[Python-Dev] Proper usage of size_t (original) (raw)

Loewis Martin von Martin.vonLoewis at hpi.uni-potsdam.de
Wed Sep 3 19:40:24 EDT 2003


On Win64, the Windows SDK compiler gives tons of warnings that type conversions may involve truncation. For example, in 2.3 stringobject.c, a subset of the warnings is

..\Objects\stringobject.c(285) : warning C4267: '=' : conversion from 'size_t' to 'int', possible loss of data ..\Objects\stringobject.c(316) : warning C4244: 'function' : conversion from '__int64' to 'int', possible loss of data ..\Objects\stringobject.c(554) : warning C4244: 'function' : conversion from '__int64' to 'int', possible loss of data ..\Objects\stringobject.c(812) : warning C4267: 'function' : conversion from 'size_t' to 'int', possible loss of data ..\Objects\stringobject.c(2154) : warning C4244: 'function' : conversion from '__int64' to 'int', possible loss of data ..\Objects\stringobject.c(3410) : warning C4267: 'return' : conversion from 'size_t' to 'int', possible loss of data ..\Objects\stringobject.c(3618) : warning C4267: 'return' : conversion from 'size_t' to 'int', possible loss of data ..\Objects\stringobject.c(3737) : warning C4244: '=' : conversion from '__int64' to 'int', possible loss of data ..\Objects\stringobject.c(4072) : warning C4244: '=' : conversion from '__int64' to 'int', possible loss of data ..\Objects\stringobject.c(4076) : warning C4244: '=' : conversion from '__int64' to 'int', possible loss of data

These warnings occur for stuff like

i = strlen(p);

where i is of type int, but strlen returns size_t, and that might exceed what int can store. Likewise, in

_PyString_Resize(&string, s - PyString_AS_STRING(string));

the pointer difference is of type size_t, but PyString_Resize expects int.

I'd be willing to go through and replace "int" by "size_t" whereever I find it appropriate, for Python 2.4. I would keep the current object layout for the moment, but change function signatures, which would cause ABI breakage on platforms where sizeof(size_t)!=sizeof(int).

What do you think?

Regards, Martin



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