Landing: 72fc51b1ac64

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Project / Subsystem

gcc / libstdc++

Date

2026-04-30

Author

Jonathan Wakely

Commit

72fc51b1ac6451b2986d3351158b46b36827caf6

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: libstdc++
patch_id: —
commit_hash: 72fc51b1ac6451b2986d3351158b46b36827caf6
source_type: github
headline: libstdc++: Improve SFINAE-friendliness of `std::unique_ptr<void>::operator*`.
tldr: Makes `std::unique_ptr<void>::operator*` SFINAE-friendly by adding a constraint for C++20 and adjusting the noexcept-specifier for older standards.
author: Jonathan Wakely
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • libstdc++
• unique_ptr
• sfinae
• lwg
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/72fc51b1ac6451b2986d3351158b46b36827caf6
date: 2026-04-30T00:00:00.000Z

This commit implements LWG 4324, addressing the issue that std::unique_ptr<void>::operator* was not SFINAE-friendly due to the addition of a noexcept specifier in C++23 (LWG 2762). For C++20, a requires clause is added to constrain the function. For C++11/14/17, the noexcept specifier is adjusted to avoid ill-formed code. This change restores the original semantics, allowing code to check for the existence of the function in a SFINAE context without causing errors.