Re: [Swig-user] Anonymous unions

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

Rush Manbert wrote:
> I am trying to use SWIG to wrap some C/C++ code for access from Java. I'm using version 1.3.40.
> 
> I am getting warnings of the form:
> Warning(312): Nested union not currently supported (ignored).
> 
> because of code like this:
> 
> typedef struct
> {
>     int a;
>     union
>     {
>         int u1;
>         bool u2;
>     }
> { MyStruct_T;
> 
> (Of course, the real thing is much more complicated than this.)
> 
> I assume that if I did something like this:
> 
> typedef union
> {
>     int u1;
>     bool u2;
> } MyUnion_T;
> 
> typedef struct
> {
>     int a;
>     MyUnion_T u;
> } MyStruct_T;
> 
> then SWIG could handle it, but from what I have read, it looks like the anonymous union case is not handled.
> 
> I'm hoping that I have either missed something, or that there is some other workaround for wrapping an anonymous union like this.

Nested structs/unions etc is a weak point in SWIG, although it got 
somewhat better in 2.0.0, so you could try upgrading. If your code is 
c++ and presumably also passing the -c++ option to SWIG, the nested 
class/union support is limited. However, even if your code is C code, 
anonymous structs/unions are not currently supported. No one so far has 
put in the effort to support them. Workaround is to not use a named union.

See http://www.swig.org/Doc2.0/SWIG.html#SWIG_nested_structs for C 
nested struct support and for the fairly recently updated C++ support: 
http://www.swig.org/Doc2.0/SWIGPlus.html#SWIGPlus_nested_classes .

William