Landing: 219d9f4b006e
Project / Subsystem
gcc / c++
Date
2026-04-17
Author
Jason Merrill
Commit
219d9f4b006e19ea49b0e1ca6706fc1204211eff
Source
github
Impact
6/10
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- c++
- patch_id
- —
- commit_hash
- 219d9f4b006e19ea49b0e1ca6706fc1204211eff
- source_type
- github
- headline
- C++: Improve constexpr call hashing and garbage collection.
- tldr
- Optimizes constexpr call hashing and garbage collection to prevent use-after-free issues in recursive lambda evaluations.
- why_it_matters
- Fixes a potential memory corruption issue in constexpr evaluation, leading to more stable and reliable compilation.
- author
- Jason Merrill
- impact_score
- 6
- impact_rationale
- Fixes a memory corruption issue, potentially preventing crashes or unexpected behavior during compilation.
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • C++
- • constexpr
- • garbage collection
- • memory management
- • lambdas
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-04-17T00:00:00.000Z
This commit addresses a use-after-free issue that could occur during the evaluation of recursive constexpr lambdas, particularly when the -Wtautological-compare flag is enabled. The fix involves unsharing bindings earlier in the cxx_eval_call_expression function, specifically when creating the entry in the constexpr_call_table. This ensures that the entry refers to valid memory, even after garbage collection.