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Rollup merge of #121782 - RalfJung:mutable-ref-in-static, r=oli-obk

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allow statics pointing to mutable statics

Fixes https://github.com/rust-lang/rust/issues/120450 for good. We can even simplify our checks: no need to specifically go looking for mutable references in const, we can just reject any reference that points to something mutable.

r? `@oli-obk`
This commit is contained in:
Matthias Krüger 2024-02-29 20:50:04 +01:00 • committed by GitHub
commit 255fdcc858
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12 changed files with 64 additions and 307 deletions
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2
compiler/rustc_const_eval/src/errors.rs
View file

@ -613,7 +613,6 @@ impl<'tcx> ReportErrorExt for ValidationErrorInfo<'tcx> {
PartialPointer => const_eval_validation_partial_pointer,
ConstRefToMutable => const_eval_validation_const_ref_to_mutable,
ConstRefToExtern => const_eval_validation_const_ref_to_extern,
MutableRefInConstOrStatic => const_eval_validation_mutable_ref_in_const_or_static,
MutableRefToImmutable => const_eval_validation_mutable_ref_to_immutable,
NullFnPtr => const_eval_validation_null_fn_ptr,
NeverVal => const_eval_validation_never_val,
@ -767,7 +766,6 @@ impl<'tcx> ReportErrorExt for ValidationErrorInfo<'tcx> {
}
NullPtr { .. }
| PtrToStatic { .. }
| MutableRefInConstOrStatic
| ConstRefToMutable
| ConstRefToExtern
| MutableRefToImmutable

25
compiler/rustc_const_eval/src/interpret/validity.rs
View file

@ -148,14 +148,6 @@ impl CtfeValidationMode {
}
}
}
fn may_contain_mutable_ref(self) -> bool {
match self {
CtfeValidationMode::Static { mutbl } => mutbl == Mutability::Mut,
CtfeValidationMode::Promoted { .. } => false,
CtfeValidationMode::Const { .. } => false,
}
}
}
/// State for tracking recursive validation of references
@ -511,20 +503,19 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
// If this allocation has size zero, there is no actual mutability here.
let (size, _align, _alloc_kind) = self.ecx.get_alloc_info(alloc_id);
if size != Size::ZERO {
// Mutable pointer to immutable memory is no good.
if ptr_expected_mutbl == Mutability::Mut
&& alloc_actual_mutbl == Mutability::Not
{
throw_validation_failure!(self.path, MutableRefToImmutable);
}
if ptr_expected_mutbl == Mutability::Mut
&& self.ctfe_mode.is_some_and(|c| !c.may_contain_mutable_ref())
{
throw_validation_failure!(self.path, MutableRefInConstOrStatic);
}
if alloc_actual_mutbl == Mutability::Mut
&& matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. }))
{
throw_validation_failure!(self.path, ConstRefToMutable);
// In a const, everything must be completely immutable.
if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. })) {
if ptr_expected_mutbl == Mutability::Mut
|| alloc_actual_mutbl == Mutability::Mut
{
throw_validation_failure!(self.path, ConstRefToMutable);
}
}
}
// Potentially skip recursive check.