Incorrect error message for def with void* argument

[robertwb]

Reported by nikratio on 18 Sep 2015 19:11 UTC Consider the following code:

from libc cimport stdio

def do_test():
    cdef int i
    cdef int vals[   callbacks = [](3]

)
    for i in range(3):
        vals[= i
        def cb(void* i_=vals+i):
            stdio.printf('%d\n', *<int*>i_)
        callbacks.append(cb)

    for cb in callbacks:
        cb()

This cannot work, because Cython has to make cb callable from Python - but there is no good way to convert a Python object to void*.

However, Cython's error message is a bit misleading:

$ cython -3 -Wextra --force -3 --directive embedsignature=True     mylib.pyx --fast-fail

Error compiling Cython file:
------------------------------------------------------------
...
    cdef int vals[3](i])

    callbacks = [   for i in range(3):
        vals[i](]
) = i
        def cb(void* i_=vals+i):
       ^
------------------------------------------------------------

mylib.pyx:10:8: Cannot convert 'void *' to Python object

Should this say Cannot convert Python object to 'void*' (i.e., the other way around)?

Migrated-From: http://trac.cython.org/ticket/867