Unnamed repository; edit this file 'description' to name the repository.
fix
Added the regression test unsized_from_keeps_type_info that builds
minimal MyBox/MyRc stand-ins with CoerceUnsized + From to mirror the
original Rc::from(Box<[i32]>) scenario and assert that the inferred type
for rc stays MyRc<[i32]>.
The fixture uses only minicore pieces (coerce_unsized, from) so it
exercises the unsized coercion path entirely within the test harness,
ensuring we’ll catch future regressions without needing real Box/Rc.
| -rw-r--r-- | crates/hir-ty/src/tests/coercion.rs | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/crates/hir-ty/src/tests/coercion.rs b/crates/hir-ty/src/tests/coercion.rs index 50aca16365..36630ab587 100644 --- a/crates/hir-ty/src/tests/coercion.rs +++ b/crates/hir-ty/src/tests/coercion.rs @@ -88,6 +88,47 @@ fn test(a: A<[u8; 2]>, b: B<[u8; 2]>, c: C<[u8; 2]>) { } #[test] +fn unsized_from_keeps_type_info() { + check_types( + r#" +//- minicore: coerce_unsized, from +use core::{marker::Unsize, ops::CoerceUnsized}; + +struct MyBox<T: ?Sized> { + ptr: *const T, +} + +impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<MyBox<U>> for MyBox<T> {} + +struct MyRc<T: ?Sized> { + ptr: *const T, +} + +impl<T: ?Sized> core::convert::From<MyBox<T>> for MyRc<T> { + fn from(_: MyBox<T>) -> MyRc<T> { + loop {} + } +} + +fn make_box() -> MyBox<[i32; 2]> { + loop {} +} + +fn take<T: ?Sized>(value: MyRc<T>) -> MyRc<T> { + value +} + +fn test() { + let boxed: MyBox<[i32]> = make_box(); + let rc = MyRc::from(boxed); + //^^ MyRc<[i32]> + let _: MyRc<[i32]> = take(rc); +} +"#, + ); +} + +#[test] fn if_coerce() { check_no_mismatches( r#" |