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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /src/test/ui/coercion/coerce-unsize-subtype.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/test/ui/coercion/coerce-unsize-subtype.rs')
-rw-r--r-- | src/test/ui/coercion/coerce-unsize-subtype.rs | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/src/test/ui/coercion/coerce-unsize-subtype.rs b/src/test/ui/coercion/coerce-unsize-subtype.rs new file mode 100644 index 000000000..45b53300c --- /dev/null +++ b/src/test/ui/coercion/coerce-unsize-subtype.rs @@ -0,0 +1,40 @@ +// run-pass +#![allow(dead_code)] +// pretty-expanded FIXME #23616 + +use std::rc::Rc; + +fn lub_short<'a, T>(_: &[&'a T], _: &[&'a T]) {} + +// The two arguments are a subtype of their LUB, after coercion. +fn long_and_short<'a, T>(xs: &[&'static T; 1], ys: &[&'a T; 1]) { + lub_short(xs, ys); +} + +// The argument coerces to a subtype of the return type. +fn long_to_short<'a, 'b, T>(xs: &'b [&'static T; 1]) -> &'b [&'a T] { + xs +} + +// Rc<T> is covariant over T just like &T. +fn long_to_short_rc<'a, T>(xs: Rc<[&'static T; 1]>) -> Rc<[&'a T]> { + xs +} + +// LUB-coercion (if-else/match/array) coerces `xs: &'b [&'static T: N]` +// to a subtype of the LUB of `xs` and `ys` (i.e., `&'b [&'a T]`), +// regardless of the order they appear (in if-else/match/array). +fn long_and_short_lub1<'a, 'b, T>(xs: &'b [&'static T; 1], ys: &'b [&'a T]) { + let _order1 = [xs, ys]; + let _order2 = [ys, xs]; +} + +// LUB-coercion should also have the exact same effect when `&'b [&'a T; N]` +// needs to be coerced, i.e., the resulting type is not &'b [&'static T], but +// rather the `&'b [&'a T]` LUB. +fn long_and_short_lub2<'a, 'b, T>(xs: &'b [&'static T], ys: &'b [&'a T; 1]) { + let _order1 = [xs, ys]; + let _order2 = [ys, xs]; +} + +fn main() {} |