Fused types problems with class inheritance

[Javier Baez]

Hi,

I am using cython 0.17 on Ubuntu 12.04 x64. I had found a problem when I use fused types and class inheritance

This is my example code:

from libcpp.string cimport string

from libc.stdint cimport uint64_t

ctypedef fused attribute_key_fused_type:

    string

    long

cdef class EntityBase:

    cdef:

        string _key

    def __init__(self, key):

        if isinstance(key, str):

            self.setKey(<string>key)

        elif type(key) is long:

            self.setKey(<long>key)

    cdef void setKey(self, attribute_key_fused_type key):

        if attribute_key_fused_type is string:

            self._key = key

        elif attribute_key_fused_type is long:

            pass

If you use only this code runs ok, but if you create a inherited class as for example:

cdef class Entity(EntityBase):

    pass

Now I have problems with C++ code generated:

test.cpp:421:78: error: declaration of ‘void (* __pyx_vtabstruct_4test_EntityBase::__pyx_fuse_0setKey)(__pyx_obj_4test_EntityBase*, std::string)’

test.cpp:419:78: error: conflicts with previous declaration ‘void (* __pyx_vtabstruct_4test_EntityBase::__pyx_fuse_0setKey)(__pyx_obj_4test_EntityBase*, std::string)’

test.cpp:422:71: error: declaration of ‘void (* __pyx_vtabstruct_4test_EntityBase::__pyx_fuse_1setKey)(__pyx_obj_4test_EntityBase*, long int)’

test.cpp:420:71: error: conflicts with previous declaration ‘void (* __pyx_vtabstruct_4test_EntityBase::__pyx_fuse_1setKey)(__pyx_obj_4test_EntityBase*, long int)’

Going to test.cpp file I have this:

/* "test.pyx":42

 *     long

 * 

 * cdef class EntityBase:             # <<<<<<<<<<<<<<

 *     cdef:

 *         string _key

 */

struct __pyx_vtabstruct_4test_EntityBase {

  void (*__pyx_fuse_0setKey)(struct __pyx_obj_4test_EntityBase *, std::string);

  void (*__pyx_fuse_1setKey)(struct __pyx_obj_4test_EntityBase *, long);

  void (*__pyx_fuse_0setKey)(struct __pyx_obj_4test_EntityBase *, std::string);

  void (*__pyx_fuse_1setKey)(struct __pyx_obj_4test_EntityBase *, long);

};

The prototype functions for string and long is duplicated in the same class then g++ can not compile the source code

if anyone can solve this problem I would greatly appreciate

Best Regards

Javier

[Marc-Alexandre Côté]

I have the same problem. Have you found a solution?

[Marc-Alexandre Côté]

I am using Cython 0.20.2 on LinuxMint 17 x64.

I created a basic example to reproduce the error:

https://gist.github.com/MarcCote/8ea8bb5d31bea8d5da66

Does someone encounter this problem before?

[Javier Baez]

Hi Marc,

I never fix the error because currently, I am not using Cython in my project.

Best regards

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[Stefan Behnel]

> I am using Cython 0.20.2 on LinuxMint 17 x64.
>
> I created a basic example to reproduce the error:
> https://gist.github.com/MarcCote/8ea8bb5d31bea8d5da66

This is now

http://trac.cython.org/cython_trac/ticket/833

Sorry it took so long to have anyone respond. Let's try to get this fixed
for 0.21.1.

Stefan

[Marc-Alexandre Côté]

Great, thanks

Marc

[Marc-Alexandre Côté]

Any development on this issue? I can confirm it is still there in Cython
0.23dev.

Marc

On 14-09-10 12:08 AM, Stefan Behnel wrote:

[Stefan Behnel]

> Any development on this issue? I can confirm it is still there in Cython
> 0.23dev.

No-one is working on it AFAICT.

Stefan

[arjangi...@gmail.com]

Hi,

I ran into this bug as well and believe I traced back the problem. In Symtab.py, CClassScope.declare_inherited_c_attributes() forces the base class to be fully specialized early on in the parsing pipeline (i.e., fused types are specialized to all possible types). Later on, FusedCFuncDefNode.copy_cdef() visits the base class again and attempts a time to specialize the methods containing fused types. So this is why we end up with duplicate entries in the vtable of the base class.

I managed to compile the example by adding a check for duplicate entries when FusedCFuncDefNode.copy_cdef() specializes the fused types (i.e., simply removing the earlier entry from env.cfunc_entries when there is a cname collision). However, this is just a minimal workaround and not a real fix, plus that I still hit a redeclaration problem when adding a third level of inheritance.

Would there be a way to get some attention to this bug from more seasoned cython contributors?

Cheers,

Arjan

[Julien Jerphanion]

Just for future readers' information: I've been able to compile both reproducers with Cython 0.29.23.