Before: ```c++ #define INITGUID #include <unknwn.h> const GUID& a() { return __uuidof(IUnknown); } const GUID& b() { return IID_IUnknown; } ``` ``` $ clang -xc++ -target i386-pc-windows-gnu -nostdinc -I include -I include/msvcrt a.cpp -masm=intel -nostdlib a.cpp:3:26: warning: instantiation of variable '__wine_uuidof<IUnknown>::uuid' required here, but no definition is available [-Wundefined-var-template] [...] 1 warning generated. /usr/bin/ld: /tmp/a-7e5d2f.o:a.cpp:(.rdata$.refptr._IID_IUnknown+0x0): undefined reference to `IID_IUnknown' /usr/bin/ld: /tmp/a-7e5d2f.o:a.cpp:(.rdata$.refptr.__ZN13__wine_uuidofI8IUnknownE4uuidE+0x0): undefined reference to `__wine_uuidof<IUnknown>::uuid' clang: error: linker command failed with exit code 1 (use -v to see invocation) ``` After: Creates an a.exe with no warnings. (With a() as entry point; figuring out how to give it a real entry point is offtopic to this MR.)