Re: Empty else part in AS_IF

[Julien ÉLIE]

Hi Eric,

First of all, thanks for your answer.


> >   AS_IF([test x"$var" != xfalse],
> >       [$test=1],
> >       [m4_ifdef([AM_CONDITIONAL],
> >           [AM_CONDITIONAL([TEST], [false])])])
> >
> > gives the following configure code with autoconf 2.69:
> >
> >   if test x"$var" != xfalse; then :
> >    $test=1
>
> That's unusual shell syntax (it does NOT do a variable assignment; did
> you mean 'test=1' instead of trying to execute the program whose name is
> the expansion of $test concatenated with '=1'?)

Yes, you're right.  I meant to write "test=1" in the provided sample.
We have a far more complex m4 file (used for INN, a news server), and I 
just wanted to provide a minimal AS_IF to explain what I was facing.

It is the reason why the error I quoted from configure is at line 23581 :)

./configure: line 23581: syntax error near unexpected token `fi'
./configure: line 23581: `fi'



> > else
> >
> > fi
> >
> > which is not a valid syntax.
>
> Indeed.  The problem is that autoconf cannot tell if a non-empty literal
> will expand to empty text (m4_ifdef results in no output).  You'll have
> to workaround it yourself:
>
> AS_IF([test x"$var" != xfalse],
>      [$test=1],
>      [: m4_ifdef(...)])

Thanks for the suggestion of [: m4_ifdef(...)].  It looks prettier than 
adding [:] in the arguments of m4_ifdef.

Have a nice week,

--
Julien ÉLIE

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