I just realized that it is possible to run a check by #undef - ing
__GTHREADS_CXX0X in async.h. Doing so promptly found another syntax
error, which this version of the patch fixes.
PR libfortran/123446
PR libfortran/119136
libgfortran/ChangeLog:
* io/async.h: DEBUG_ASYNC needs gtreads support.
(LOCK_UNIT): Only lock when there is pthreads support and it is active.
Otherwise, just set unit->self to 1.
(UNLOCK_UNIT): Only unlock when there is pthreads support and it is active.
Otherwise, just set unit->self to 0.
(TRYLOCK_UNIT): Only try locking when thee is pthreads support and it is
active. Otherwise, return unit->self.
(OWN_THREAD_ID): New macro.
* io/io.h: gfc_unit's self is an int when there is no gthreads support.
* io/unit.c (check_for_recursive): Check for equality of unit which
locked to OWN_THREAD_ID.
d5964a270d