Re: [PATCH trace-cmd 3/3] Revert "trace-cmd: Use conditional assignmentof CC and AR"

[Darren Hart]

On 03/09/2011 09:25 PM, David Sharp wrote:
> On Wed, Mar 9, 2011 at 7:26 PM, Steven Rostedt<rostedt@xxxxxxxxxxx>  wrote:
> > On Wed, 2011-03-09 at 21:51 -0500, Steven Rostedt wrote:
> >
> > > I'll play with some other make tricks and see if I can come up with a
> > > better solution.
> >
> > OK, it didn't take me long to come up with "Makefiles suck" ;)
>
> Yes, except for very basic things.
>
> > But I did come up with a solution:
> >
> > ifneq ("$(origin CC)", "environment")
> > CC = gcc
> > endif
> >
> > CC := $(CROSS_COMPILE)$(CC)
> >
> > This wont let make CC=xx work unless I also add a:
> >
> > ifneq ("$(origin CC)", "command line")
> >
> > around the above if, but do we care?
> >
> > -- Steve
>
> 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:

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?

--
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel
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