bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Rollup merge of #127275 - RalfJung:offset-from-isize-min, r=Amanieu

Browse source 
offset_from, offset: clearly separate safety requirements the user needs to prove from corollaries that automatically follow

By landing https://github.com/rust-lang/rust/pull/116675 we decided that objects larger than `isize::MAX` cannot exist in the address space of a Rust program, which lets us simplify these rules.

For `offset_from`, we can even state that the *absolute* distance fits into an `isize`, and therefore exclude `isize::MIN`. This PR also changes Miri to treat an `isize::MIN` difference like the other isize-overflowing cases.
This commit is contained in:
Matthias Krüger 2024-07-06 13:26:25 +02:00 • committed by GitHub
commit 2137d19ef6
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
6 changed files with 139 additions and 272 deletions
Download patch file Download diff file Expand all files Collapse all files

4
compiler/rustc_const_eval/src/interpret/intrinsics.rs
View file

@ -301,9 +301,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
}
// The signed form of the intrinsic allows this. If we interpret the
// difference as isize, we'll get the proper signed difference. If that
// seems *positive*, they were more than isize::MAX apart.
// seems *positive* or equal to isize::MIN, they were more than isize::MAX apart.
let dist = val.to_target_isize(self)?;
if dist >= 0 {
if dist >= 0 || i128::from(dist) == self.pointer_size().signed_int_min() {
throw_ub_custom!(
fluent::const_eval_offset_from_underflow,
name = intrinsic_name,