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

Mark Dickinson dickinsm at gmail.com
Sun Jun 27 21:43:34 CEST 2010

On Sun, Jun 27, 2010 at 12:37 AM, M.-A. Lemburg <mal at egenix.com> wrote:
> Brett Cannon wrote:
>> On Wed, Jun 23, 2010 at 14:53, Brett Cannon <brett at python.org> wrote:
>>> I finally realized why clang has not been silencing its warnings about
>>> unused return values: I have -Wno-unused-value set in CFLAGS which
>>> comes before OPT (which defines -Wall) as set in PY_CFLAGS in
>>> Makefile.pre.in.
>>> I could obviously set OPT in my environment, but that would override
>>> the default OPT settings Python uses. I could put it in EXTRA_CFLAGS,
>>> but the README says that's for stuff that tweak binary compatibility.
>>> So basically what I am asking is what environment variable should I
>>> use? If CFLAGS is correct then does anyone have any issues if I change
>>> the order of things for PY_CFLAGS in the Makefile so that CFLAGS comes
>>> after OPT?
>> Since no one objected I swapped the order in r82259. In case anyone
>> else uses clang to compile Python, this means that -Wno-unused-value
>> will now work to silence the warning about unused return values that
>> is caused by some macros. Probably using -Wno-empty-body is also good
>> to avoid all the warnings triggered by the UCS4 macros in cjkcodecs.
> I think you need to come up with a different solution and revert
> the change...

Agreed; this needs more thought.

For one thing, Brett's change has the result that --with-pydebug
builds end up being built with -O2 instead of -O0, which can make
debugging (e.g., with gdb) somewhat awkward.


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