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

[Alexey Neyman]

On 03/11/2017 05:53 PM, Mike Frysinger wrote:

> On 09 Mar 2017 13:50, 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
> why not just use an ERE then ?
> 	if $READELF -S conftest.so | grep -E '\.rela?\.dyn' >/dev/null; then
>
> it's not clear what standard glibc is attempting to adhere to, but it
> seems like we should just permit whatever is in POSIX.  i.e. replace
> all the /dev/null redirects with a -q flag.
-F is POSIX, too, so either works.

I'll update the patch to use -q once you settle on whether -E or -F is 
preferred :)

Regards,
Alexey.