>From aa8aa5d8866366c06d3f06d9ac1cf8cd3614cf88 Mon Sep 17 00:00:00 2001
From: Bruno Haible <address@hidden>
Subject: [PATCH 1/5] 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.
---
 ChangeLog             | 13 +++++++++++++
 lib/pthread-mutex.c   | 19 +++++++++++++++++++
 m4/pthread-mutex.m4   | 29 ++++++++++++++++++++++++++++-
 modules/pthread-mutex |  3 ++-
 4 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 1217f31..4d99aca 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2019-11-21  Bruno Haible  <address@hidden>
+
+	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.
+
 2019-11-19  Bruno Haible  <address@hidden>
 
 	threads-h tests: Fix typo.
diff --git a/lib/pthread-mutex.c b/lib/pthread-mutex.c
index 7a6fc1a..96a225d 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
diff --git a/m4/pthread-mutex.m4 b/m4/pthread-mutex.m4
index c7d74f9..abe5f2f 100644
--- a/m4/pthread-mutex.m4
+++ b/m4/pthread-mutex.m4
@@ -1,4 +1,4 @@
-# pthread-mutex.m4 serial 1
+# pthread-mutex.m4 serial 2
 dnl Copyright (C) 2019 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -39,6 +39,33 @@ AC_DEFUN([gl_PTHREAD_MUTEX],
       dnl HAVE_PTHREAD_MUTEX_TIMEDLOCK is set in pthread_mutex_timedlock.m4.
       HAVE_PTHREAD_MUTEX_UNLOCK=0
       HAVE_PTHREAD_MUTEX_DESTROY=0
+    else
+      AC_CACHE_CHECK([for pthread_mutexattr_getrobust],
+        [gl_cv_func_pthread_mutexattr_getrobust],
+        [saved_LIBS="$LIBS"
+         LIBS="$LIBS $LIBMULTITHREAD"
+         AC_LINK_IFELSE(
+           [AC_LANG_SOURCE(
+              [[extern
+                #ifdef __cplusplus
+                "C"
+                #endif
+                int pthread_mutexattr_getrobust (void);
+                int main ()
+                {
+                  return pthread_mutexattr_getrobust ();
+                }
+              ]])],
+           [gl_cv_func_pthread_mutexattr_getrobust=yes],
+           [gl_cv_func_pthread_mutexattr_getrobust=no])
+         LIBS="$saved_LIBS"
+        ])
+      if test $gl_cv_func_pthread_mutexattr_getrobust = no; then
+        HAVE_PTHREAD_MUTEXATTR_GETROBUST=0
+        HAVE_PTHREAD_MUTEXATTR_SETROBUST=0
+        AC_DEFINE([PTHREAD_MUTEXATTR_ROBUST_UNIMPLEMENTED], [1],
+          [Define if the 'robust' attribute of pthread_mutex* doesn't exist.])
+      fi
     fi
   fi
 ])
diff --git a/modules/pthread-mutex b/modules/pthread-mutex
index 8e64a9e..71496b7 100644
--- a/modules/pthread-mutex
+++ b/modules/pthread-mutex
@@ -13,7 +13,8 @@ windows-timedrecmutex   [test $gl_threads_api = windows]
 
 configure.ac:
 gl_PTHREAD_MUTEX
-if test $HAVE_PTHREAD_MUTEX_INIT = 0 || test $REPLACE_PTHREAD_MUTEX_INIT = 1; then
+if test $HAVE_PTHREAD_MUTEX_INIT = 0 || test $REPLACE_PTHREAD_MUTEX_INIT = 1 \
+   || test $HAVE_PTHREAD_MUTEXATTR_GETROBUST = 0 || test $REPLACE_PTHREAD_MUTEXATTR_GETROBUST = 1; then
   AC_LIBOBJ([pthread-mutex])
 fi
 gl_PTHREAD_MODULE_INDICATOR([pthread-mutex])
-- 
2.7.4