winXP 32-bit build problems

[reckoner]

trouble building latest tip on winxp 32:

  running build
  running build_py
  copying pandas\version.py -> build\lib.win32-2.6\pandas
  running build_ext
  skipping 'pandas\src\tseries.c' Cython extension (up-to-date)
  building 'pandas._tseries' extension
  C:\Program Files\Microsoft Visual Studio 9.0\VC\BIN\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Python26\lib\site-packages\numpy-1.6.1-py2.6-win32.egg\numpy\core\include -IC:\Python26\include -IC:\Python26\PC /Tcpandas\src\tseries.c /Fobuild\temp.win32-2.6\Release\pandas\src\tseries.obj
  tseries.c
  c:\documents and settings\reckoner\desktop\pandas\pandas\src\numpy_helper.h(29) : error C2036: 'void *' : unknown size
  pandas\src\tseries.c(25741) : warning C4244: 'function' : conversion from '__pyx_t_5numpy_int64_t' to 'Py_ssize_t', possible loss of data
  pandas\src\tseries.c(27030) : warning C4244: 'function' : conversion from '__pyx_t_5numpy_int64_t' to 'Py_ssize_t', possible loss of data
  pandas\src\tseries.c(29457) : warning C4244: 'function' : conversion from '__pyx_t_5numpy_int64_t' to 'Py_ssize_t', possible loss of data
  pandas\src\tseries.c(32203) : warning C4244: 'function' : conversion from '__pyx_t_5numpy_int64_t' to 'Py_ssize_t', possible loss of data

any help appreciated! I previously had no trouble building this. I have the latest cython and numpy releases.

Thanks!

[wesm]

@m-paradox do you know the answer here? the offending C code is

inline int
assign_value_1d(PyArrayObject* ap, Py_ssize_t _i, PyObject* v) {
  char *item;
  npy_intp i = (npy_intp) _i;
  item = PyArray_DATA(ap) + i * PyArray_STRIDE(ap, 0);
  return PyArray_DESCR(ap)->f->setitem(v, item, ap);
}

[wesm]

hi Sam I made the above changes. Can you verify that your build works and I'll close the issue?

[mwiebe]

PyArray_DATA(ap) returning void * is the problem, as it looks like you solved in your patch. There's also PyArray_BYTES which returns a char * instead of void *:

http://docs.scipy.org/doc/numpy/reference/c-api.array.html#PyArray_DATA

[wesm]

I got the MSVC compiler set up in my VM and verified that all's OK now. Tons of compiler warnings (Py_ssize_t -> int32_t casts) that I need to fix

[reckoner]

The fix works! Thanks!

@m-paradox: How did you find this? The compiler message complained about a void pointer in the numpy_helper.h file that did not have any 'void''s in it.

[mwiebe]

Wes found and fixed the issue, I was just showing that the original designers of the API had intended that PyArray_DATA be used when casting to a specific pointer (like double *), and PyArray_BYTES be used when processing generically (in this case). A 'void' doesn't have a size, so adding the stride-based offset to a 'void *' isn't defined.

I would prefer to change PyArray_DATA to also return char *, because the void * use case allows implicit conversion and is an easy source of errors.

[wesm]

Mark, I copy-pasted part of that method from multiarray/mappings.c in the NumPy codebase-- does that also need a cast to char * to work with MSVC?