MSVC programs calling an MinGW DLL - c++

Question

Following this short tutorial, I get stuck at the stage of linking the DLL built by MinGW. Here are the two simple source code files I use for practice purpose.
foo.cpp for foo.dll
const char *greeting(void)
{
return "Hello, World!";
}
main.cpp for main.exe
#include <cstdio>
const char * greeting(void);
int main(int argc, char *argv[])
{
std::printf("%s\n", greeting());
return 0;
}
I ran all the commands in MSYS2 on Windows 10. Below is the commands and their outputs. It looks time-wasting long, but really only the last 2 lines matter.
### Generate foo.def and foo.dll.
$ g++ foo.cpp -shared -Wall -Wl,--output-def=foo.def -o foo.dll
$ cat foo.def
EXPORTS
_Z8greetingv #1
### Generate foo.lib and foo.exp.
$ lib /machine:x64 /def:foo.def
Microsoft (R) Library Manager Version 14.27.29112.0
Copyright (C) Microsoft Corporation. All rights reserved.
Creating library foo.lib and object foo.exp
### Try to generate .exe file.
$ cl main.cpp foo.lib
Microsoft (R) C/C++ Optimizing Compiler Version 19.27.29112 for x64
Copyright (C) Microsoft Corporation. All rights reserved.
main.cpp
Microsoft (R) Incremental Linker Version 14.27.29112.0
Copyright (C) Microsoft Corporation. All rights reserved.
/out:main.exe
"/LIBPATH:C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\lib\x64"
"/LIBPATH:C:\Program Files (x86)\Windows Kits\10\Lib\10.0.19041.0\um\x64"
"/LIBPATH:C:\Program Files (x86)\Windows Kits\10\Lib\10.0.19041.0\ucrt\x64"
main.obj
foo.lib
main.obj : error LNK2019: unresolved external symbol "char const * __cdecl greeting(void)" (?greeting##YAPEBDXZ) referenced in function main
main.exe : fatal error LNK1120: 1 unresolved externals
As you can see, the last 2 lines is the problem. It will work, if change the calling convention with extern "C". So, apparently something went wrong with this mysterious calling convention stuff. I'm new to MSVC toolset by the way. So, maybe this is a stupid question. Any hint? Thanks.
EDIT: Please note that the codes above are supposed to be compiled as C++ codes instead of C codes. They look simple and, of course, there isn't any object-oriented code in them. They are just an experiment, but I'm planing to put C++ classes into .dll file if it's doable. Therefore, I'm wondering if it's still possible when name mangling is taken into account.