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

Brett Cannon brett at python.org
Sun Apr 2 02:40:56 CEST 2006

On 4/1/06, Tim Peters <tim.peters at gmail.com> wrote:

[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 SIZEOFSIZET == SIZEOFINT # define PYFORMATSIZET "" 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, PYFORMATSIZET was "l" on that box (and on yours) If it had remained "l", you wouldn't be getting warnings now, but he still would.

Great, so either Anthony gets warnings or I do.

On his box, the gripes where about passing a sizet argument to a "%lu" format, but sizet 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.

Well that figures.

> 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 Pyssizet 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 :-)

This is just so ridiculous. Is there even a way to do this reasonably? Would we have to detect when Py_ssize_t resolves to either int or long and when the size of both is the same force to the same name on all platforms?

> 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 PYFORMATSIZET # if SIZEOFSIZET == SIZEOFINT # define PYFORMATSIZET "" # elif SIZEOFSIZET == SIZEOFLONG # define PYFORMATSIZET "l" # elif defined(MSWINDOWS) # define PYFORMATSIZET "I" # else # error "This platform's pyconfig.h needs to define PYFORMATSIZET" # endif #endif after sticking on the right expansions for the SIZEOFxyz thingies -- but it's clear enough from the error messages that the SIZEOFINT branch is triggering (it's complaining about format '%d', not format '%ld' or format '%Id').

OK, so how should we solve this one? Or should we just ignore it and hope gcc eventually wises up and starting using structural equivalence for its printf checks? =)

-Brett

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