Landing: ce236336c841
Project / Subsystem
gcc / libstdc++
Date
2026-07-20
Author
Tomasz Kamiński
Commit
ce236336c8416fcdb47975dfebbeb5d9a40c609d
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- libstdc++
- patch_id
- —
- commit_hash
- ce236336c8416fcdb47975dfebbeb5d9a40c609d
- source_type
- github
- headline
- libstdc++: Implement zic writezone merge optimization
- tldr
- Optimize timezone data by merging adjacent zones with similar transitions.
- author
- Tomasz Kamiński
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • libstdc++
- • timezone
- • optimization
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-20T00:00:00.000Z
This change optimizes timezone data by implementing a merge optimization for zic. When two adjacent zones have different offsets but the new zone’s rule set includes a transition within a specific backward jump window, zic now folds that rule into the boundary itself. This ensures a single transition is emitted, starting with the post-rule save value rather than a brief pre-rule save period, improving accuracy for historical timezone boundaries.