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From: "pdimov at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/108836] New: std::mutex disappears in single-threaded
 libstdc++ builds
Date: Fri, 17 Feb 2023 15:27:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108836

            Bug ID: 108836
           Summary: std::mutex disappears in single-threaded libstdc++
                    builds
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pdimov at gmail dot com
  Target Milestone: ---

We've been getting reports in Boost that our uses of <mutex> and std::mutex
don't work in a single-threaded build of libstdc++, so we had to add
configuration macros to avoid these issues. One example is
https://github.com/boostorg/system/commit/53c00841fc0d892bf43cda60e3ea2f05c=
4362b32,
another https://github.com/boostorg/url/issues/684.

Is there a reason not to make std::mutex available in single threaded build=
s,
with its operations being no-ops?=