--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+2013-05-29  Paul Eggert  <eggert@cs.ucla.edu>
+
+	regex: adapt to locking regime instead of depending on pthread
+	Instead of depending on pthread, adapt to whatever thread
+	modules are in use.  Problem reported by Ludovic Courtès in
+	<http://lists.gnu.org/archive/html/bug-gnulib/2013-05/msg00082.html>
+	and by Mats Erik Andersson in
+	<http://lists.gnu.org/archive/html/bug-gnulib/2013-05/msg00100.html>.
+	* lib/regex_internal.h (lock_define, lock_init, lock_fini):
+	Support either the 'lock' module, or the 'pthread' module, or
+	no module.
+	(lock_lock, lock_unlock): New macros.
+	* lib/regexec.c (regexec, re_search_stub): Use the new macros.
+	* modules/lock, modules/pthread (configure.ac): Add module indicator.
+	* modules/regex (Depends-on): Remove pthread.
+
 2013-05-22  Eric Blake  <eblake@redhat.com>
 
 	getgroups: document portability issues

--- a/lib/regex_internal.h
+++ b/lib/regex_internal.h
@@ -33,24 +33,33 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#if defined _LIBC
+#ifdef _LIBC
 # include <bits/libc-lock.h>
-#endif
-/* Use __libc_lock_define (, NAME) if the library defines the macro,
-   and if the compiler is known to support empty macro arguments.  */
-#if (defined __libc_lock_define                                         \
-     && ((defined __GNUC__ && !defined __STRICT_ANSI__)                 \
-         || (defined __STDC_VERSION__ && 199901L <= __STDC_VERSION__)))
 # define lock_define(name) __libc_lock_define (, name)
 # define lock_init(lock) (__libc_lock_init (lock), 0)
 # define lock_fini(lock) 0
-#else
+# define lock_lock(lock) __libc_lock_lock (lock)
+# define lock_unlock(lock) __libc_lock_unlock (lock)
+#elif defined GNULIB_LOCK
+# include "glthread/lock.h"
+# define lock_define(name) gl_lock_define (, name)
+# define lock_init(lock) glthread_lock_init (&(lock))
+# define lock_fini(lock) glthread_lock_destroy (&(lock))
+# define lock_lock(lock) glthread_lock_lock (&(lock))
+# define lock_unlock(lock) glthread_lock_unlock (&(lock))
+#elif defined GNULIB_PTHREAD
 # include <pthread.h>
 # define lock_define(name) pthread_mutex_t name;
 # define lock_init(lock) pthread_mutex_init (&(lock), 0)
 # define lock_fini(lock) pthread_mutex_destroy (&(lock))
-# define __libc_lock_lock(lock) pthread_mutex_lock (&(lock))
-# define __libc_lock_unlock(lock) pthread_mutex_unlock (&(lock))
+# define lock_lock(lock) pthread_mutex_lock (&(lock))
+# define lock_unlock(lock) pthread_mutex_unlock (&(lock))
+#else
+# define lock_define(name)
+# define lock_init(lock) 0
+# define lock_fini(lock) 0
+# define lock_lock(lock) ((void) 0)
+# define lock_unlock(lock) ((void) 0)
 #endif
 
 /* In case that the system doesn't have isblank().  */

--- a/lib/regexec.c
+++ b/lib/regexec.c
@@ -244,14 +244,14 @@
       length = strlen (string);
     }
 
-  __libc_lock_lock (dfa->lock);
+  lock_lock (dfa->lock);
   if (preg->no_sub)
     err = re_search_internal (preg, string, length, start, length,
 			      length, 0, NULL, eflags);
   else
     err = re_search_internal (preg, string, length, start, length,
 			      length, nmatch, pmatch, eflags);
-  __libc_lock_unlock (dfa->lock);
+  lock_unlock (dfa->lock);
   return err != REG_NOERROR;
 }
 
@@ -430,7 +430,7 @@
   else if (BE (last_start < 0 || (range < 0 && start <= last_start), 0))
     last_start = 0;
 
-  __libc_lock_lock (dfa->lock);
+  lock_lock (dfa->lock);
 
   eflags |= (bufp->not_bol) ? REG_NOTBOL : 0;
   eflags |= (bufp->not_eol) ? REG_NOTEOL : 0;
@@ -494,7 +494,7 @@
     }
   re_free (pmatch);
  out:
-  __libc_lock_unlock (dfa->lock);
+  lock_unlock (dfa->lock);
   return rval;
 }
 

--- a/modules/lock
+++ b/modules/lock
@@ -11,6 +11,7 @@
 
 configure.ac:
 gl_LOCK
+gl_MODULE_INDICATOR([lock])
 
 Makefile.am:
 lib_SOURCES += glthread/lock.h glthread/lock.c

--- a/modules/pthread
+++ b/modules/pthread
@@ -13,6 +13,7 @@
 
 configure.ac:
 gl_PTHREAD_CHECK
+gl_MODULE_INDICATOR([pthread])
 
 Makefile.am:
 BUILT_SOURCES += $(PTHREAD_H)

--- a/modules/regex
+++ b/modules/regex
@@ -24,7 +24,6 @@
 mbrtowc         [test $ac_use_included_regex = yes]
 mbsinit         [test $ac_use_included_regex = yes]
 nl_langinfo     [test $ac_use_included_regex = yes]
-pthread         [test $ac_use_included_regex = yes]
 stdbool         [test $ac_use_included_regex = yes]
 stdint          [test $ac_use_included_regex = yes]
 wchar           [test $ac_use_included_regex = yes]