Visual Studio C static lib function exposing problem-CodePudding

I have created example of using static libraries. The goal is this functionality:

DllTestFunctDll.dll links static_lib.lib (contains fnStaticLibrary())
example.exe links DllTestFunctDll.dll (contains dllTestFunct())
main() calls directly fnStaticLibrary() and dllTestFunct().
dllTestFunct() calls directly fnStaticLibrary().

I don't understand one thing, this works only if fnStaticLibrary() is inside same project as main() and dllTestFunct().

If I create another solution that

DllTestFunctDll.dll links also static_lib.lib (contains fnStaticLibTest())
main() newly also calls directly fnStaticLibTest().
dllTestFunct() newly also calls directly fnStaticLibTest().

dllTestFunct() is able to call fnStaticLibTest() and main() is unable to call fnStaticLibTest() due to linker. But I am able to call fnStaticLibTest() inside dllTestFunct().

I used dumpbin to see what functions are exported:

dumpbin /EXPORTS "C:\\path\\DllTestFunctDll.dll"

Output:

ordinal hint RVA      name
      1    0 00001000 ?dllTestFunct@@YAXXZ = ?dllTestFunct@@YAXXZ (void __cdecl DllTestFunct(void))
      2    1 00001070 ?fnStaticLibrary@@YAXXZ = ?fnStaticLibrary@@YAXXZ (void __cdecl fnStaticLibrary(void))

You can see that fnStaticLibTest() is missing inside the output.

In both static lib projects I export function by "__declspec(dllexport) ".

I assume that the problem is inside the Visual Studio. Do you know how to solve it?

Thank you in advance for your answers.

CODE (VS17 solution) LINK:

CodePudding user response：

An object module is added from a .lib, if it is required. If the dll does not call (or reference) any item in a compilation unit (c/cpp file), it won't be added to the dll