Re: [Mingw-cross-env-list] Undefined Reference errors when linking

[Mark Brand]

Simon A. Eugster wrote:
> On 02/20/2012 10:25 AM, Mark Brand wrote:
> > > My project now successfully compiles, linking fails however, with
> > > approximately 42 billion error messages like the ones posted at the 
> > > end.
> > <snip>
> > > CMakeFiles/PhenoCam.dir/objects.a(exporterMainwindow.cpp.obj):exporterMainwindow.cpp:(.text+0xb1b): 
> > >
> > > undefined reference to `__imp___ZN5QJson6ParserC1Ev'
> > > CMakeFiles/PhenoCam.dir/objects.a(exporterMainwindow.cpp.obj):exporterMainwindow.cpp:(.text+0xb40): 
> > >
> > > undefined reference to `__imp___ZN5QJson6Parser5parseERK10QByteArrayPb'
> > > CMakeFiles/PhenoCam.dir/objects.a(exporterMainwindow.cpp.obj):exporterMainwindow.cpp:(.text+0x1379): 
> > >
> > > undefined reference to `__imp___ZN5QJson6ParserD1Ev'
> > > CMakeFiles/PhenoCam.dir/objects.a(exporterMainwindow.cpp.obj):exporterMainwindow.cpp:(.text+0x1735): 
> > >
> > > undefined reference to `__imp___ZN5QJson6ParserD1Ev'
> > > CMakeFiles/PhenoCam.dir/objects.a(selectVideoStep.cpp.obj):selectVideoStep.cpp:(.text+0x9e8): 
> > >
> > > undefined reference to `__imp___ZN5QJson6ParserC1Ev'
> > > CMakeFiles/PhenoCam.dir/objects.a(selectVideoStep.cpp.obj):selectVideoStep.cpp:(.text+0xa16): 
> > >
> > > undefined reference to `__imp___ZN5QJson6Parser5parseEP9QIODevicePb'
> > > CMakeFiles/PhenoCam.dir/objects.a(selectVideoStep.cpp.obj):selectVideoStep.cpp:(.text+0xc7c): 
> > >
> > > undefined reference to `__imp___ZN5QJson6ParserD1Ev'
> >
> > Hi Simon,
> >
> > You might find some clues here:
> >
> > http://stackoverflow.com/questions/5159353/how-can-i-get-rid-of-the-imp-prefix-in-the-linker-in-vc 
> >
> >
> >
> > Somebody who knows more about cmake and qjson might be able to give more
> > specific advice.
> >
> > Mark
>
> Thanks for the link! If I understand correctly the json .lib is 
> generated for a .dll? 

No, the problem is with the object files you are building. They wrongly 
have the "import" prefix on the symbol names.

> Which is controlled by cross-env? Or what could I do? Is it a mistake 
> in my CMake files?

The prefixing in qjson_export.h is sensitive to QJSON_STATIC. You should 
probably have a look to see how it works.

The solution is probably to define QJSON_STATIC in your application.

Mark