[Cython] Cython generates invalid C code for some generator expressions in cdef functions

[Stefan Behnel]

Michael Enßlin schrieb am 08.05.2015 um 14:37:
> Take the following example:
> 
> 
> $ cat t2.pyx
> cdef void read_callback():
>     foo = b"asdf"
>     bar = (c for c in foo)
> 
> 
> 
> $ cython t2.pyx
> 
> 
> 
> $ gcc -I/usr/include/python3.4m t2.c
> t2.c: In function ‘__pyx_f_2t2_read_callback’:
> t2.c:778:12: error: ‘None’ undeclared (first use in this function)
>      return None;
>             ^
> t2.c:778:12: note: each undeclared identifier is reported only once for
> each function it appears in
> t2.c:778:5: warning: ‘return’ with a value, in function returning void
>      return None;
>      ^
> 
> 
> Note that the error does not occur for
> 
> bar = (c for c in b"asdf")
> 
> or
> 
> bar = [c for c in b"asdf"]

Thanks for the report. This should fix it:

https://github.com/cython/cython/commit/f8b952c16dc569e50642d426e328d2d0fe0f53aa

Stefan