Allow field(0) projection as a no-op when target value is a PtrLocal#871
Merged
Allow field(0) projection as a no-op when target value is a PtrLocal#871
Conversation
Stevengre
added a commit
that referenced
this pull request
Dec 1, 2025
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The change in #811 allows pointer casts between pointers to data and pointers to "transparent wrapper structs" containing one field with the same data. While the code tries to insert
field(0, _)projections when casting, this remediation falls short when the cast pointer is of a second degree, i.e., a pointer to a pointer.An example of this can be observed in
Iterator<_>::next, where a pointer**Tis cast to a pointer*NonNull<T>,NonNullbeing one of these "transparent wrapper structs".The proposed code change allows for a
field(0, _)projection to be treated as a No-Op when applied to a non-aggregate (nor union), specifically aPtrLocalfor the case ofnext().This fixes
iter.next()for cases whereSome(element)is returned. The case where it returnsNoneis a separate issue tested but not fixed here.