How to set a DEFER CALL for the directory added with add_subdirectory()

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1

Hello,

is there any option perhaps to set a DEFER CALL in the scope of the
directory that will be added with add_subdirectory()? Or if there is any other
way to “inject” some CMake module or code into the scope of the
add_subdirectory()?

Because, I’m adding a various number of project extensions with
add_subdirectory() and trying to do as little code repeating inside the
extension’s CMakeLists.txt:

function(foo_deferred_call)
  message(
    STATUS
    "This should be called in the extension scope: ${CMAKE_CURRENT_SOURCE_DIR}"
  )
  configure_file(config.h.in config.h)
endfunction()

foreach(extension ${extensions})
  cmake_language(DEFER DIRECTORY ${extension} CALL foo_deferred_call)
  add_subdirectory(${extension})
endforeach()

Issue is that for the DEFER CALL the directory must be known to CMake
otherwise the error pops up:

cmake_language DEFER DIRECTORY

    /path/to/ext/extension_name...

is not known. It may not have been processed yet.

Thank you for any possible hints or tips.