Landing: 874605e8c44c

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Project / Subsystem

gcc / libstdc++

Date

2026-07-16

Author

Jakub Jelinek

Commit

874605e8c44ca4823cedb2881cdbd91f38cff5bc

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: libstdc++
patch_id: —
commit_hash: 874605e8c44ca4823cedb2881cdbd91f38cff5bc
source_type: github
headline: libstdc++: Prevent specialization of std::indirect and std::polymorphic
tldr: std::indirect and std::polymorphic are marked to disallow user specialization, following C++ standard proposals.
author: Jakub Jelinek
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • libstdc++
• templates
• C++ standard
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/874605e8c44ca4823cedb2881cdbd91f38cff5bc
date: 2026-07-16T00:00:00.000Z

This commit prevents users from specializing the std::indirect and std::polymorphic templates in libstdc++. These templates, introduced based on C++ standard proposals P3019R14, already have inherent restrictions that preclude user specialization. By marking them with _GLIBCXX_NO_SPECIALIZATIONS, the compiler enforces these restrictions, enhancing type safety and preventing potential misuse.