Landing: 6112538b060d

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Project / Subsystem

gcc / c++/modules

Date

2026-05-05

Author

Patrick Palka

Commit

6112538b060d8a973500a3ae5e930545b422600f

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: c++/modules
patch_id: —
commit_hash: 6112538b060d8a973500a3ae5e930545b422600f
source_type: github
headline: c++/modules: Fixes false ABI tag mismatch with modules.
tldr: Resolves a false positive ABI tag mismatch in C++ modules by ignoring inherited tags during comparison when mangling status differs.
author: Patrick Palka
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • c++
• modules
• abi
• bugfix
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/6112538b060d8a973500a3ae5e930545b422600f
date: 2026-05-05T00:00:00.000Z

Fixes a false positive ABI tag mismatch error that could occur when using C++ modules. The issue arose when a variable inherited an ABI tag from another type, but the tag was only propagated during mangling. If one version of the variable was mangled and another was not, a mismatch would be detected during module merging. The fix makes the comparison routine ignore inherited tags when there’s a mangling status difference, preventing the false positive.