From 58d05b2a57802345f43e628bc0807dbf0116cdcc Mon Sep 17 00:00:00 2001
From: Max Filippov <jcmvbkbc@gmail.com>
Date: Fri, 20 Mar 2015 16:37:51 +0300
Subject: [PATCH] Compare linker/compiler output with their default output

linker and compiler may have noisy output by default, making
acx_pthread.m4 believe that pthread options that it tries are ignored
as invalid.

Record default compiler and linker output and see if adding pthread
option changes that, instead of assuming that linker and compiler are
silent by default.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 config/acx_pthread.m4 | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/config/acx_pthread.m4 b/config/acx_pthread.m4
index 581164b..d254612 100644
--- a/config/acx_pthread.m4
+++ b/config/acx_pthread.m4
@@ -80,6 +80,22 @@
 esac
 
 if test x"$acx_pthread_ok" = xno; then
+
+cat >conftest.$ac_ext <<_ACEOF
+int
+main (int argc, char **argv)
+{
+  (void) argc;
+  (void) argv;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+
+# Record the default linker and compiler output
+ld_default_output="`(eval $ac_link 2>&1 1>&5)`"
+cc_default_output="`(eval $ac_compile 2>&1 1>&5)`"
+
 for flag in $acx_pthread_flags; do
 
         tryPTHREAD_CFLAGS=""
@@ -143,7 +159,7 @@
 _ACEOF
             rm -f conftest.$ac_objext conftest$ac_exeext
             # Check both linking and compiling, because they might tolerate different options.
-            if test "`(eval $ac_link 2>&1 1>&5)`" = "" && test "`(eval $ac_compile 2>&1 1>&5)`" = ""; then
+            if test "`(eval $ac_link 2>&1 1>&5)`" = "$ld_default_output" && test "`(eval $ac_compile 2>&1 1>&5)`" = "$cc_default_output"; then
                 # we continue with more flags because Linux needs -lpthread
                 # for libpq builds on PostgreSQL.  The test above only
                 # tests for building binaries, not shared libraries.
-- 
1.8.1.4