Re: POSIXLY_CORRECT not correctly unset in getopt.m4?

[Eric Blake]

On 09/08/2010 03:56 AM, Paolo Bonzini wrote:
> On 09/08/2010 11:30 AM, Bruno Haible wrote:
> > Paolo Bonzini wrote:
> > > On 09/07/2010 10:39 PM, Eric Blake wrote:
> > > > gl_awk_probe='BEGIN { for (v in ENVIRON)
> > > > if (v == "POSIXLY_CORRECT") print "x" }'
> > > > case ${POSIXLY_CORRECT:+x}`awk "$gl_awk_probe"</dev/null` in
> > > > xx) gl_had_POSIXLY_CORRECT=exported ;;
> > > > x) gl_had_POSIXLY_CORRECT=yes ;;
> > > > *) gl_had_POSIXLY_CORRECT= ;;
> > > > esac
> > >
> > > Walking all of ENVIRON seems slow.

Then we should be able to use the faster:

if ("POSIXLY_CORRECT" in ENVIRON)

Autoconf documents that traditional awk has 'for (a in b)' but lacks 'if 
(a in b)'; but we are already avoiding traditional awk for their lack of 
ENVIRON, and all the [gmn]awk implementations I tested support both forms.

> So maybe it should be ${POSIXLY_CORRECT+x}, not ${POSIXLY_CORRECT:+x}?
> Right now it's inconsistent.

Good catch.  I'm installing a fix for that:

diff --git i/ChangeLog w/ChangeLog
index 103ab6c..2daedad 100644
--- i/ChangeLog
+++ w/ChangeLog
@@ -1,3 +1,10 @@
+2010-09-08  Eric Blake  <address@hidden>
+
+       getopt: optimize previous patch
+       * m4/getopt.m4 (gl_GETOPT_CHECK_HEADERS): Correctly check for
+       empty variable.  Speed up awk script.
+       Reported by Paolo Bonzini.
+
 2010-09-07  Eric Blake  <address@hidden>

        strtod: work around IRIX 6.5 bug
diff --git i/m4/getopt.m4 w/m4/getopt.m4
index 720f048..d05e9d9 100644
--- i/m4/getopt.m4
+++ w/m4/getopt.m4
@@ -1,4 +1,4 @@
-# getopt.m4 serial 30
+# getopt.m4 serial 31
 dnl Copyright (C) 2002-2006, 2008-2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -218,9 +218,8 @@ main ()
        # so take care to revert to the correct (non-)export state.
 dnl GNU Coding Standards currently allow awk but not env; besides, env
 dnl is ambiguous with environment values that contain newlines.
-       gl_awk_probe='BEGIN { for (v in ENVIRON)
-         if (v == "POSIXLY_CORRECT") print "x" }'
-       case ${POSIXLY_CORRECT:+x}`$AWK "$gl_awk_probe" </dev/null` in
+       gl_awk_probe='BEGIN { if ("POSIXLY_CORRECT" in ENVIRON) print "x" }'
+       case ${POSIXLY_CORRECT+x}`$AWK "$gl_awk_probe" </dev/null` in
          xx) gl_had_POSIXLY_CORRECT=exported ;;
          x)  gl_had_POSIXLY_CORRECT=yes      ;;
          *)  gl_had_POSIXLY_CORRECT=         ;;


--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org