Visual Studio interaction with CMake presets

[jcar87]

• user's project already has a CMakePresets.json that specifies / defines the dependency provider as a cmake cache variable
• Conan generates a CMakePresets that causes Visual Studio IDE to use that instead

cc: @Ahajha

[Ahajha]

Specifically, I am using CMakePresets for the dependency provider preset. For reference, I have this:

{
  "version": 3,
  "configurePresets": [
    {
      "architecture": {
        "value": "x64",
        "strategy": "external"
      },
      "binaryDir": "${sourceDir}/out/build/${presetName}",
      "cacheVariables": {
        "CMAKE_PROJECT_TOP_LEVEL_INCLUDES": "~/Documents/cmake-conan/conan_provider.cmake",
        "CMAKE_BUILD_TYPE": "Debug",
        "CMAKE_INSTALL_PREFIX": "${sourceDir}/out/install/${presetName}"
      },
      "description": "Sets Ninja generator, compilers, x64 architecture, build and install directory, debug build type",
      "displayName": "CMake + Conan: Debug",
      "generator": "Ninja",
      "name": "windows-default",
      "vendor": {
        "microsoft.com/VisualStudioSettings/CMake/1.0": {
          "hostOS": [ "Windows" ]
        }
      }
    }
  ]
}

(I have the path to cmake-conan hardcoded to a known global location, adjust as needed)

What happens is:

1. Configure CMake with the given preset
2. CMake calls Conan
3. Conan generates or writes to CMakeUserPresets.json
4. Visual Studio detects the 'change', so it reconfigures CMake, restarting the loop

Workaround is to disable generating the presets file on a per-conanfile basis, but would be nice to be able to disable generation globally.