>From 9c42aee8fe88c4dfe6b6e60e1570aac759829b4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A1draig=20Brady?= <address@hidden>
Date: Fri, 13 Jun 2014 19:56:20 +0100
Subject: [PATCH] pthread: define thread safe macros on some platforms

* m4/pthread.m4 (gl_PTHREAD_CHECK): When not using the
threadlib module, which otherwise handles this, define
macros needed for thread safe access on some platforms.
---
 ChangeLog     |    7 +++++++
 m4/pthread.m4 |   24 ++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index cd19897..10c43d3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2014-06-13  Pádraig Brady  <address@hidden>
+
+	pthread: define thread safe macros on some platforms
+	* m4/pthread.m4 (gl_PTHREAD_CHECK): When not using the
+	threadlib module, which otherwise handles this, define
+	macros needed for thread safe access on some platforms.
+
 2014-06-13  Paul Eggert  <address@hidden>
 
 	regex: don't be multithreaded if USE_UNLOCKED_IO.
diff --git a/m4/pthread.m4 b/m4/pthread.m4
index 1ed0dd3..9288d59 100644
--- a/m4/pthread.m4
+++ b/m4/pthread.m4
@@ -88,6 +88,30 @@ AC_DEFUN([gl_PTHREAD_CHECK],
    fi
    AC_SUBST([LIB_PTHREAD])
 
+   dnl If the threadlib module isn't selected then setup
+   dnl macros to enable threadsafe operation on some platforms
+   if test x"$gl_use_threads" = x; then
+     # For using <pthread.h>:
+     case "$host_os" in
+       osf*)
+         # On OSF/1, the compiler needs the flag -D_REENTRANT so that it
+         # groks <pthread.h>. cc also understands the flag -pthread, but
+         # we don't use it because 1. gcc-2.95 doesn't understand -pthread,
+         # 2. putting a flag into CPPFLAGS that has an effect on the linker
+         # causes the AC_LINK_IFELSE test below to succeed unexpectedly,
+         # leading to wrong values of LIBTHREAD and LTLIBTHREAD.
+         CPPFLAGS="$CPPFLAGS -D_REENTRANT"
+         ;;
+     esac
+     # Some systems optimize for single-threaded programs by default, and
+     # need special flags to disable these optimizations. For example, the
+     # definition of 'errno' in <errno.h>.
+     case "$host_os" in
+       aix* | freebsd*) CPPFLAGS="$CPPFLAGS -D_THREAD_SAFE" ;;
+       solaris*) CPPFLAGS="$CPPFLAGS -D_REENTRANT" ;;
+     esac
+   fi
+
    AC_REQUIRE([AC_C_RESTRICT])
 ])
 
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1.7.7.6