Landing: 1a4d8dc0d2dc
Project / Subsystem
gcc / libstdc++
Date
2026-07-07
Author
Tomasz Kamiński
Commit
1a4d8dc0d2dc045bbb93654ae66fb80276dc6690
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- libstdc++
- patch_id
- —
- commit_hash
- 1a4d8dc0d2dc045bbb93654ae66fb80276dc6690
- source_type
- github
- headline
- Libstdc++ asserts layout_stride::mapping uniqueness.
- tldr
- Libstdc++ adds assertions to ensure unique layout_stride::mapping combinations.
- author
- Tomasz Kamiński
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • libstdc++
- • mdspan
- • assertions
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-07T00:00:00.000Z
Libstdc++ now asserts that the combination of strides and extents passed to layout_stride::mapping is unique. For performance in non-debug builds, only O(rank) checks are performed, while debug builds include an O(rank^2) check using an insertion-sort-based algorithm. This change also ensures consistent behavior for layout_stride mapping construction, aligning with LWG4603.