VS build environment is not set when using clang

[bobbrow]

So what is the trick to get VSCode to call vcvars? My preset:

{
    "name": "win-ninja-release",
    "displayName": "win-ninja-release",
    "description": "Ninja generator release",
    "generator": "Ninja",
    "binaryDir": "${sourceDir}/build/ninja/release",
    "inherits": ["ninja-general" , "win-vcpkg_settings" ],
    "cacheVariables": {
        "CMAKE_C_COMPILER" : "$penv{LLVMInstallDir}/bin/clang-cl.exe",
        "CMAKE_CXX_COMPILER" : "$penv{LLVMInstallDir}/bin/clang-cl.exe",
        "CMAKE_BUILD_TYPE": "Release",
    },
    "architecture": {
        "value": "x64",
        "strategy": "external"
     },
     "toolset": {
        "value": "host=x64",
        "strategy": "external"
     },
    "vendor": {
        "microsoft.com/VisualStudioSettings/CMake/1.0": {
          "hostOS": [ "Windows" ],
          "intelliSenseMode" : "windows-clang-x64",
          "enableMicrosoftCodeAnalysis" : true
        }
    }
},

Originally posted by @Neumann-A in https://github.com/microsoft/vscode-cmake-tools/issues/1885#issuecomment-991155721

[bobbrow]

(Copied from #1885)

We currently only auto-configure the vcvars env for you if your clang-cl corresponds to a Visual Studio Kit we've previously scanned.

[SupinePandora43]

My current workaround:

export CMAKE_C_COMPILER=clang
export CMAKE_CXX_COMPILER=clang++
cd build
cmake ..
cd ..

[Diyou]

Without calling vcvars I'm getting

[cmake] -- The C compiler identification is unknown
[cmake] -- The CXX compiler identification is unknown

And

CMake Error: CMake was unable to find a build program corresponding to "Ninja".  CMAKE_MAKE_PROGRAM is not set.

When ninja is not in path eventhough it's installed with visual studio.

Seems to be unrelated to clang ... the environment just does not get set. I need to launch vscode from a Visual Studio Developer Command Prompt (the x64 specifically because it defaults to x86 for some reason)

I'd like to keep the presets platform agnostic and free of absolute paths.

[aiyolo]

Does this issue have a solution now?