Integrate CMake subproject that requires executing a command

[LDAP]

What is the idiomatic way of integrating a CMake project as a subproject that requires executing a command to pull the dependencies?

The problem is cmake.subproject() fails if the dependencies are not available, however the command can only be executed after subproject() since that pulls the repository using the .wrap file.

This happens in many Google and Khronos projects, for example in shaderc and glslang which are the projects I would like to integrate.

[LDAP]

(I would be happy to provide a PR if necessary)

My current workaround is using a patch directory which overwrites the CMakeLists.txt.