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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++/107886] Problem witch std::latch,
 std::binary_semaphores in C++20
Date: Mon, 28 Nov 2022 15:58:29 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107886

--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jamaika from comment #6)
> I don't understand something. Why _GLIBCXX_HAS_GTHREADS works for
> std::jthread but not for std::latch

std::jthread doesn't depend on _GLIBCXX_HAS_GTHREADS, it's always available.
But you might not be able to create a new thread using std::jthread if your
platform doesn't provide what's needed for it to work.

(In reply to Jamaika from comment #10)
> ```
> Using built-in specs.
> COLLECT_GCC=3Dg++.exe
> Target: x86_64-w64-mingw32
> Configured with: /home/ma/m/source/gcc-g/configure --host=3Dx86_64-w64-mi=
ngw32
> --target=3Dx86_64-w64-mingw32 --disable-nls
> --enable-languages=3Dc,c++,objc,obj-c++ --with-gmp=3D/home/ma/m/build/for=
_target
> --with-mpfr=3D/home/ma/m/build/for_target
> --with-mpc=3D/home/ma/m/build/for_target
> --with-isl=3D/home/ma/m/build/for_target --enable-twoprocess
> --disable-libstdcxx-pch --disable-win32-registry --disable-shared
> --enable-fully-dynamic-string --enable-libssp --prefix=3D/home/ma/m/target
> --with-sysroot=3D/home/ma/m/target
> Thread model: win32

This is the problem. You need a thread model that provides the support need=
ed
for C++.=