Re: Detecting Autoconf and Including Additional M4 Files

[Christopher Key]

Eric Blake wrote:
> According to Christopher Key on 9/24/2007 5:15 AM:
>   
> > Hence, what I'd like to do is to be able to
> > detect whether autoconf has been used, and act appropriately
> >     
>
> Why not just a simple AC_DEFINE using a macro name of your choice, that
> you know will not be injected into your compilation if you didn't run
> autoconf?
>
>   
Will do, I just didn't want to reinvent the wheel!  Had there been a 
standard way of doing this (or a standard name for the define), I'd have 
used it to make life easier for folks trying to understand what I'd done.
> > Secondly, I'm also wanting to detect whether there an arithmetic right
> > shift available.  I've found a test that does this, and have put it in
> > package/m4/asr.m4.  What I'm wondering is how to ensure that this file
> > is included.  The only way I've found to achieve this is to add
> > 'ACLOCAL_AMFLAGS = -I m4' to package/Makefile.am, but this doesn't seem
> > quite right.
> >     
>
> Actually, it is the documented way to do things if you use both autoconf
> and automake.
>
>   
I'll have to reread the various guides again, as at the moment, this 
seems rather counter-intuitive to me.  Conceptually, the way that I had 
seen the system working was that configure.ac is 'run', producing 
configure as an ouput, and taking Makefile.am as 'inputs' and producing 
corresponding Makefile.in as outputs.  As asr.m4 is a 'dependency' of 
configure.ac, it seems like it should be 'included' from configure.ac 
itself, and not one of its inputs.


Regards,

Chris