Re: [Swig-user] Call signature difference between SWIG 1.3 and 2.0

[William S F. <ws...@fu...>]

On 19/09/11 14:55, Teemu Ikonen wrote:
> Hello all,
>
> I'm trying to compile a Python SWIG interface to to Coin3D
> (coin3d.org) called pivy (see
> http://hg.sim.no/Pivy/default/file/8eab90908f2a/interfaces for the
> interface code). The interface generation used to work perfectly with
> the swig 1.3 series, but with swig 2.0.4 compilation of the generated
> wrapper code fails.
>
> It turns out that the problem appears when a call to a function with a
> function pointer reference argument is made. The function causing the
> problem has this signature:
>
>      static SbBool getHeaderData(const SbString&  headerstring,
>                                SbBool&  isbinary,
>                                float&  ivversion,
>                                SoDBHeaderCB *&  precallback,
>                                SoDBHeaderCB *&  postcallback,
>                                void *&  userdata,
>                                SbBool substringok = FALSE);
>
> where SoDBHeaderCB is
>
>      typedef void SoDBHeaderCB(void * data, SoInput * input);
>
> Version 1.3 produces this call in the generated Python extension code:
>
> result = (SbBool)SoDB::getHeaderData((SbString const
> &)*arg1,*arg2,*arg3,*arg4,*arg5,*arg6,arg7);
>
> and version 2.0.4:
>
> result = (SbBool)SoDB::getHeaderData((SbString const
> &)*arg1,*arg2,*arg3,arg4,arg5,*arg6,arg7);
>
> i.e. args 4 and 5 are not dereferenced, although rest of the argument
> unpacking code in the Python extension is identical between the two
> swig versions. When compiling, a matching getHeaderData function is
> not found, causing this error with swig 2.0.4:
>
> pivy/coin_wrap.cpp: In function 'PyObject*
> _wrap_SoDB_getHeaderData__SWIG_0(PyObject*, PyObject*)':
> pivy/coin_wrap.cpp:35402:96: error: no matching function for call to
> 'SoDB::getHeaderData(const SbString&, SbBool&, float&, void
> (**&)(void*, SoInput*), void (**&)(void*, SoInput*), void*&, SbBool&)'
> pivy/coin_wrap.cpp:35402:96: note: candidate is:
> /usr/include/Inventor/SoDB.h:65:17: note: static SbBool
> SoDB::getHeaderData(const SbString&, SbBool&, float&, void (*&)(void*,
> SoInput*), void (*&)(void*, SoInput*), void*&, SbBool)
> /usr/include/Inventor/SoDB.h:65:17: note:   no known conversion for
> argument 4 from 'void (**)(void*, SoInput*)' to 'void (*&)(void*,
> SoInput*)'
>
> See here http://people.debian.org/~lucas/logs/2011/08/22/pivy_0.5.0~svn765-2_lsid64.buildlog
> for a full Debian build log.
>
> There are no typemaps affecting function pointers in the interface
> code that I can find, so this looks to me like a genuine regression in
> swig. Any hints on how to get this interface working?
>

It is now fixed for swig-2.0.5, see
http://swig.svn.sourceforge.net/swig/?rev=12814&view=rev

Until it is released, you could use %exception as a workaround to 
replace the call to the wrapped function.

William