[Python-Dev] what environment variable should contain compiler warning suppression flags?

[M.-A. Lemburg]

Mark Dickinson wrote:
> On Mon, Jun 28, 2010 at 4:28 PM, M.-A. Lemburg <mal at egenix.com> wrote:
>> Mark Dickinson wrote:
>>> On Mon, Jun 28, 2010 at 3:04 PM, M.-A. Lemburg <mal at egenix.com> wrote:
>>>> Why do you think that the default -O2 is unwanted
>>>
>>> Because it can cause debug builds of Python to be built with
>>> optimization enabled, as we've already seen at least twice.
>>
>> Then let me put it this way:
>>
>> How many Python users will compile Python in debug mode ?
>>
>> The point is that the default build of Python should use
>> the correct production settings for the C compiler out of
>> the box and that's what AC_PROG_CC is all about.
>>
>> I'm pretty sure that Python developers who want to use a
>> debug build have enough code foo to get the -O2 turned into a -O0
>> either by adjust OPT and/or by providing their own CFLAGS env var.
> 
> Shrug.  Clearly someone at some point in the past thought it was a
> good idea to have --with-pydebug builds use -O0.  If there's going to
> be a deliberate decision to drop that now, then that's fine with me.

Ah right, the time machine again :-)

OPT already uses -O0 if --with-pydebug is used and the
compiler supports -g. Since OPT gets added after CFLAGS, the override
already happens...

>>> I don't.  It could easily be tested for, though.  Alternatively,
>>> setting an empty CFLAGS to '-g' could be done just for gcc, since this
>>> is the only compiler for which AC_PROG_CC adds -O2.
>>
>> ... and then end up with default Python builds which don't have
>> debug symbols available to track down core dumps, etc. ?
> 
> No, I don't see how that follows.  I was suggesting that *for gcc
> only*, an empty CFLAGS be set to '-g' before calling AC_PROG_CC.  The
> *only* effect this would have would be that for gcc, if the user
> hasn't specified CFLAGS, then CFLAGS ends up being '-g' rather than
> '-g -O2' after the AC_PROG_CC call. But I'm really not looking for an
> argument here;  I just wanted to understand why you thought AC_PROG_CC
> setting CFLAGS was important, and you've explained that.  Thanks.

Sorry, that was a misunderstand on my part.

-- 
Marc-Andre Lemburg
eGenix.com

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