Processes/coding-guidelines.md

@@ -29,7 +29,7 @@ Dead code is bad; it suffers from code rot, and it looks unclean. There are some
 Any dead code (both files that are unused and blocks of commented-out code) should in principle be removed. If there is a very good reason to keep it around for a while, it must be accompanied by a comment explaining why it is still there, and when it will be removed or enabled again. This comment should point to a ticket so that we do not forget about it.
 
 # Python Style  
-We don't use python code anymore. If you found any leftovers, feel free to remove them.
+We don't use python code anymore in the core code. If you found any leftovers, feel free to remove them.
 
 # C++ Style 
 
@@ -571,6 +571,10 @@ Names of tests should be similar to classes and method names for that language.
 
 # Makefile.am Guidelines 
 
+## Make portability
+
+Makefiles must never depend on a particular make, for instance the `$(<function> ...)` construct of GNU make for shell, foreach, wildcard, etc, are forbidden.
+
 ## Subdirectories 
 
 If there is are one or more subdirectories, the first line in the file