feat(cmakev2/project): add warning for usage of deprecated variables

The COMPONENTS and EXCLUDE_COMPONENTS variables are unused in cmakev2. A
deprecation warning will be printed if they are set. This change also
includes a helper functions for printing deprecation warnings.

Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>

tools/cmakev2/project.cmake

@@ -568,6 +568,10 @@ macro(idf_project_init)
         # Ensure this function is executed only once throughout the entire
         # project.
 
+        # Warn about the use of deprecated variables.
+        deprecate_variable(COMPONENTS)
+        deprecate_variable(EXCLUDE_COMPONENTS)
+
         # Set PROJECT_NAME build property
         __init_project_name()
 

tools/cmakev2/utilities.cmake

@@ -109,6 +109,40 @@ function(idf_dbg)
     message(DEBUG " IDF: ${joined}")
 endfunction()
 
+#[[
+    idf_deprecated(<msg>...)
+
+    *msg[in]*
+
+        Message to print.
+
+    Print deprecated ``<msg>``. Multiple messages are concatenated into a
+    single message with no separator between them.
+#]]
+function(idf_deprecated)
+    set(joined "")
+    math(EXPR last "${ARGC} - 1")
+    foreach(i RANGE 0 ${last})
+        string(APPEND joined "${ARGV${i}}")
+    endforeach()
+    message(DEPRECATION " IDF: ${joined}")
+endfunction()
+
+#[[
+    deprecate_variable(<var>)
+
+    *var[in]*
+
+        Deprecated variable name.
+
+    Print a warning about the use of a deprecated variable.
+#]]
+function(deprecate_variable var)
+    if(${var})
+        idf_deprecated("The use of the '${var}' variable is deprecated and will be ignored.")
+    endif()
+endfunction()
+
 #[[
     __get_real_target(TARGET <target>
                       OUTPUT <variable>)