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Rollup merge of #138962 - xizheyin:issue-138836, r=compiler-errors

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Expect an array when expected and acutal types are both arrays during cast

Closes #138836
This commit is contained in:
Jacob Pratt 2025-04-13 17:37:52 -04:00 • committed by GitHub
commit 60c76b9dfd
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5 changed files with 37 additions and 22 deletions
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7
compiler/rustc_hir_typeck/src/cast.rs
View file

@ -1042,8 +1042,10 @@ impl<'a, 'tcx> CastCheck<'tcx> {
m_cast: ty::TypeAndMut<'tcx>, m_cast: ty::TypeAndMut<'tcx>,
) -> Result<CastKind, CastError<'tcx>> { ) -> Result<CastKind, CastError<'tcx>> {
// array-ptr-cast: allow mut-to-mut, mut-to-const, const-to-const // array-ptr-cast: allow mut-to-mut, mut-to-const, const-to-const
if m_expr.mutbl >= m_cast.mutbl { if m_expr.mutbl >= m_cast.mutbl
if let ty::Array(ety, _) = m_expr.ty.kind() { && let ty::Array(ety, _) = m_expr.ty.kind()
&& fcx.can_eq(fcx.param_env, *ety, m_cast.ty)
{
// Due to the limitations of LLVM global constants, // Due to the limitations of LLVM global constants,
// region pointers end up pointing at copies of // region pointers end up pointing at copies of
// vector elements instead of the original values. // vector elements instead of the original values.
@ -1066,7 +1068,6 @@ impl<'a, 'tcx> CastCheck<'tcx> {
fcx.demand_eqtype(self.span, *ety, m_cast.ty); fcx.demand_eqtype(self.span, *ety, m_cast.ty);
return Ok(CastKind::ArrayPtrCast); return Ok(CastKind::ArrayPtrCast);
} }
}
Err(CastError::IllegalCast) Err(CastError::IllegalCast)
} }

5
tests/ui/cast/cast-array-issue-138836.rs Normal file
View file

@ -0,0 +1,5 @@
fn main() {
let a: [u8; 3] = [1,2,3];
let b = &a;
let c = b as *const [u32; 3]; //~ ERROR casting `&[u8; 3]` as `*const [u32; 3]` is invalid
}

9
tests/ui/cast/cast-array-issue-138836.stderr Normal file
View file

@ -0,0 +1,9 @@
error[E0606]: casting `&[u8; 3]` as `*const [u32; 3]` is invalid
--> $DIR/cast-array-issue-138836.rs:4:13
|
LL | let c = b as *const [u32; 3];
| ^^^^^^^^^^^^^^^^^^^^
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0606`.

2
tests/ui/consts/const-cast-wrong-type.rs
View file

@ -1,5 +1,5 @@
const a: [u8; 3] = ['h' as u8, 'i' as u8, 0 as u8]; const a: [u8; 3] = ['h' as u8, 'i' as u8, 0 as u8];
const b: *const i8 = &a as *const i8; //~ ERROR mismatched types const b: *const i8 = &a as *const i8; //~ ERROR casting `&[u8; 3]` as `*const i8` is invalid
fn main() { fn main() {
} }

6
tests/ui/consts/const-cast-wrong-type.stderr
View file

@ -1,9 +1,9 @@
error[E0308]: mismatched types error[E0606]: casting `&[u8; 3]` as `*const i8` is invalid
--> $DIR/const-cast-wrong-type.rs:2:22 --> $DIR/const-cast-wrong-type.rs:2:22
| |
LL | const b: *const i8 = &a as *const i8; LL | const b: *const i8 = &a as *const i8;
| ^^^^^^^^^^^^^^^ expected `u8`, found `i8` | ^^^^^^^^^^^^^^^
error: aborting due to 1 previous error error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0308`. For more information about this error, try `rustc --explain E0606`.