[PATCH v2] configure.ac: Avoid empty subexpression in grep

[Alexey Neyman <stilor at att dot net>]

On 03/09/2017 01:50 PM, Paul Eggert wrote:
> On 03/09/2017 08:12 AM, Alexey Neyman wrote:
> > -  if $READELF -S conftest.so | grep '\.rel\(a\|\)\.dyn' > /dev/null; 
> > then
> > +  if $READELF -S conftest.so | grep '\.\(rel\|rela\)\.dyn' > 
> > /dev/null; then
>
> Neither the old nor the new code is portable, as POSIX does not 
> require support for '\|'. Instead, how about something like this?
>
>    if $READELF -S conftest.so | grep -F -e '.rel.dyn' -e '.rela.dyn' > 
> /dev/null; then

Yes, that works too. Updated patch attached.

Regards,
Alexey.

>From 9b19fc80fc48c3b24e10cf4a190a74e35f4371cc Mon Sep 17 00:00:00 2001
From: Alexey Neyman <stilor@att.net>
Date: Wed, 8 Mar 2017 14:31:10 -0800
Subject: [PATCH v2] Fix combreloc test with BSD grep

The test for "-z combreloc" fails when cross-compiling on a machine
that uses BSD grep (e.g. on macos). grep complains about empty
subexpression and exits with non-zero status, which is interpreted
by configure as "not found". As a result, support for "-z combreloc"
(HAVE_Z_COMBRELOC) is not detected, leading to link failure on SPARC.

	* configure.ac: Avoid empty subexpression in grep.

Signed-off-by: Alexey Neyman <stilor@att.net>
---
 ChangeLog    | 5 +++++
 configure    | 2 +-
 configure.ac | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index ba57667..0ed7d3d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2017-03-08  Alexey Neyman <stilor@att.net>
+
+	* configure.ac: Avoid empty subexpression in grep.
+	* configure: Regenerate.
+
 2017-03-08  Yury Norov <ynorov@caviumnetworks.com>
 	    Zack Weinberg  <zackw@panix.com>
 
diff --git a/configure.ac b/configure.ac
index 4a77411..19f6d87 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1391,7 +1391,7 @@ dnl cross-platform since the gcc used can be a cross compiler.  Without
 dnl introducing new options this is not easily doable.  Instead use a tool
 dnl which always is cross-platform: readelf.  To detect whether -z combreloc
 dnl look for a section named .rel.dyn.
-  if $READELF -S conftest.so | grep '\.rel\(a\|\)\.dyn' > /dev/null; then
+  if $READELF -S conftest.so | grep '\.\(rel\|rela\)\.dyn' > /dev/null; then
     libc_cv_z_combreloc=yes
   else
     libc_cv_z_combreloc=no
-- 
2.9.3