First draft of feature arguments and conforms to.

src/type_checker/tbon_tc_error.e

@@ -36,6 +36,7 @@ feature -- Access
 feature -- Error codes
 
 	err_code_ancestor_does_not_exist,
+	err_code_argument_type_does_not_exist,
 	err_code_class_already_in_cluster,
 	err_code_class_does_not_exist,
 	err_code_class_exists,

src/type_checker/tbon_tc_text_items.e

@@ -39,6 +39,17 @@ feature -- Error messages
 			Result.append_string (" does not exist.")
 		end
 
+	err_argument_type_does_not_exist(an_argument_name, a_feature_name, a_class_name: STRING): STRING
+		do
+			Result := "Type of argument "
+			Result.append_string (an_argument_name.string)
+			Result.append_string (" in feature ")
+			Result.append_string (a_feature_name.string)
+			Result.append_string (" in class ")
+			Result.append_string (a_class_name.string)
+			Result.append_string (" could not be found.")
+		end
+
 	err_class_already_in_cluster (a_name: STRING): STRING
 		do
 			Result := "Error defining cluster "

src/type_checker/textual_bon_type_checker.e

@@ -1066,6 +1066,43 @@ feature -- Type checking, static diagrams
 			end
 		end
 
+	check_feature_arguments(an_element: FEATURE_ARGUMENT_LIST; enclosing_feature: FEATURE_SPECIFICATION; enclosing_class: TBON_TC_CLASS_TYPE): BOOLEAN
+		note
+			rule: "[
+				In an environment where all arguments are OK,
+				and if the feature is redefined all arguments conform to its precursors,
+				`an_element' is OK.
+				]"
+		local
+			l_argument: FEATURE_ARGUMENT
+			l_string_list: STRING_LIST
+		do
+			Result := True
+			if enclosing_feature.has_arguments then
+				if first_phase then
+					from an_element.start until an_element.after loop
+						if an_element.item_for_iteration.identifiers.item_for_iteration.count > 1 then
+							from an_element.item_for_iteration.identifiers.start until an_element.item_for_iteration.identifiers.after loop
+								create l_string_list.make_list (an_element.item_for_iteration.identifiers.item_for_iteration)
+								create l_argument.make (l_string_list, an_element.item_for_iteration.type)
+								an_element.put_last (l_argument)
+							end
+							an_element.remove_at
+						else
+							an_element.forth
+						end
+					end
+					Result := an_element.for_all (agent (argument: FEATURE_ARGUMENT): BOOLEAN
+													do
+
+													end
+												)
+				elseif second_phase then
+
+				end
+			end
+		end
+
 	check_feature_clause (an_element: FEATURE_CLAUSE; enclosing_class: TBON_TC_CLASS_TYPE): BOOLEAN
 			-- Does `an_element' type check as a type FEATURE_CLAUSE?
 		note
@@ -1110,7 +1147,7 @@ feature -- Type checking, static diagrams
 				and the type of the feature is in the environment,
 				and all feature arguments are OK,
 				and if renamed is renamed consistently,
-				
+
 				]"
 		do
 			if  then

src/type_checker/types/tbon_tc_class_type.e

@@ -124,12 +124,26 @@ feature -- Status report
 	conforms_to (other: TBON_TC_TYPE): BOOLEAN
 			-- Does `Current' conform to `other'?
 		local
-			class_type: TBON_TC_CLASS_TYPE
+			l_ancestors: like Current.ancestors
 		do
-			class_type ?= other
-
-			if class_type /= Void then
-
+			if Current |=| other then
+				Result := True
+			elseif not attached {TBON_TC_CLUSTER_TYPE} other then
+				l_ancestors := Current.ancestors
+				Result := l_ancestors.exists (
+										agent (type: TBON_TC_CLASS_TYPE; l_other: TBON_TC_TYPE): BOOLEAN
+											do
+												Result := type |=| l_other
+											end (?, other)
+										)
+				if not Result then
+					Result := l_ancestors.for_all (
+											agent (type: TBON_TC_CLASS_TYPE; l_other: TBON_TC_TYPE): BOOLEAN
+												do
+													Result := type.conforms_to (l_other)
+												end (?, other)
+											)
+				end
 			else
 				Result := False
 			end