Re: [Xen-devel] [PATCH] tools: work around collision of -O0 and -D_FORTIFY_SOURCE

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.02.15 at 12:08, <Ian.Jackson@xxxxxxxxxxxxx> wrote:
> Jan Beulich writes ("[PATCH] tools: work around collision of -O0 and 
> -D_FORTIFY_SOURCE"):
>> The former gets enforced by our debug builds, the latter appears to be
>> not uncommon for certain distros' Python packages. Newer glibc warns on
>> uses of _FORTIFY_SOURCE without optimization being enabled, which with
>> -Werror causes the build to fail.
> ...
>> --- a/tools/pygrub/Makefile
>> +++ b/tools/pygrub/Makefile
>> @@ -2,15 +2,24 @@
>>  XEN_ROOT = $(CURDIR)/../..
>>  include $(XEN_ROOT)/tools/Rules.mk
>>  
>> +py_cflags := $(shell $(PYTHON)-config --cflags)
>> +PY_CFLAGS = $(if $(strip $(py_cflags)),,\
>> +                 $(error '$(PYTHON)-config --cflags' produced no output))\
>> +            $(if $(filter -D_FORTIFY_SOURCE=%,\
>> +                          $(filter-out -D_FORTIFY_SOURCE=0,\
>> +                                       $(py_cflags))),\
>> +                 $(patsubst -O0,-O1,$(CFLAGS)),\
>> +                 $(CFLAGS)) $(APPEND_LDFLAGS)
> 
> There are lots of copies of this.  And it would IMO be better to do at
> least the probing in configure, resulting in something like this in
> configure:
> 
>  [ determine PY_XCFLAGS to be either '' or '-O0' ]
>  AC_SUBST(PY_XCFLAGS)
> 
> and
> 
>  PY_CFLAGS=@PY_CFLAGS@
> 
>     CC="$(CC)" CFLAGS="$(CFLAGS) $(PY_XCFLAGS)" $(PYTHON) setup.py build
> 
> (I assume that CFLAGS does override what comes out of setup.py.)

For one, PY_XCFLAGS='' wouldn't help, as we get -O0 from the
incoming CFLAGS. And then I'm not really intending to fiddle with
the configure scripts (albeit, having done the patch in the presented
form, I expected you to want it done that way) - this and alike is
what I specifically want to stay out of if at all possible. Since in any
event commit 1166ecf781 introduced a regression for multiple
people, perhaps if that is not supposed to be reverted Euan should
look into addressing that regression?

Jan


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