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

[Mike Frysinger]

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.
-mike
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