pthread-mutex: Fix errors in C++ mode.

* m4/pthread-mutex.m4 (gl_PTHREAD_MUTEX): Test whether
pthread_mutexattr_getrobust exists. If not, define
PTHREAD_MUTEXATTR_ROBUST_UNIMPLEMENTED.
* lib/pthread-mutex.c (pthread_mutexattr_getrobust,
pthread_mutexattr_setrobust): Define also if <pthread.h> exists but
PTHREAD_MUTEXATTR_ROBUST_UNIMPLEMENTED.
* modules/pthread-mutex (configure.ac): Compile pthread-mutex.c also
when <pthread.h> exists but pthread_mutexattr_getrobust needs a gnulib
definition.

1 files changed, 19 insertions, 0 deletions

diff --git a/lib/pthread-mutex.c b/lib/pthread-mutex.c
index 7a6fc1a722..96a225daee 100644
--- a/lib/pthread-mutex.c
+++ b/lib/pthread-mutex.c
@@ -82,6 +82,25 @@ pthread_mutexattr_destroy (pthread_mutexattr_t *attr _GL_UNUSED)
   return 0;
 }
 
+#elif PTHREAD_MUTEXATTR_ROBUST_UNIMPLEMENTED
+
+int
+pthread_mutexattr_getrobust (const pthread_mutexattr_t *attr, int *robustp)
+{
+  *robustp = PTHREAD_MUTEX_STALLED;
+  return 0;
+}
+
+int
+pthread_mutexattr_setrobust (pthread_mutexattr_t *attr, int robust)
+{
+  if (!(robust == PTHREAD_MUTEX_STALLED || robust == PTHREAD_MUTEX_ROBUST))
+    return EINVAL;
+  if (!(robust == PTHREAD_MUTEX_STALLED))
+    return ENOTSUP;
+  return 0;
+}
+
 #endif
 
 #if (defined _WIN32 && ! defined __CYGWIN__) && USE_WINDOWS_THREADS