Re: POSIXLY_CORRECT not correctly unset in getopt.m4?

[Paolo Bonzini]

On 09/08/2010 11:30 AM, Bruno Haible wrote:
> [removing bug-standards from the CC list]
>
> 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.
>
> But it handles an empty exported value correctly:
>    export POSIXLY_CORRECT=
> has the same semantics as
>    export POSIXLY_CORRECT=1

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

bash seems to confirm this

    $ POSIXLY_CORRECT=
    $ set -o | grep posix
    posix               on
    $ echo ${POSIXLY_CORRECT:+yes}

    $ echo ${POSIXLY_CORRECT+yes}
    yes

Paolo