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

M.-A. Lemburg mal at egenix.com
Mon Jun 28 17:31:40 CEST 2010


M.-A. Lemburg 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.
> 
> Also note that in some cases you may actually want to have
> a debug build with optimizations turned on, e.g. to track down
> a compiler optimization bug.
> 
>>> and how do you know
>>> whether the compiler accepts -g as option ?
>>
>> 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. ?
> 
> AC_PROG_CC checks whether the compiler supports -g and always
> uses it in that case. The option is supported by more compilers
> than just GCC. E.g. IBM's xlC and Intel's icl compilers support
> that option as well.

Sorry, Intel's compiler is called "icc", not "icl":

http://software.intel.com/sites/products/documentation/hpc/compilerpro/en-us/cpp/mac/man/icc.txt

IBM's compiler:

http://publib.boulder.ibm.com/infocenter/macxhelp/v6v81/index.jsp?topic=/com.ibm.vacpp6m.doc/compiler/ref/ruoptlst.htm

-- 
Marc-Andre Lemburg
eGenix.com

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