[Python-Dev] autoconf question: howto add to CFLAGS and LDFLAGS?

[Thomas Wouters]

On Wed, Aug 16, 2000 at 04:55:42PM -0700, Trent Mick wrote:

> I am currently trying to port Python to Monterey (64-bit AIX) and I need
> to add a couple of Monterey specific options to CFLAGS and LDFLAGS (or to
> whatever appropriate variables for all 'cc' and 'ld' invocations) but it
> is not obvious *at all* how to do that in configure.in. Can anybody helpme
> on that?

You'll have to write a shell 'case' for AIX Monterey, checking to make sure
it is monterey, and setting LDFLAGS accordingly. If you look around in
configure.in, you'll see a few other 'special cases', all to tune the
way the compiler is called. Depending on what you need to do to detect
monterey, you could fit it in one of those. Just search for 'Linux' or
'bsdos' to find a couple of those cases.

> ANother issue that I am having. This is how the python executable is linked
> on Linux with gcc:

> gcc  -Xlinker -export-dynamic python.o ../libpython2.0.a -lpthread -ldl  -lutil -lm  -o python

> It, of course, works fine, but shouldn't the proper (read "portable")
> invocation to include the python2.0 library be

> gcc  -Xlinker -export-dynamic python.o -L.. -lpython2.0 -lpthread -ldl  -lutil -lm  -o python

> That invocation form (i.e. with the '-L.. -lpython2.0') works on Linux, and
> is *required* on Monterey. Does this problem not show up with other Unix
> compilers. My hunch is that simply listing library (*.a) arguments on the gcc
> command line is a GNU gcc/ld shortcut to the more portable usage of -L and
> -l. Any opinions. I would either like to change the form to the latter or
> I'll have to special case the invocation for Monterey. ANy opinions on which
> is worse.

Well, as far as I know, '-L.. -lpython2.0' does something *different* than
just '../libpython2.0.a' ! When supplying the static library on the command
line, the library is always statically linked. When using -L/-l, it is
usually dynamically linked, unless a dynamic library doesn't exist. We
currently don't have a libpython2.0.so, but a patch to add it is on Barry's
plate. Also, I'm not entirely sure about the search order in such a case:
gcc's docs seem to suggest that the systemwide library directories are
searched before the -L directories. I'm not sure on that, though.

Also, listing the library on the command line is not a gcc shortcut, but
other people already said that :) I'd be suprised if AIX removed it (but not
especially so; my girlfriend works with AIX machines a lot, and she already
showed me some suprising things ;) but perhaps there is another workaround ?

-- 
Thomas Wouters <thomas@xs4all.net>

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