[Bug libstdc++/64638] Build failure with recent futex changes in libstdc++, likely all non-futex targets

[hp at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64638

Hans-Peter Nilsson <hp at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |redi at gcc dot gnu.org

--- Comment #2 from Hans-Peter Nilsson <hp at gcc dot gnu.org> ---
At the risk of waving a red herring, in revision r219770, I see:

+++ libstdc++-v3/include/bits/atomic_futex.h    (revision 219770)
...
+#if !defined(_GLIBCXX_HAVE_LINUX_FUTEX)
+#include <mutex>
+#include <condition_variable>
+#endif

(no guard _GLIBCXX_HAS_GTHREADS)

but in include/std/condition_variable and mutex, respectively
#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
...
#ifdef _GLIBCXX_HAS_GTHREADS
around the interesting bits (class mutex etc.)

and in the build log:
checking for gthreads library... no

so, is a #ifdef _GLIBCXX_HAS_GTHREADS just missing from atomic_futex.h (or some
similar missing guard)?

CC:ing reviewer.