The feature gate for the issue is #![feature(const_ptr_offset_from)].

This tracks constness of the following function(s):

impl<T> *const T {
  const unsafe fn offset_from(self, origin: *const T) -> isize
}

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.

Steps

• Implementation
• Stabilization report: Tracking Issue for const offset_from (const_ptr_offset_from) #92980 (comment)
• Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

• Should we allow calling this function in case both pointers point to the same allocation (in terms of their provenance) but are not both in-bounds? Cc CTFE: there is no way to compute the difference between two ptrs in the same allocation if they might be out-of-bounds #92512
  → this can be resolved post-stabilization since it is backwards compatible

Implementation history

• see Tracking issue for ptr::offset_from (feature: ptr_offset_from) #41079
• CTFE/Miri: detect out-of-bounds pointers in offset_from #94827