Schema message types should be extendable by subclasses.

This is a rather primitive way of doing it, but it works and isn't a huge and complicated change.

src/serialization/schema_validator.cpp

@@ -367,12 +367,6 @@ void schema_validator::print(message_info& el)
 	case MISSING_KEY:
 		missing_key_error(el.file, el.line, el.tag, el.key, create_exceptions_);
 		break;
-	case WRONG_TYPE:
-		wrong_type_error(el.file, el.line, el.tag, el.key, el.value, create_exceptions_);
-		break;
-	case WRONG_PATH:
-		wrong_path_error(el.file, el.line, el.tag, el.key, el.value, create_exceptions_);
-		break;
 	}
 }
 
@@ -548,4 +542,16 @@ bool schema_self_validator::reference::can_find(const wml_tag& root, const confi
 	return root.find_tag(value_, root, cfg) != nullptr;
 }
 
+void schema_self_validator::print(message_info& el)
+{
+	switch(el.type) {
+	case WRONG_TYPE:
+		wrong_type_error(el.file, el.line, el.tag, el.key, el.value, create_exceptions_);
+		break;
+	case WRONG_PATH:
+		wrong_path_error(el.file, el.line, el.tag, el.key, el.value, create_exceptions_);
+		break;
+	}
+}
+
 } // namespace schema_validation{

src/serialization/schema_validator.hpp

@@ -77,9 +77,8 @@ class schema_validator : public abstract_validator
 	typedef std::stack<cnt_map> cnt_stack;
 
 protected:
-	enum message_type{ WRONG_TAG, EXTRA_TAG, MISSING_TAG, EXTRA_KEY, MISSING_KEY, WRONG_VALUE, WRONG_TYPE, WRONG_PATH };
-private:
-	// error_cache
+	using message_type = int;
+	enum { WRONG_TAG, EXTRA_TAG, MISSING_TAG, EXTRA_KEY, MISSING_KEY, WRONG_VALUE, NEXT_ERROR };
 
 	/**
 	 * Messages are cached.
@@ -112,20 +111,21 @@ class schema_validator : public abstract_validator
 		}
 	};
 
+	/** Controls the way to print errors. */
+	bool create_exceptions_;
+private:
+
 	typedef std::deque<message_info> message_list;
 	typedef std::map<const config*, message_list> message_map;
 
-	void print(message_info&);
+	virtual void print(message_info&);
 
 	/** Reads config from input. */
 	bool read_config_file(const std::string& filename);
 
 	/** Shows, if validator is initialized with schema file. */
 	bool config_read_;
 
-	/** Controls the way to print errors. */
-	bool create_exceptions_;
-
 	/** Root of schema information. */
 	wml_tag root_;
 
@@ -182,6 +182,8 @@ class schema_self_validator : public schema_validator
 	std::multimap<std::string, std::string> derivations_;
 	int type_nesting_, condition_nesting_;
 	bool tag_path_exists(const config& cfg, const reference& ref);
+	void print(message_info& message) override;
+	enum { WRONG_TYPE = NEXT_ERROR, WRONG_PATH, NEXT_ERROR };
 };
 
 } // namespace schema_validation{