[Qemu-devel] Re: [COMMIT 8a2e6ab] Remove CFLAGS parameter in cc-option

[Thomas Monjalon]

Anthony Liguori wrote:
> Juan Quintela wrote:
> > malc <address@hidden> wrote:
> >> On Thu, 10 Sep 2009, Juan Quintela wrote:
> >>> malc <address@hidden> wrote:
> >>>> On Wed, 9 Sep 2009, Anthony Liguori wrote:
> >>>>> From: Juan Quintela <address@hidden>
> >>>>>
> >>>>> With cc-option we are testing if gcc just accept a particular option,
> >>>>> we don't need CFLAGS at all.  And this fixes the recursive problem
> >>>>> with CFLAGS
> >>>>
> >>>> This is nonsense, previous options, those in CFLAGS, might conflict
> >>>> with the new ones.
> >>>
> >>> The only thing that we are testing is if gcc support that _option_
> >>>
> >>> What is the use case tat you have in mind?  A first grep on gcc man
> >>> page don't show options that conflict with each other.
> >>
> >> If you want artificial exmaples i can come up with plenty, and from the
> >> top of my head -m486 with -msse2 are quite incompatible with each other,
> >> furthermore, point is this - testing one option in isolation is broken.
> >
> > Ok. For the case that we were using, it don't matter at all.  But in
> > general, there "could" (it is only one cc-option call in all sources).
> >
> > Anthony, what do you preffer:
> > - revert the patch and add another one that changes += by :=
>
> No, I don't want to revert this patch and switch to :=.  += should
> work.  I don't understand why it doesn't.
>
> What I'd prefer is for someone to figure out the root cause of += not
> working for us.  If we can't, I'd like a big fat comment stating that
> it's a known deficiency and we'll move on.

"make" complains about an infinite recursive assignment because the first 
assignment of CFLAGS defines a recursively-expanded variable and the right 
value is a macro which uses the CFLAGS.

As explained in 
http://www.gnu.org/software/make/manual/html_node/Appending.html , it can be 
fixed by making CFLAGS a simply-expanded variable at its first assignment.

I have submitted a patch.
-- 
Thomas