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

From: Darren Hart
Date: Thu Mar 10 2011 - 01:46:21 EST


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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