Landing: b90df55625eb

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Project / Subsystem

gcc / libstdc++

Date

2026-07-31

Author

Tomasz Kamiński

Commit

b90df55625eb40b05e0628097765d0a2cb368ced

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: libstdc++
patch_id: —
commit_hash: b90df55625eb40b05e0628097765d0a2cb368ced
source_type: github
headline: Reject user-defined specializations for coroutine_handle
tldr: User-defined specializations of `std::coroutine_handle` are now ill-formed, improving quality of implementation for coroutines.
author: Tomasz Kamiński
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • libstdc++
• coroutines
• standard compliance
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/b90df55625eb40b05e0628097765d0a2cb368ced
date: 2026-07-31T00:00:00.000Z

The C++ standard library now rejects user-defined specializations of std::coroutine_handle. This change aligns with the C++20 standard’s coroutines enhancements, which disallow such specializations, and provides a diagnostic when they are attempted.