[vitaminCPP]

I fail to see why this would not work with gcc if it works with clang. The runtime?

[delta_p_delta_x]

'MinGW' is not GCC; it's an ABI, and from the developer perspective it is also the headers and the libraries. You can have GCC MinGW, Clang MinGW, Rust MinGW, Zig MinGW, C# AOT MinGW.

To answer your question, the headers.