From ac2121bf962ecc054dd103ccd42a93912051672e Mon Sep 17 00:00:00 2001
From: Kamil Dudka <kdudka@redhat.com>
Date: Tue, 21 Jun 2016 12:40:26 +0200
Subject: [PATCH] curl-compilers.m4: improve detection of GCC's -fvisibility=
 flag

Some builds of GCC produce output on both stdout and stderr when --help
--verbose is used.  The 2>&1 redirection caused them to be arbitrarily
interleaved with each other because of stream buffering.  Consequently,
grep failed to match the fvisibility= string in the mixed output, even
though the string was present in GCC's standard output.

This led to silently disabling symbol hiding in some builds of curl.

Upstream-commit: b2dcf0347f1ee5041cccd64632bb8dd7ccbbae91
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
 configure            | 2 +-
 m4/curl-compilers.m4 | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/configure b/configure
index 4797e02..fc260ee 100755
--- a/configure
+++ b/configure
@@ -17636,7 +17636,7 @@ $as_echo_n "checking if compiler supports hiding library internal symbols... " >
       ;;
     GNU_C)
             if test "$compiler_num" -ge "304"; then
-        if $CC --help --verbose 2>&1 | grep fvisibility= > /dev/null ; then
+        if $CC --help --verbose 2>/dev/null | grep fvisibility= >/dev/null ; then
           tmp_EXTERN="__attribute__ ((__visibility__ (\"default\")))"
           tmp_CFLAGS="-fvisibility=hidden"
           supports_symbol_hiding="yes"
diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
index ca064dd..77371de 100644
--- a/m4/curl-compilers.m4
+++ b/m4/curl-compilers.m4
@@ -21,7 +21,7 @@
 #***************************************************************************
 
 # File version for 'aclocal' use. Keep it a single number.
-# serial 65
+# serial 66
 
 
 dnl CURL_CHECK_COMPILER
@@ -1391,7 +1391,7 @@ AC_DEFUN([CURL_CHECK_COMPILER_SYMBOL_HIDING], [
     GNU_C)
       dnl Only gcc 3.4 or later
       if test "$compiler_num" -ge "304"; then
-        if $CC --help --verbose 2>&1 | grep fvisibility= > /dev/null ; then
+        if $CC --help --verbose 2>/dev/null | grep fvisibility= >/dev/null ; then
           tmp_EXTERN="__attribute__ ((__visibility__ (\"default\")))"
           tmp_CFLAGS="-fvisibility=hidden"
           supports_symbol_hiding="yes"
-- 
2.5.5