[Python-Dev] what environment variable should contain compiler warning suppression flags? (original) (raw)

Mark Dickinson dickinsm at gmail.com
Mon Jun 28 17:44:00 CEST 2010

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 ACPROGCC 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.

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 ACPROGCC 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.

Mark

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