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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/108225] canadian compilation of gdb error for
 libstdc++'s std_mutex.h on x86_64-w64-mingw32 host
Date: Wed, 04 Jan 2023 13:32:32 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108225

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WONTFIX
             Status|WAITING                     |RESOLVED

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to cqwrteur from comment #3)
> libstdc++ completely ignores __GTHREAD_HAS_COND macro which cause build
> failure for gdb

If GDB requires <mutex> then it requires working C++11 thread support, which
has never worked for the win32 thread model with -D_WIN32_WINNT=3D0x0500.

With GCC 12, gthr-win32.h simply doesn't support std::mutex, period.

With GCC 13 it supports it for modern Windows versions:

/* Condition variables are supported on Vista and Server 2008 or later.  */
#if _WIN32_WINNT >=3D 0x0600
#define __GTHREAD_HAS_COND 1
#define __GTHREADS_CXX0X 1
#endif

For older Windows versions, the win32 thread model doesn't support std::mut=
ex
etc.

There is no C++11 threading support for Win95 using --enable-threads=3Dwin3=
2. If
you don't like it, either don't compile for Win95 or use a different thread
model.

Ranting and raving that unsupported things don't work is a waste of time.=