VCPKG unable to use specified compiler within provided custom triplet/toolchain. Looking for any advice on possible user error.

[obscurelyme]

I have created a small repo that I have running fine when the triplets are either set to x64-windows or x64-mingw-dynamic, but if I wish to leverage llvm as my compiler I had set up a small toolchain file that I used as the VCPKG_CHAINLOAD_TOOLCHAIN_FILE and while vcpkg seems to understand it all, it then reverts back to using MSVC instead of Clang to build my libraries.

My understanding is that you can override the compiler detection through use of a custom triplet and toolchain and that's the point of attack I'm going for.

I have my repo here for folks to hopefully take a look and point out what I could be doing incorrectly here.

Commands I run...

cmake --preset=debug

cmake --build build

[Neumann-A]

Windows = cleaned up environment; so whatever you do you wont pass through your compiler
Windows = automatic vcvars setup if VCPKG_CHAINLOAD_TOOLCHAIN_FILE is not set in the triplet.

See here: https://github.com/Neumann-A/my-vcpkg-triplets/blob/master/x64-win-llvm.cmake
or more complicated here: #42129