This code demonstrates the linker error:
error LNK2005: "public: int __cdecl C::Called(void)" (?Called@C@@QEAAHXZ) already defined in obj1.obj
This is caused by a DLL exporting the same symbol that another .obj file contains due to an inline header definition.
See obj1.cpp and replace the call with the non-inline version to resolve the error.
clang-cl can avoid this problem with the the new /Zc:dllexportInlines- flag. (See
http://blog.llvm.org/2018/11/30-faster-windows-builds-with-clang-cl_14.html).
Open a Visual Studio x64 Developer Command prompt and run build.cmd to repro.