Re: readline does not compile anymore on HP-UX since d5f26b1287916c1790323965d46f5e0acad89155

[Osipov, Michael (LDA IT PLM)]

Am 2021-08-17 um 15:11 schrieb Chet Ramey:
> On 8/17/21 6:36 AM, Osipov, Michael (LDA IT PLM) wrote:
> > Folks,
> >
> > > +if test -n "$want_auto_cflags" ; then
> > > +    AUTO_CFLAGS="-g ${GCC+-O2}"
> > > +    STYLE_CFLAGS="${GCC+-Wno-parentheses} ${GCC+-Wno-format-security}"
> > > +fi
> >
> > This hunks seems not to be POSIX shell compliant.
>
> It's absolutely POSIX shell compliant.
>
> > Both vars are set for me
> > on HP-UX because the expansion is incomplete.
>
> The expansion is not incomplete. The gcc-specific options will be set if
> the GCC variable has a value.
>
>   According to [1] it has to be
> > $(GCC:+..} and not $(GCC+..}.
>
> POSIX does not say that. What it says is:
>
> "In the parameter expansions shown previously, use of the <colon> in the
> format shall result in a test for a parameter that is unset or null;
> omission of the <colon> shall result in a test for a parameter that is only
> unset. "
>
>
> > I have changed ./configure locally and it
> > works with /bin/sh.
>
> It sounds like you've found a bug in the HP-UX sh.
>
> > I assume that this should also work on any other POSIX compliant shell.
>
> It doesn't mean the same thing. Maybe you should try adding a space between
> the `+' and `-' to get around the sh bug.

Darn! Chet, you are absolutely right. According to the manpage of sh(1) 
on HP-Ux is is supposed to be POSIX compliant:
>       ${parameter:+word}
>                      If parameter is set and is nonnull, substitute word;
>                      otherwise, substitute nothing.
...
>       If the colon (:) is omitted from the above expressions, the shell only
>       checks to determine whether or not parameter is set.

But is still logically doesn't add up. From ./configure:
> if test $ac_compiler_gnu = yes; then
>   GCC=yes
> else
>   GCC=
> fi

So the variable is *always* set. Thus word is always substituted. I 
would expect no else branch in the if clause then I would competely 
agree with Chet. Removing the else block makes the sript works as expected.

What am I missing here?

Michael