>>>>> "Jakub" == Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
Jakub> What would be IMHO a good idea would be to use configure test for
Jakub> #include <thread>
Jakub> int t = std::thread::hardware_concurrency ();
Jakub> and in that case use that as a fallback to the previous implementation,
Jakub> that will be strictly an improvement.
FWIW, gdb had to do this. The check is in gdbsupport/common.m4.
I've appended it for convenience.
Tom
# Check for std::thread. This does not work on some platforms, like
# mingw and DJGPP.
AC_LANG_PUSH([C++])
AX_PTHREAD([threads=yes], [threads=no])
if test "$threads" = "yes"; then
save_LIBS="$LIBS"
LIBS="$PTHREAD_LIBS $LIBS"
save_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$PTHREAD_CFLAGS $save_CXXFLAGS"
AC_CACHE_CHECK([for std::thread],
gdb_cv_cxx_std_thread,
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
[[#include <thread>
void callback() { }]],
[[std::thread t(callback);]])],
gdb_cv_cxx_std_thread=yes,
gdb_cv_cxx_std_thread=no)])
# This check must be here, while LIBS includes any necessary
# threading library.
AC_CHECK_FUNCS([pthread_sigmask pthread_setname_np])
LIBS="$save_LIBS"
CXXFLAGS="$save_CXXFLAGS"
fi
if test "$gdb_cv_cxx_std_thread" = "yes"; then
AC_DEFINE(CXX_STD_THREAD, 1,
[Define to 1 if std::thread works.])
fi
AC_LANG_POP
