Re: Bug in pattern rule parsing: how to handle?

[Sam Ravnborg]

On Wed, Oct 29, 2008 at 07:24:50PM -0700, Philip Guenther wrote:
> On Wed, Oct 29, 2008 at 2:12 PM, Sam Ravnborg <address@hidden> wrote:
> > On Sun, Oct 26, 2008 at 07:12:53PM -0400, Paul Smith wrote:
> ...
> >>         Makefile:442: *** mixed implicit and normal rules.  Stop.
> >>
> >>         config %config: scripts_basic outputmakefile FORCE
> >>                 $(Q)mkdir -p include/linux include/config
> >>                 $(Q)$(MAKE) $(build)=scripts/kconfig $@
> >
> > Here I try to catch the following:
> >
> > make config
> > make menuconfig
> > make xconfig
> > make foobarconfig
> >
> > I must admit I cannot see the problem with mixing implicit and normal
> > rules in the above. But I gues this is my simple use of it.
> 
> I see at least two ways in which it's confusing:
> 1) what prerequisites does "foo" have with this rule:
>     foo %.c: %.c.real
>         @: cp $< $@
> 
> 2) rules with multiple pattern targets have special meaning to make:
>        Pattern rules may have more than one target.  Unlike normal rules,
>        this does not act as many different rules with the same prerequisites
>        and commands.  If a pattern rule has multiple targets, `make' knows 
> that
>        the rule's commands are responsible for making all of the targets.  
> <...>
>     I.e., this rule:
>     %.a %.b:
>         ${commands}
>     says that building "bar.a" will also build "bar.b", and
>     building "quux.a" will also build "quux.b".  With this rule:
>     foo %.a %.b:
>         ${commands}
>     should make assume that building "bar.a" will also build "bar.b"
> *and* "foo"?
>     How about this rule:
>     foo blip %.a %.b:
>         ${commands}
>     Will building "bar.a" also build "bar.b", "foo", and "blip"?
>     How about this one:
>     foo blip %.a:
>         ${commands}
>     ...whoops...

Thanks for the detailed explanation. I see how it is confusing in
the cases you list. I was initally wondering because the specific
usage in the kernel is simpler.

> 
> 
> > Do you have any god suggestion how to rewrite this?

[suggestions snipped]

Thanks. I will most likely do something along the lines of the last
suggestion.

        Sam