Landing: 55a1efc2e04d

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Project / Subsystem

gcc / libstdc++

Date

2026-07-29

Author

Tomasz Kamiński

Commit

55a1efc2e04d7d7ecd5a19db3945b4231dbdc050

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: libstdc++
patch_id: —
commit_hash: 55a1efc2e04d7d7ecd5a19db3945b4231dbdc050
source_type: github
headline: Reject user-defined specializations for allocator_traits
tldr: User-defined specializations of `std::allocator_traits` are now rejected for C++23 and later, improving quality of implementation.
author: Tomasz Kamiński
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • libstdc++
• C++23
• standard compliance
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/55a1efc2e04d7d7ecd5a19db3945b4231dbdc050
date: 2026-07-29T00:00:00.000Z

In C++23 and later, user-defined specializations of std::allocator_traits are now explicitly disallowed. This change aligns with a C++ standard proposal (P2652R2) and improves the quality of implementation by making such specializations ill-formed, with diagnostics provided when attempted.