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From: "ilg at livius dot net" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/115422] New: Multi-threaded condition_variable app
 throws when linking as -static on Linux
Date: Mon, 10 Jun 2024 17:33:34 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 14.1.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: ilg at livius dot net
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115422

            Bug ID: 115422
           Summary: Multi-threaded condition_variable app throws when
                    linking as -static on Linux
           Product: gcc
           Version: 14.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ilg at livius dot net
  Target Milestone: ---

I have a test that checks C++ threads which synchronise via a
condition_variable.

The test runs fine on Linux/macOS/Windows, in various scenarios, except whe=
n I
build it as `-static` on Linux.

```
$ g++ sleepy-threads-cv.cpp -o sleepy-threads-cv -static -g -lpthread
$ ./static-sleepy-threads-cv 4
abcd
$ g++ sleepy-threads-cv.cpp -o static-sleepy-threads-cv -static -g -lpthread
$ ./static-sleepy-threads-cv 4
Segmentation fault
```

On some systems the result is an exception:

```
terminate called after throwing an instance of 'std::system_error'
  what():  Enable multithreading to use std::thread: Operation not permitted
```

I encountered the issue while building the xPack GCC 14 binaries, but later
confirmed it on GCC 13 and older.=20

The source code is attached.inside=20

The problem seems to be the global condition variable and/or mutex; if I mo=
ve
them inside the `spawnThreads()` function and pass pointers to them to all
threads, the test is functional even with `-static`.

Is there anything wrong with my test, or is this a small bug in libstdc++?=