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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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37
compiler/rustc_hir_typeck/src/cast.rs
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@ -1042,30 +1042,31 @@ impl<'a, 'tcx> CastCheck<'tcx> {
m_cast: ty::TypeAndMut<'tcx>,
) -> Result<CastKind, CastError<'tcx>> {
// array-ptr-cast: allow mut-to-mut, mut-to-const, const-to-const
if m_expr.mutbl >= m_cast.mutbl {
if let ty::Array(ety, _) = m_expr.ty.kind() {
// Due to the limitations of LLVM global constants,
// region pointers end up pointing at copies of
// vector elements instead of the original values.
// To allow raw pointers to work correctly, we
// need to special-case obtaining a raw pointer
// from a region pointer to a vector.
if m_expr.mutbl >= m_cast.mutbl
&& 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,
// region pointers end up pointing at copies of
// vector elements instead of the original values.
// To allow raw pointers to work correctly, we
// need to special-case obtaining a raw pointer
// from a region pointer to a vector.
// Coerce to a raw pointer so that we generate RawPtr in MIR.
let array_ptr_type = Ty::new_ptr(fcx.tcx, m_expr.ty, m_expr.mutbl);
fcx.coerce(self.expr, self.expr_ty, array_ptr_type, AllowTwoPhase::No, None)
.unwrap_or_else(|_| {
bug!(
// Coerce to a raw pointer so that we generate RawPtr in MIR.
let array_ptr_type = Ty::new_ptr(fcx.tcx, m_expr.ty, m_expr.mutbl);
fcx.coerce(self.expr, self.expr_ty, array_ptr_type, AllowTwoPhase::No, None)
.unwrap_or_else(|_| {
bug!(
"could not cast from reference to array to pointer to array ({:?} to {:?})",
self.expr_ty,
array_ptr_type,
)
});
});
// this will report a type mismatch if needed
fcx.demand_eqtype(self.span, *ety, m_cast.ty);
return Ok(CastKind::ArrayPtrCast);
}
// this will report a type mismatch if needed
fcx.demand_eqtype(self.span, *ety, m_cast.ty);
return Ok(CastKind::ArrayPtrCast);
}
Err(CastError::IllegalCast)