build fails with clang, python3 and numpy 1.7.1 and higher

[selasley]

The build succeeds if I change
void initObjToJSON(void)
to
int initObjToJSON(void)
in objToJSON.c, but I don't know if there are repercussions. I haven't tested with numpy 1.7 and lower.

---

$ git log
commit 51cc9d9
...
$ python3 -c "import numpy;print(numpy.version)"
1.7.1
(also fails with 1.8.0.dev-f7ea474)
$ python3 setup.py build
...
pandas/src/ujson/python/objToJSON.c:118:5: error: void function 'initObjToJSON' should not return a value [-Wreturn-type]
import_array();
^~~~~~~~~~~~~~
/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/site-packages/numpy/core/include/numpy/__multiarray_api.h:1693:144: note: expanded from macro 'import_array'
#define import_array() {if (_import_array() < 0) {PyErr_Print(); PyErr_SetString(PyExc_ImportError, "numpy.core.multiarray failed to import"); return NUMPY_IMPORT_ARRAY_RETVAL; } }

---

from generate_numpy_api.py

if PY_VERSION_HEX >= 0x03000000

define NUMPY_IMPORT_ARRAY_RETVAL NULL

else

define NUMPY_IMPORT_ARRAY_RETVAL

endif

define import_array() {if (_import_array() < 0) {PyErr_Print(); PyErr_SetString(PyExc_ImportError, "numpy.core.multiarray failed to import"); return NUMPY_IMPORT_ARRAY_RETVAL; } }

[cpcloud]

make ur change, run the full test suite, push to travis submit a PR and then it'll probably get merged if that passes. the first error is the one that matters here the numpy stuff is unrelated. returning a value from a void function is undefined and thus the compiler rightly fails

[cpcloud]

although i don't get this bug...clang can sometimes be very strict with it's warnings/errors...

[cpcloud]

oh i c. this is what happens when c macros look like functions....the pp is rewriting a return statement in there and clang is pickier than gcc...

[cpcloud]

@selasley can u try my fix? i don't have an reasonable way to use clang i would have to recompile python plus all of the deps that require cython so that's a bit prohibitive...

[selasley]

Sorry, I was away from the computer for a while. It builds with your change with python3, but I get an error trying to build with clang and python 2.7

pandas/src/ujson/python/objToJSON.c:118:5: error: non-void function 'initObjToJSON' should return a value [-Wreturn-type]
import_array();
^
/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/include/numpy/__multiarray_api.h:1678:144: note: expanded from macro 'import_array'
#define import_array() {if (_import_array() < 0) {PyErr_Print(); PyErr_SetString(PyExc_ImportError, "numpy.core.multiarray failed to import"); return NUMPY_IMPORT_ARRAY_RETVAL; } }

---

I think the problem arises from this section of generate_numpy_api.py

#if PY_VERSION_HEX >= 0x03000000
#define NUMPY_IMPORT_ARRAY_RETVAL NULL
#else
#define NUMPY_IMPORT_ARRAY_RETVAL
#endif

#define import_array() {if (_import_array() < 0) {PyErr_Print(); PyErr_SetString(PyExc_ImportError, "numpy.core.multiarray failed to import"); return NUMPY_IMPORT_ARRAY_RETVAL; } }

So under python 3 import_array() returns NULL and under python 2 it returns no value. Maybe the change should be

#if (PY_VERSION_HEX < 0x03000000)
void initObjToJSON(void)
#else
int initObjToJSON(void)
#endif
{
PyObject *mod_frame;
PyDateTime_IMPORT;

I was able to build pandas with clang and python 2.7 and 3.3.2 on my mac running OS X 10.8 with this change. This is my first time forking pandas and trying to use Travis following the CONTRIBUTING docs. I think it built OK - https://travis-ci.org/selasley/pandas/builds/8039302

[cpcloud]

return type should probably be some kind of pointer maybe void * since it's returning NULL...i'm not sure ... maybe whoever wrote this can comment or fix it i'm not sure who taht is though...

[cpcloud]

i pushed that fix, we'll see what happens

[selasley]

good catch. clang did issue a warning
warning: incompatible pointer to integer conversion returning 'void *' from a function with result type 'int'
but I missed it. pandas builds with clang and python 3 when initObjToJSON returns a void *
Thanks for your help.

[cpcloud]

i'll leave as int since NULL will be cast to 0 anyway.

[wesm]

merge the PR and close this one? OK with me if Kieran is OK with the PR

[jreback]

apparently 2.7 on clang is giving the same issue

maybe this is a compiler issue (rather than a version issue)?

anyone on mac can test?

https://groups.google.com/forum/?fromgroups=#!topic/pydata/8oq0ErM8_eE

[jreback]

cc @rhstanton