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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/let-else/let-else-deref-coercion.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 '')
-rw-r--r-- | src/test/ui/let-else/let-else-deref-coercion.rs | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/src/test/ui/let-else/let-else-deref-coercion.rs b/src/test/ui/let-else/let-else-deref-coercion.rs new file mode 100644 index 000000000..87489d84b --- /dev/null +++ b/src/test/ui/let-else/let-else-deref-coercion.rs @@ -0,0 +1,75 @@ +// Taken from https://github.com/rust-lang/rust/blob/6cc0a764e082d9c0abcf37a768d5889247ba13e2/compiler/rustc_typeck/src/check/_match.rs#L445-L462 +// +// We attempt to `let Bar::Present(_) = foo else { ... }` where foo is meant to Deref/DerefMut to +// Bar. This fails, you must add a type annotation like `let _: &mut Bar = _ else { ... }` + +#![feature(let_else)] +use std::ops::{Deref, DerefMut}; + +struct Foo(Bar); + +enum Bar { + Present(u32), + Absent, +} +impl Deref for Foo { + type Target = Bar; + fn deref(&self) -> &Bar { + &self.0 + } +} +impl DerefMut for Foo { + fn deref_mut(&mut self) -> &mut Bar { + &mut self.0 + } +} +impl Bar { + fn bar(&self) -> Option<u32> { + let Bar::Present(z): &Bar = self else { + return None; + }; + return Some(*z); + } +} +impl Foo { + // Try without the type annotation + fn set_bar_unannotated(&mut self, value: u32) { + let Bar::Present(z) = self else { //~ ERROR mismatched types + return; + }; + *z = value; + } +} + +fn main() { + let mut foo = Foo(Bar::Present(1)); + foo.set_bar_unannotated(54); + assert_eq!(foo.bar(), Some(54)); + irrefutable::inner(); +} + +// The original, to show it fails for irrefutable let decls +mod irrefutable { + use std::ops::{Deref, DerefMut}; + struct Foo(Bar); + struct Bar(u32); + impl Deref for Foo { + type Target = Bar; + fn deref(&self) -> &Bar { + &self.0 + } + } + impl DerefMut for Foo { + fn deref_mut(&mut self) -> &mut Bar { + &mut self.0 + } + } + fn foo(x: &mut Foo) { + let Bar(z) = x; //~ ERROR mismatched types + *z = 54; + assert_eq!((x.0).0, 54); + } + pub fn inner() { + foo(&mut Foo(Bar(1))); + } +} |