Re: pattern rules

[Ralf Wildenhues]

* Ralf Hemmecke wrote on Thu, Mar 27, 2008 at 01:31:36PM CET:
>
> -W CATEGORY
> --warnings=category
>     Output warnings falling in category. category can be one of:
>     ...
>     portability
>         portability issues (e.g., use of make features that are
>         known to be not portable)
>
> ---END quote
>
> It is not so clear what this relates to. Is it only related to the  
> 'make' program or also some portability issues outside of it?

Hmm, the documentation doesn't specify this well.  Currently, most
issues which are warned about revolve around 'make' issues.  But there
are also a couple of others:
- that you may need AM_PROG_CC_C_O if '-c -o' is used in build rules,
- that directory names like 'aux' or 'obj' are not portable.

> In other words, can I simply say "no-portability" and don't relax
> strictness in places not related to GNU make features?

What you can do is use -Wno-portability only for those Makefile.am files
for which you need it, by enabling it in those files only:
  AUTOMAKE_OPTIONS = ... -Wno-portability

So there are two items where Automake could be improved here:
- document exactly the semantics of which options are applied
  (when they are passed in more than one place: on the automake command
  line, in AM_INIT_AUTOMAKE, and in per-file AUTOMAKE_OPTIONS),
- document which portability issues are warned about with -Wportability,
  or possibly even split this into separate categories.

Discussions and patches welcome.

Cheers,
Ralf