Specify thread model on ubuntu mingw (if possible) - c++

Question

Im running a program on linux with g++ and everything works fine. If i compile using x86_64-w64-mingw32-g++ it crashes with error: ‘std::thread’ has not been declared.
The part where my code crashed is fairly simple:
#include <thread>
int main()
{
int cores = std::thread::hardware_concurrency();
}
I figured out that mingw uses win32 threads, i want it to use posix threads. Version is:
:~$ x86_64-w64-mingw32-g++ -v
Using built-in specs.
COLLECT_GCC=x86_64-w64-mingw32-g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-w64-mingw32/9.3-win32/lto-wrapper
Target: x86_64-w64-mingw32
Configured with: ../../src/configure --build=x86_64-linux-gnu --prefix=/usr --includedir='/usr/include' --mandir='/usr/share/man' --infodir='/usr/share/info' --sysconfdir=/etc --localstatedir=/var --disable-silent-rules --libdir='/usr/lib/x86_64-linux-gnu' --libexecdir='/usr/lib/x86_64-linux-gnu' --disable-maintainer-mode --disable-dependency-tracking --prefix=/usr --enable-shared --enable-static --disable-multilib --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --libdir=/usr/lib --enable-libstdcxx-time=yes --with-tune=generic --with-headers=/usr/x86_64-w64-mingw32/include --enable-version-specific-runtime-libs --enable-fully-dynamic-string --enable-libgomp --enable-languages=c,c++,fortran,objc,obj-c++,ada --enable-lto --enable-threads=win32 --program-suffix=-win32 --program-prefix=x86_64-w64-mingw32- --target=x86_64-w64-mingw32 --with-as=/usr/bin/x86_64-w64-mingw32-as --with-ld=/usr/bin/x86_64-w64-mingw32-ld --enable-libatomic --enable-libstdcxx-filesystem-ts=yes --enable-dependency-tracking
Thread model: win32
gcc version 9.3-win32 20200320 (GCC)
As you can see thread model is win32, (how) can i change it? In the mingw include paths there is a 9.3-posix folder, but it seems it isnt used so far.
As you can see here you can:
I'm installing mingw-w64 on Windows and there are two options: win32 threads and posix threads.
Is that possible on linux aswell?

Answer 1

It seems that the package g++-mingw-w64-x86-64 provides two executables:
x86_64-w64-mingw32-g++-posix: which uses posix
x86_64-w64-mingw32-g++-win32: which uses win32
Using the first executable should solve your issue.