[Python-Dev] Proper place to put extra args for building

[Brett C.]

Martin v. Löwis wrote:
> Brett C. wrote:
> 
>>Hmm.  OK, that is an interesting idea.  Would make rebuilding a lot easier if
>>it was just an environment variable that was part of the default OPT value;
>>``OPT="$BUILDFLAGS -g -Wall -Wstrict-prototyping".
>>
>>I say we go with that.  What is a good name, though?  PY_OPT?
> 
> 
> I think EXTRA_CFLAGS is common, and it would not specifically be part of
> OPT, but rather of CFLAGS.
> 

Works for me.  If no one objects I will check in the change for CFLAGS to make
it ``$(BASECFLAGS) $(OPT) "$EXTRA_CFLAGS"`` soon (is quoting it enough to make
sure that it isn't evaluated by configure but left as a string to be evaluated
by the shell when the Makefile is running?).

> 
>>I am only talking about that because that is how OPT is currently structured;
>>configure.in replaces the defaults with what the user provides if the
>>environment variable is set.  This is what I don't want.
> 
> 
> The question is whether the user is supposed to provide a value for OPT
> in the first place. "OPT" is a set of flag that (IMO) should control
> the optimization level of the compiler, which, in the wider sense, also
> includes the question whether debug information should be generated.
> It should be possible to link object files compiled with different
> OPT settings, so flags that will give binary-incompatible object files
> should not be in OPT.
> 

OK, that makes sense to me.

> It might be desirable to allow the user to override OPT, e.g. to specify
> that the compiler should not use -O3 but, say, -O1. I don't think there
> is much point in allowing OPT to be extended. But then, it is already
> possible to override OPT (when invoking make), which might be enough
> control.
> 

Probably.  I think as long as we state somewhere that EXTRA_CFLAGS is the place
to put binary-altering flags and to leave OPT for only binary-compatible flags
then that should be enough of a separation that most people probably won't
touch OPT most of the time since the defaults are good, but can if they want.

I assume this info should all be spelled out in the README and
Misc/Specialbuilds.txt .  Anywhere else?

-Brett