Exporting function under a namespace always lead to unresolve reference when linking

[grayfox]

In a shared lib, I have the following:

#ifndef SHAREDLIB_H
#define SHAREDLIB_H
#include "SharedLib_global.h"
 
namespace Fx{
    SHAREDLIBSHARED_EXPORT int FunctionUnderNamespace();
}
 
SHAREDLIBSHARED_EXPORT int FunctionOutsideNamespace();
#endif // SHAREDLIB_H

#ifndef SHAREDLIB_H
#define SHAREDLIB_H
#include "SharedLib_global.h"

namespace Fx{
    SHAREDLIBSHARED_EXPORT int FunctionUnderNamespace();
}

SHAREDLIBSHARED_EXPORT int FunctionOutsideNamespace();
#endif // SHAREDLIB_H

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This will compile without problem, but in the app source file:

#include <SharedLib.h>
#include <QDebug>
int main()
{
    //int v  = Fx::FunctionUnderNamespace(); // link error
    int v = FunctionOutsideNamespace(); // works fine
    qDebug() << v;
    return 0;
}

#include <SharedLib.h>
#include <QDebug>
int main()
{
    //int v  = Fx::FunctionUnderNamespace(); // link error
    int v = FunctionOutsideNamespace(); // works fine
    qDebug() << v;
    return 0;
}

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Calling the function under a namespace will not even be compiled.
Do I actually need to export the namespace?

[d_stranz]

Your SHAREDLIBSHARED_EXPORT macro is probably not including the namespace when it declares the function for export. The linker is looking for Fx::FunctionUnderNamespace() and your macro apparently is exporting the global function ::FunctionUnderNamespace() instead.

Try doing this instead:

SHAREDLIBSHARED_EXPORT int Fx::FunctionUnderNamespace();

SHAREDLIBSHARED_EXPORT int Fx::FunctionUnderNamespace();

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and get rid of the namespace Fx {} scope declaration that wraps the export declaration.

[grayfox]

Your SHAREDLIBSHARED_EXPORT macro is probably not including the namespace when it declares the function for export. The linker is looking for Fx::FunctionUnderNamespace() and your macro apparently is exporting the global function ::FunctionUnderNamespace() instead.

Try doing this instead:

SHAREDLIBSHARED_EXPORT int Fx::FunctionUnderNamespace();

SHAREDLIBSHARED_EXPORT int Fx::FunctionUnderNamespace();

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and get rid of the namespace Fx {} scope declaration that wraps the export declaration.

I tried your suggestion but the shared lib won't even compile.

[MarekR22]

link error means that there is no definition of problematic function!
The main question is how did you define this symbol in dll? (I assume that macro SHAREDLIBSHARED_EXPORT is properly handled).
As a safety check use this function in your dll using proper namespace.