If you're using std::thread then you always needed to link to libpthread or
you'd get an exception at run time.
Now you get a failure earlier at link time, but there's no new dependency.
On Jun 6, 2015 6:24 PM, "Sam Varshavchik" <mrsam@xxxxxxxxxxxxxxx> wrote:
> Rebuilding a bunch of code from 4.9.2 to 5.1.1 resulted in a bunch of
> complaints about unresolved references to pthread_create(), and admonishing
> me for not linking with -lpthread :-)
>
> Which was odd, since the code in question uses std::thread exclusively,
> and should only need to be linked with the default libstdc++, helpfully
> supplied by the compiler.
>
No. Libstdc++ never linked to libpthread, it was always your job.
> So, I chased this down to <thread> now making visible an explicit
> reference to pthread_create, in std::thread's constructor:
>
> template<typename _Callable, typename… _Args>
> explicit
> thread(_Callable&& __f, _Args&&… __args)
> {
> _M_start_thread(_M_make_routine(std::__bind_simple(
> std::forward<_Callable>(__f),
> std::forward<_Args>(__args)…)),
> reinterpret_cast<void(*)()>(&pthread_create));
> }
>
> So that's what I'm compiling. This may be because of the ld.so
> configuration in Fedora. Even if libstdc++ is linked with -lpthread, this
> ends up b compiled as part of my code, at -O2, apparently, and I'm not
> linking with -lpthread.
>
> Not really a complicated thing to fix up, of course. Just seems a bit odd,
> to end up requiring a linking dependency, in this manner.
>
>
