Re: [Qemu-devel] Re: [PATCH 70/81] remove last 3 uses of :=, everywhere else uses += or =

[Hollis Blanchard <hollis@penguinppc.org>]

On Wed, Aug 26, 2009 at 2:46 PM, Juan Quintela<quintela@redhat.com> wrote:
> Hollis Blanchard <hollis@penguinppc.org> wrote:
>> On Mon, Aug 3, 2009 at 5:47 AM, Juan Quintela<quintela@redhat.com> wrote:
>>>
>>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>>> ---
>>>  Makefile.target |    6 +++---
>>>  1 files changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/Makefile.target b/Makefile.target
>>> index a4d269d..6b3d40f 100644
>>> --- a/Makefile.target
>>> +++ b/Makefile.target
>>> @@ -20,7 +20,7 @@ endif
>>>  PROGS=$(QEMU_PROG)
>>>
>>>  ifeq ($(subst ppc64,ppc,$(ARCH))$(TARGET_BASE_ARCH),ppcppc)
>>> -translate.o: QEMU_CFLAGS := $(QEMU_CFLAGS) $(call cc-option, $(QEMU_CFLAGS), -fno-unit-at-a-time,)
>>> +translate.o: QEMU_CFLAGS += $(call cc-option, $(QEMU_CFLAGS), -fno-unit-at-a-time,)
>>>  endif
>>>
>>>  LIBS+=-lm
>>
>> This change breaks the build with PPC host and PPC target:
>> Makefile:25: *** Recursive variable `QEMU_CFLAGS' references itself
>> (eventually).  Stop.
>>
>> I don't know why you want to remove all :=, but it seems like this
>> hunk should be reverted.
>
> Could you check two things:
>
> a- remove the whole block, it should not be needed anymore (or that I
>   have been told)

The original commit, from malc, says it's necessary to work around a
gcc 4.3.0 bug. If that's true, it's probably not a great idea to
remove it.

> b- if a) don't work, tryng to change the interior bit to
>
> translate.o: QEMU_CFLAGS += $(call cc-option, $(CFLAGS),-fno-unit-at-a-time,)
>
> And if so, we can do this change.  What we pass as 2nd argument
> shouldn't matter for this test.
>
> call cc-option is complicated to get right, sorry :(

If it doesn't matter, better not to pass anything, rather than confuse
the reader into thinking it does matter. This seems to work:
translate.o: QEMU_CFLAGS += $(call cc-option, , -fno-unit-at-a-time,)

But strangely, this doesn't:
translate.o: QEMU_CFLAGS += $(call cc-option, "", -fno-unit-at-a-time,)

However, what if the second argument did matter? I don't understand
the problem with the original syntax.

Debugging makefiles sucks.

-Hollis