Re: [xml] MSYS and MINGW: undefined reference to _imp__xmlFree

[Roumen Petrov <bugtrack roumenpetrov info>]

Martin Schlemmer wrote:
> > > > On 11/8/2009 at 8:08 PM, Roumen Petrov <bugtrack roumenpetrov info> wrote:
> > Roumen Petrov wrote:
> > > Martin Schlemmer wrote:
> > > > Hi,
> > > [SNIP]
> > > It seems to me Martin is right but proposed patch is not correct to me. 
> > > I think that code has to set LIBXML_STATIC internally when is compiled 
> > > for static library. As libxml build is libtool based we may use PIC 
> > > definition. libtool when compile source for shared always set -DPIC .
>
> Idea was sort of to remove the need for that.  I will respond to Igor's mail about that.
>
> > Now with reverted commit
> > http://git.gnome.org/cgit/libxml2/commit/?id=a194ccb8d19ddde94c2c04ddf197e6a 
> > 629f7cc9b
> > , i.e. restored "...defined(IN_LIBXML)..." plus following patch
> > ==========================================
> > diff --git a/libxml.h b/libxml.h
> > index 3c44c83..1656ac2 100644
> > --- a/libxml.h
> > +++ b/libxml.h
> > @@ -90,4 +90,7 @@ void __xmlGlobalInitMutexDestroy(void);
> >   #endif
> >   #endif
> >   #endif
> > +#ifndef PIC
> > +#  define LIBXML_STATIC
> > +#endif
> >   #endif /* ! __XML_LIBXML_H__ */
> > ==========================================
>
> This probably will break MSVC and Borland.  Also non-libtool-enabled builds might also break,
> as "-fPIC -DPIC" is added by libtool, but ignored by gcc on win32 as all code on x86-win32 is already
> position independent.

No ! -fPIC is not set for gcc mingw target by libtool !

For mingw target it is another definition that you already use in the
patch proposed by you : #if defined(DLL_EXPORT) .... i.e. libtool for
mingw target set -DDLL_EXPORT -DPIC. For gcc on linux it is -fPIC -DPIC
. For other compilers as example -kPIC -DPIC.
In brief one is compiler flag and another is common for all platforms -
it is C preprocessor flag -DPIC.


> Not sure what to suggest with this, but to check that with reverted commit that xmlsec is indeed
> built with -DLIBXML_STATIC if linking to the static version of the library.

Don't mix preprocessor flags set by other projects when static linking
with libxml is required.


> Regards,
>
> Martin

Reference:
http://www.gnu.org/software/libtool/manual/html_node/Creating-object-files.html

Quote "...(you might have conditional code inside ‘#ifdef PIC’ for
example), ...". As in libxml exist another preprocessor directive
-DLIBXML_STATIC my suggestion is based on libtool documentation.
If modification to libxml.h is acceptable then Borland and MSVC
makefiles can set either -DPIC or -DLIBXML_STATIC. Both will work only
if first case build system will be more consistent.

Roumen