diff options
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/validity.rs | 17 | ||||
| -rw-r--r-- | tests/ui/consts/unsafe_cell_in_const.rs | 15 |
2 files changed, 29 insertions, 3 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs index 7d76d925ef2..a42a92abd43 100644 --- a/compiler/rustc_const_eval/src/interpret/validity.rs +++ b/compiler/rustc_const_eval/src/interpret/validity.rs @@ -1086,8 +1086,13 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt, ) -> InterpResult<'tcx> { // Special check for CTFE validation, preventing `UnsafeCell` inside unions in immutable memory. if self.ctfe_mode.is_some_and(|c| !c.allow_immutable_unsafe_cell()) { - if !val.layout.is_zst() && !val.layout.ty.is_freeze(*self.ecx.tcx, self.ecx.typing_env) - { + // Unsized unions are currently not a thing, but let's keep this code consistent with + // the check in `visit_value`. + let zst = self + .ecx + .size_and_align_of(&val.meta(), &val.layout)? + .is_some_and(|(s, _a)| s.bytes() == 0); + if !zst && !val.layout.ty.is_freeze(*self.ecx.tcx, self.ecx.typing_env) { if !self.in_mutable_memory(val) { throw_validation_failure!(self.path, UnsafeCellInImmutable); } @@ -1131,7 +1136,13 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt, // Special check preventing `UnsafeCell` in the inner part of constants if self.ctfe_mode.is_some_and(|c| !c.allow_immutable_unsafe_cell()) { - if !val.layout.is_zst() + // Exclude ZST values. We need to compute the dynamic size/align to properly + // handle slices and trait objects. + let zst = self + .ecx + .size_and_align_of(&val.meta(), &val.layout)? + .is_some_and(|(s, _a)| s.bytes() == 0); + if !zst && let Some(def) = val.layout.ty.ty_adt_def() && def.is_unsafe_cell() { diff --git a/tests/ui/consts/unsafe_cell_in_const.rs b/tests/ui/consts/unsafe_cell_in_const.rs new file mode 100644 index 00000000000..b867ae1ba9f --- /dev/null +++ b/tests/ui/consts/unsafe_cell_in_const.rs @@ -0,0 +1,15 @@ +//! Ensure we do not complain about zero-sized `UnsafeCell` in a const in any form. +//! See <https://github.com/rust-lang/rust/issues/142948>. + +//@ check-pass +use std::cell::UnsafeCell; + +const X1: &mut UnsafeCell<[i32; 0]> = UnsafeCell::from_mut(&mut []); + +const X2: &mut UnsafeCell<[i32]> = UnsafeCell::from_mut(&mut []); + +trait Trait {} +impl Trait for [i32; 0] {} +const X3: &mut UnsafeCell<dyn Trait> = UnsafeCell::from_mut(&mut []); + +fn main() {} |