Subject: Re: [PATCH trace-cmd 3/3] Revert "trace-cmd: Use conditional
 assignment of CC and AR"
From: Steven Rostedt <rostedt@goodmis.org>
To: Darren Hart <dvhart@linux.intel.com>
Cc: David Sharp <dhsharp@google.com>, linux-kernel@vger.kernel.org,
        mrubin@google.com
In-Reply-To: <4D7873B5.7090602@linux.intel.com>
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Date: Thu, 10 Mar 2011 08:02:42 -0500
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On Wed, 2011-03-09 at 22:46 -0800, Darren Hart wrote:

> > This seems to do it all:
> >
> > define allow-override
> >    $(if $(or $(findstring environment,$(origin $(1))),
> >              $(findstring command line,$(origin $(1)))),,\
> >      $(eval $(1) = $(2)))
> > endef
> >
> > $(call allow-override,CC,$(CROSS_COMPILE)gcc)
> > $(call allow-override,AR,$(CROSS_COMPILE)ar)
> 
> Egads .... that's hideous :-) This level of complexity makes it very 
> difficult for people to readily understand it. What does this offer over:

Love the world of makefiles ;) Nothing that comments wont solve.

> 
> ifdef CROSS_COMPILE
> CC = $(CROSS_COMPILE)gcc
> AR = $(CROSS_COMPILE)ar
> endif
> 
> besides being 3 lines longer with much more complex Makefile syntax and 
> conditional statements?

Yes, the above is simple and solves the issue for both you and David,
but it has a side-effect that David already pointed out. CC is now cc
and not gcc. I don't like that, as I do have systems that cc is
different that gcc and I want to use gcc.

But if I define CROSS_COMPILE it then suddenly uses gcc. Yes this may
not seem like a big deal now, but in the future, it could cause a lot of
headache. I rather have the more complex yet correct solution that is
consistent than a simple easy to read solution with a subtle side-effect
that is hidden.

-- Steve


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