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Add a debug check for ordering, and check for isize overflow in CTFE

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This commit is contained in:
Scott McMurray 2022-04-09 16:29:39 -07:00
parent e76b3f3b5b
commit 4bb15b3797
2 changed files with 14 additions and 3 deletions
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13
compiler/rustc_const_eval/src/interpret/intrinsics.rs
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@ -365,10 +365,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
} else {
usize_layout
};
let a_offset = ImmTy::from_uint(a_offset.bytes(), usize_layout);
let b_offset = ImmTy::from_uint(b_offset.bytes(), usize_layout);
let (val, _overflowed, _ty) =
// The subtraction is always done in `isize` to enforce
// the "no more than `isize::MAX` apart" requirement.
let a_offset = ImmTy::from_uint(a_offset.bytes(), isize_layout);
let b_offset = ImmTy::from_uint(b_offset.bytes(), isize_layout);
let (val, overflowed, _ty) =
self.overflowing_binary_op(BinOp::Sub, &a_offset, &b_offset)?;
if overflowed {
throw_ub_format!("Pointers were too far apart for {}", intrinsic_name);
}
let pointee_layout = self.layout_of(substs.type_at(0))?;
let val = ImmTy::from_scalar(val, ret_layout);
let size = ImmTy::from_int(pointee_layout.size.bytes(), ret_layout);

4
library/core/src/ptr/const_ptr.rs
View File

@ -678,6 +678,10 @@ impl<T: ?Sized> *const T {
where
T: Sized,
{
// SAFETY: The comparison has no side-effects, and the intrinsic
// does this check internally in the CTFE implementation.
unsafe { assert_unsafe_precondition!(self >= origin) };
let pointee_size = mem::size_of::<T>();
assert!(0 < pointee_size && pointee_size <= isize::MAX as usize);
// SAFETY: the caller must uphold the safety contract for `ptr_offset_from_unsigned`.