Re: [xml] undefined reference to `_imp__xmlFree' error on mingw with msys for 2.6.5

[Igor Zlatkovic <igor zlatkovic com>]

Mikhail S Grushinskiy wrote:

> The problem fixes if I remove defined(IN_LIBXML) condition in xmlexports.h
> Not sure why it is needed, but without it everything compiles fine on mingw
> with msys.
>
> /* Windows platform with GNU compiler (Mingw) */
> #if defined(_WIN32) && defined(__MINGW32__)
>   #undef XMLPUBFUN
>   #undef XMLPUBVAR
>   #undef XMLCALL
> /*
>   #if defined(IN_LIBXML) && !defined(LIBXML_STATIC)
> */
>   #if !defined(LIBXML_STATIC)
>     #define XMLPUBFUN __declspec(dllexport)
>     #define XMLPUBVAR __declspec(dllexport) extern
>   #else
>     #define XMLPUBFUN
>     #if !defined(LIBXML_STATIC)
>       #define XMLPUBVAR __declspec(dllimport) extern
>     #else
>       #define XMLPUBVAR extern
>     #endif
>   #endif
>   #define XMLCALL __cdecl
>   #if !defined _REENTRANT
>     #define _REENTRANT
>   #endif
> #endif

That IN_LIBXML is used to determine wether libxml itself is being 
compiled, or some app which uses libxml. In the former case, symbols 
should be exported. In the latter, they should be imported.

The net effect of your doing is:

  #define XMLPUBFUN __declspec(dllexport)
  #define XMLPUBVAR __declspec(dllexport) extern
  #define XMLCALL __cdecl

The macro LIBXML_STATIC is never defined when using libtool. Only the 
makefiles in win32/ define this.

Now when an application using libxml2 (xmllint for example) includes 
libxml headers, it gets instructed to reexport libxml symbols. This 
results in few inconsistencies, but GCC seems to expect these and it 
handles them.

If I define the mongw block like this:

#if defined(_WIN32) && defined(__MINGW32__)
  #define XMLPUBFUN
  #ifdef __cplusplus
    #define XMLPUBVAR extern
  #else
    #define XMLPUBVAR
  #endif
  #if !defined _REENTRANT
    #define _REENTRANT
  #endif
#endif

I get best results without msys. Now everything links without a single 
frown. Can you please try that?

Ciao,
Igor