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Re: A question on implicit rules

From: Paolo Gai
Subject: Re: A question on implicit rules
Date: Wed, 11 Feb 2004 16:16:12 +0100

> [...]
> > begin----------------------------
> > A%: B/C%D
> >         @echo A$*
> > 
> > B/C%D:
> >         @echo B/C$*D
> > end----------------------------
> ['make A2' does what you'd expect. But if you delete
> the command for the A% rule, it says:]
> > make: *** No rule to make target `A2'.  Stop.
> I think this is equivalent to the simpler case of
> a makefile that contains only this line:
> A%:
> when no file 'A2' exists.

> Then shouldn't 'make A2' fail, because there's no command
> for make to update file 'A2'? What behavior would be better?

In general, I think the rule "A2" with no prerequisites and no commands
should fail.

Actually I'm using the rule A% like a phony target, the thing is that I
cannot declare it as ".PHONY". the A% has a prerequisite, and I would
like that it executes it in some way...

I'll try to explain better:

consider this makefile:

OPTIONLIST_A = opt_a1 opt_a1
OPTIONLIST_B = opt_b1 opt_b2

MYLIST_WITHPREFIX = $(addprefix prefix_, $(MYLIST))
prefix_% : myfile_%
        @echo why??
myfile_% :
        echo command with parameter $($*) > $@

Typing "make", I would expect rule "all" would be executed .

To make "all", rules prefix_OPTIONLIST_A and prefix_OPTIONLIST_B would
be considered.

finally, to make for example prefix_OPTIONLIST_A, the rule
myfile_OPTIONLIST_A should be executed

The outputs on my machine are the following:

if I run just "make", I obtain:

address@hidden m]$ make
echo command with parameter opt_a1 opt_a1 > myfile_OPTIONLIST_A
echo command with parameter opt_b1 opt_b2 > myfile_OPTIONLIST_B
address@hidden m]$

anyone can explain why "rm myfile_OPTIONLIST_A myfile_OPTIONLIST_B",
since no "rm" statements are inside the makefile?

with the line "@echo why??" commented with an "#", I have:

address@hidden m]$ make
make: *** No rule to make target `prefix_OPTIONLIST_A', needed by
`all'.  Stop.
address@hidden m]$

I initally had this spurius "rm", and I thought that the problem was
related to the use of "%", as said in the first mail. But probably it is
something else?

Thanks for all,


Paolo Gai - ReTiS Lab - PhD Student

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