Re: trouble with order rules in implicit rules

[Noel Yap]

I think I've got it (de ja vu, actually, I think I ran into this some time ago 
and came to the same conclusion):  Don't use order rules in implicit rules.  
Rather, use order rules only in static rules.

If I change the makefile to:

.PHONY: install
install: foo/bar/baz

.PRECIOUS: %/.
%/.:
        mkdir -p $(@)

foo/%: ./%
        @echo $(<)
        touch $(@)

foo/bar/%: bar/%
        @echo $(<)
        touch $(@)

foo/bar/baz: | foo/bar/.

bar/baz:


everything works perfectly.  This sounds to me, though, that there's still a 
bug lurking somewhere.

Noel

Noel Yap wrote:
> I think I see.  If I switch the two rules and foo doesn't exist, 
> everything works fine.  But if foo exists and foo/bar doesn't, the same 
> error occurs even if the rule for foo/bar/% comes first.  If this is the 
> defined behaviour, what needs to be done to get the action to be fired 
> in the latter scenario?
>
> Thanks,
> Noel
>
> Paul D. Smith wrote:
>
> > %% Noel Yap <address@hidden> writes:
> >
> >   ny> I had thought that the better-matching rule would be the one used.
> >
> > I don't know what "better-matching" means, but the way make chooses a
> > pattern rule is well-defined; from section "Introduction to Pattern
> > Rules":
> >
> >
> > >   The order in which pattern rules appear in the makefile is important
> > > since this is the order in which they are considered.  Of equally
> > > applicable rules, only the first one found is used.
> >
> >
> >
> > I guess that's a little confusing, since "equally applicable" isn't
> > defined anywhere.  But, it refers to the last sentence:
> >
> >
> > > Note however, that a rule whose prerequisites actually exist or are
> > > mentioned always takes priority over a rule with prerequisites that must
> > > be made by chaining other implicit rules.
> >
> >
> >
> >
> > Anyway, the short answer is that for basic pattern rules (not chained
> > pattern rules) the first one appearing in the makefile is always used.
>
>
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