[Python-Dev] PY_FORMAT_SIZE_T warnings on OS X (original) (raw)

Tim Peters tim.peters at gmail.com
Sun Apr 2 01:59:16 CEST 2006

[Brett Cannon]

I think these are all Tim's fault =) :

No, they're Anthony's fault :-) He added this clause to pyport.h yesterday:

if SIZEOF_SIZE_T == SIZEOF_INT

define PY_FORMAT_SIZE_T ""

and that's obviously triggering on your platform. He added this (at my suggestion) to shut up similar gcc warnings on some other box. Before he added it, PY_FORMAT_SIZE_T was "l" on that box (and on yours) If it had remained "l", you wouldn't be getting warnings now, but he still would.

On his box, the gripes where about passing a size_t argument to a "%lu" format, but size_t resolved to unsigned int, not to unsigned long. sizeof(int) == sizeof(long) on that box (and on yours), so the warning isn't really helpful.

Objects/object.c: In function 'PyNegativeRefcount': Objects/object.c:144: warning: format '%d' expects type 'int', but argument 7 has type 'Pyssizet'

And I bet (you should check) that Py_ssize_t resolves to "long" on your box, and that sizeof(long) == sizeof(int) on your box, so that again the warning is just a damned nuisance.

... [similar complaints] ...

What's odd about them is that that the use of PYFORMATSIZET seems to be correct, so I don't know what the problem is.

My best guess is above. gcc appears to be generating type complaints based on "name equivalence" rather than "structure equivalence" here (meaning it's comparing integer types by the names they resolve to rather than to the combination of size and signedness regardless of name). Worming around that would probably require a bunch of poke-and-hope experimenting with various gcc's, of which I have none :-)

Unfortunately gcc -E Include/pyport.h is no help since PYFORMATSIZET is not showing up defined (possibly because gcc says it can't find pyconfig.h).

You can run on it this part in isolation:

#ifndef PY_FORMAT_SIZE_T

if SIZEOF_SIZE_T == SIZEOF_INT

define PY_FORMAT_SIZE_T ""

elif SIZEOF_SIZE_T == SIZEOF_LONG

define PY_FORMAT_SIZE_T "l"

elif defined(MS_WINDOWS)

define PY_FORMAT_SIZE_T "I"

else

error "This platform's pyconfig.h needs to define PY_FORMAT_SIZE_T"

endif

#endif

after sticking on the right expansions for the SIZEOF_xyz thingies -- but it's clear enough from the error messages that the SIZEOF_INT branch is triggering (it's complaining about format '%d', not format '%ld' or format '%Id').

More information about the Python-Dev mailing list