--- a/src/ai/api/ai_error.cpp	Thu Apr 03 22:18:52 2008 +0000
+++ b/src/ai/api/ai_error.cpp	Thu Apr 03 22:32:28 2008 +0000
@@ -8,7 +8,7 @@
 AIError::AIErrorMap AIError::error_map = AIError::AIErrorMap();
 AIError::AIErrorMapString AIError::error_map_string = AIError::AIErrorMapString();
 
-/* static */ uint AIError::GetLastError()
+/* static */ AIErrorType AIError::GetLastError()
 {
 	return AIObject::GetLastError();
 }
@@ -18,19 +18,19 @@
 	return (*error_map_string.find(AIError::GetLastError())).second;
 }
 
-/* static */ uint AIError::StringToError(uint internal_string_id)
+/* static */ AIErrorType AIError::StringToError(StringID internal_string_id)
 {
 	AIErrorMap::iterator it = error_map.find(internal_string_id);
 	if (it == error_map.end()) return ERR_UNKNOWN;
 	return (*it).second;
 }
 
-/* static */ void AIError::RegisterErrorMap(uint internal_string_id, uint ai_error_msg)
+/* static */ void AIError::RegisterErrorMap(StringID internal_string_id, AIErrorType ai_error_msg)
 {
 	error_map[internal_string_id] = ai_error_msg;
 }
 
-/* static */ void AIError::RegisterErrorMapString(uint ai_error_msg, const char *message)
+/* static */ void AIError::RegisterErrorMapString(AIErrorType ai_error_msg, const char *message)
 {
 	error_map_string[ai_error_msg] = message;
 }

--- a/src/ai/api/ai_error.hpp	Thu Apr 03 22:18:52 2008 +0000
+++ b/src/ai/api/ai_error.hpp	Thu Apr 03 22:32:28 2008 +0000
@@ -71,7 +71,7 @@
 	 * Get the last error.
 	 * @return An ErrorMessages enum value.
 	 */
-	static uint GetLastError();
+	static AIErrorType GetLastError();
 
 	/**
 	 * Get the last error in string format (for human readability).
@@ -85,7 +85,7 @@
 	 * @param internal_string_id The string to convert.
 	 * @return The NoAI equivalent error message.
 	 */
-	static uint StringToError(uint internal_string_id);
+	static AIErrorType StringToError(StringID internal_string_id);
 
 	/**
 	 * Map an internal OpenTTD error message to it's NoAI equivalent.
@@ -93,7 +93,7 @@
 	 * @param internal_string_id The OpenTTD StringID used for an error.
 	 * @param ai_error_msg The NoAI equivalent error message.
 	 */
-	static void RegisterErrorMap(uint internal_string_id, uint ai_error_msg);
+	static void RegisterErrorMap(StringID internal_string_id, AIErrorType ai_error_msg);
 
 	/**
 	 * Map an internal OpenTTD error message to it's NoAI equivalent.
@@ -101,11 +101,11 @@
 	 * @param ai_error_msg The NoAI error message representation.
 	 * @param message The string representation of this error message, used for debug purposes.
 	 */
-	static void RegisterErrorMapString(uint ai_error_msg, const char *message);
+	static void RegisterErrorMapString(AIErrorType ai_error_msg, const char *message);
 
 private:
-	typedef std::map<uint, uint> AIErrorMap;
-	typedef std::map<uint, const char *> AIErrorMapString;
+	typedef std::map<StringID, AIErrorType> AIErrorMap;
+	typedef std::map<AIErrorType, const char *> AIErrorMapString;
 
 	static AIErrorMap error_map;
 	static AIErrorMapString error_map_string;

--- a/src/ai/api/ai_object.cpp	Thu Apr 03 22:18:52 2008 +0000
+++ b/src/ai/api/ai_object.cpp	Thu Apr 03 22:32:28 2008 +0000
@@ -56,12 +56,12 @@
 	return GetDoCommandStruct(_current_player)->costs.GetCost();
 }
 
-void AIObject::SetLastError(uint last_error)
+void AIObject::SetLastError(AIErrorType last_error)
 {
 	GetDoCommandStruct(_current_player)->last_error = last_error;
 }
 
-uint AIObject::GetLastError()
+AIErrorType AIObject::GetLastError()
 {
 	return GetDoCommandStruct(_current_player)->last_error;
 }
@@ -153,7 +153,7 @@
 	res = ::DoCommand(tile, p1, p2, flags, procc);
 	/* The command failed, so return */
 	if (::CmdFailed(res)) {
-		AIObject::SetLastError(AIError::StringToError(_error_message));
+		SetLastError(AIError::StringToError(_error_message));
 		return false;
 	}
 
@@ -199,7 +199,7 @@
 	}
 
 	if (::CmdFailed(res)) {
-		AIObject::SetLastError(AIError::StringToError(_error_message));
+		SetLastError(AIError::StringToError(_error_message));
 		return false;
 	}
 

--- a/src/ai/api/ai_object.hpp	Thu Apr 03 22:18:52 2008 +0000
+++ b/src/ai/api/ai_object.hpp	Thu Apr 03 22:32:28 2008 +0000
@@ -23,6 +23,11 @@
 #endif
 
 /**
+ * The type (an alias) for all errors the AI API knows.
+ */
+typedef uint AIErrorType;
+
+/**
  * The callback function for Mode-classes.
  */
 typedef bool (AIModeProc)(TileIndex tile, uint32 p1, uint32 p2, uint procc, CommandCost costs);
@@ -78,12 +83,12 @@
 	 * Set the DoCommand last error.
 	 * @note last_error is an ERR_* from a ErrorMessages enum.
 	 */
-	static void SetLastError(uint last_error);
+	static void SetLastError(AIErrorType last_error);
 
 	/**
 	 * Get the DoCommand last error.
 	 */
-	static uint GetLastError();
+	static AIErrorType GetLastError();
 
 	/**
 	 * Set the current mode of your AI to this proc.