|
_ => x,
|
|
//[leak]~^ ERROR `match` arms have incompatible types
|
|
};
|
|
}
|
|
|
|
fn foo_cast(x: for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8, y: for<'a> fn(&'a u8, &'a u8) -> &'a u8) {
|
|
// But we can *upcast* explicitly the type of `x` and figure
|
|
// things out:
|
|
let z = match 22 {
|
|
0 => x as for<'a> fn(&'a u8, &'a u8) -> &'a u8,
|
|
_ => y,
|
|
};
|
|
}
|
|
|
|
fn main() {}
|