--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2014-09-04  Paul Eggert  <eggert@cs.ucla.edu>
+
+	pthread, pthread_sigmask, threadlib: port to Ubuntu 14.04
+	Problem reported by Assaf Gordon in:
+	http://lists.gnu.org/archive/html/bug-gnulib/2014-09/msg00023.html
+	Apparently Ubuntu is doing some fancy link-time optimization
+	that doesn't work with -lpthread but does work with -pthread.
+	Work around the bug by preferring -pthread to -lpthread.
+	* m4/pthread.m4 (gl_PTHREAD_CHECK):
+	* m4/threadlib.m4 (gl_THREADLIB_BODY): Prefer -pthread to -lpthread.
+	* m4/pthread_sigmask.m4 (gl_FUNC_PTHREAD_SIGMASK):
+	Treat -pthread like -lpthread.
+
 2014-09-04  Eric Blake  <eblake@redhat.com>
 
 	error: drop spurious semicolon

--- a/m4/pthread.m4
+++ b/m4/pthread.m4
@@ -1,4 +1,4 @@
-# pthread.m4 serial 8
+# pthread.m4 serial 9
 dnl Copyright (C) 2009-2014 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -63,7 +63,7 @@
        [gl_cv_lib_pthread],
        [gl_saved_libs=$LIBS
         gl_cv_lib_pthread=
-        for gl_lib_prefix in '' '-lpthread'; do
+        for gl_lib_prefix in '' '-pthread' '-lpthread'; do
           LIBS="$gl_lib_prefix $gl_saved_libs"
           AC_LINK_IFELSE(
             [AC_LANG_PROGRAM(

--- a/m4/pthread_sigmask.m4
+++ b/m4/pthread_sigmask.m4
@@ -1,4 +1,4 @@
-# pthread_sigmask.m4 serial 14
+# pthread_sigmask.m4 serial 15
 dnl Copyright (C) 2011-2014 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -40,7 +40,7 @@
              LIBS="$gl_save_LIBS"
             ])
           if test $gl_cv_func_pthread_sigmask_in_LIBMULTITHREAD = yes; then
-            dnl pthread_sigmask is available with -lpthread.
+            dnl pthread_sigmask is available with -pthread or -lpthread.
             LIB_PTHREAD_SIGMASK="$LIBMULTITHREAD"
           else
             dnl pthread_sigmask is not available at all.
@@ -86,7 +86,7 @@
   AC_SUBST([LIB_PTHREAD_SIGMASK])
   dnl We don't need a variable LTLIB_PTHREAD_SIGMASK, because when
   dnl "$gl_threads_api" = posix, $LTLIBMULTITHREAD and $LIBMULTITHREAD are the
-  dnl same: either both empty or both "-lpthread".
+  dnl same.
 
   dnl Now test for some bugs in the system function.
   if test $HAVE_PTHREAD_SIGMASK = 1; then
@@ -98,6 +98,7 @@
     dnl no effect.
     if test -z "$LIB_PTHREAD_SIGMASK"; then
       case " $LIBS " in
+        *' -pthread '*) ;;
         *' -lpthread '*) ;;
 	*)
 	  AC_CACHE_CHECK([whether pthread_sigmask works without -lpthread],

--- a/m4/threadlib.m4
+++ b/m4/threadlib.m4
@@ -1,4 +1,4 @@
-# threadlib.m4 serial 10 (gettext-0.18.2)
+# threadlib.m4 serial 11 (gettext-0.18.2)
 dnl Copyright (C) 2005-2014 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -22,7 +22,7 @@
 dnl Sets the variables LIBMULTITHREAD and LTLIBMULTITHREAD similarly, for
 dnl programs that really need multithread functionality. The difference
 dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak
-dnl symbols, typically LIBTHREAD="" whereas LIBMULTITHREAD="-lpthread".
+dnl symbols, typically LIBTHREAD is empty whereas LIBMULTITHREAD is not.
 dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
 dnl multithread-safe programs.
 
@@ -162,15 +162,31 @@
         # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
         # in libc. IRIX 6.5 has the first one in both libc and libpthread, but
         # the second one only in libpthread, and lock.c needs it.
-        AC_LINK_IFELSE(
-          [AC_LANG_PROGRAM(
-             [[#include <pthread.h>]],
-             [[pthread_mutex_lock((pthread_mutex_t*)0);
-               pthread_mutexattr_init((pthread_mutexattr_t*)0);]])],
-          [gl_have_pthread=yes])
+        #
+        # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04
+        # needs -pthread for some reason.  See:
+        # http://lists.gnu.org/archive/html/bug-gnulib/2014-09/msg00023.html
+        save_LIBS=$LIBS
+        for gl_pthread in '' '-pthread'; do
+          LIBS="$LIBS $gl_pthread"
+          AC_LINK_IFELSE(
+            [AC_LANG_PROGRAM(
+               [[#include <pthread.h>
+                 pthread_mutex_t m;
+                 pthread_mutexattr_t ma;
+               ]],
+               [[pthread_mutex_lock (&m);
+                 pthread_mutexattr_init (&ma);]])],
+            [gl_have_pthread=yes
+             LIBTHREAD=$gl_pthread LTLIBTHREAD=$gl_pthread
+             LIBMULTITHREAD=$gl_pthread LTLIBMULTITHREAD=$gl_pthread])
+          LIBS=$save_LIBS
+          test -n "$gl_have_pthread" && break
+        done
+
         # Test for libpthread by looking for pthread_kill. (Not pthread_self,
         # since it is defined as a macro on OSF/1.)
-        if test -n "$gl_have_pthread"; then
+        if test -n "$gl_have_pthread" && test -z "$LIBTHREAD"; then
           # The program links fine without libpthread. But it may actually
           # need to link with libpthread in order to create multiple threads.
           AC_CHECK_LIB([pthread], [pthread_kill],
@@ -185,7 +201,7 @@
                    [Define if the pthread_in_use() detection is hard.])
              esac
             ])
-        else
+        elif test -z "$gl_have_pthread"; then
           # Some library is needed. Try libpthread and libc_r.
           AC_CHECK_LIB([pthread], [pthread_kill],
             [gl_have_pthread=yes
@@ -326,6 +342,8 @@
 dnl
 dnl GNU Hurd/glibc     posix
 dnl
+dnl Ubuntu 14.04       posix      -pthread        Y      OK
+dnl
 dnl FreeBSD 5.3        posix      -lc_r           Y
 dnl                    posix      -lkse ?         Y
 dnl                    posix      -lpthread ?     Y