与其他库链接的静态库-LINKER警告

Question

I'm building SDL2 static library. To use it in my program, I have to link with (static) SDL2.lib, but also with winmm.lib, imm32.lib, version.lib, which I assume are stubs for some Windows DLLs. My main goal is to create such a version of static SDL2, so that my program won't have to be linked with those other 3 .libs. I would like to have all the symbols needed in the static library, so that I have to link the exe only with SDL2.lib. I'm using MS VS2012. I had the idea to use the Librarian when building the static SDL2.lib so I added those other 3 libs to Librarian/Additional Dependencies. That worked like a charm. My exe has to be linked only against SDL2.lib.

But when the .lib was linked, I got warnings:

warning LNK4221: This object file does not define any previously undefined public symbols, so it will not be used by any link operation that consumes this library  imm32.lib(IMM32.dll)    SDL2main
warning LNK4221: This object file does not define any previously undefined public symbols, so it will not be used by any link operation that consumes this library  version.lib(VERSION.dll)    SDL2main

Now my idea is this: imm32.lib and version.lib do not define any previously undefined (in SDL2.lib) symbols. So they are not needed, because all of the symbols in SDL2.lib can be resolved. So I removed those 2 libs from the Librarian and recompiled SDL2.lib. Now when I'm linking my exe against it, I got some unresolved symbols (possibly from those 2 removed .libs).

Could somebody explain to me the meaning of those warnings? And how to avoid them?

Answer 1

It seems those symbols aren't used in SDL2.lib, but are used in your main. That's why you have to link those 3 files with your main, and not take a shortcut.