Deprecating a function or a macro is equivalent to redefining it, as demonstrated in the previous recipe, and printing a message with DEPRECATION:

macro(somemacro)
  message(DEPRECATION "somemacro is deprecated")
  _somemacro(${ARGV})
endmacro()

Deprecating a variable can be achieved by first defining the following:

function(deprecate_variable _variable _access)
  if(_access STREQUAL "READ_ACCESS")
    message(DEPRECATION "variable ${_variable} is deprecated")
  endif()
endfunction()

This function is then attached to the variable that is about to be deprecated:

variable_watch(somevariable deprecate_variable)

If in this case ${included_modules} is read (READ_ACCESS), then the deprecate_variable function issues the message with DEPRECATION.