lang: ast: add diag for do keyword in inline for-loop

lang/diag.c

@@ -8,12 +8,20 @@
 
 static const struct ivy_diag_class diag_classes[] = {
 	ERROR_CLASS(IVY_LANG_E_UNRECOGNISED_SYMBOL, "Unrecognised symbol"),
+	ERROR_CLASS(
+		IVY_LANG_E_INCORRECT_INLINE_FOR_LOOP,
+		"Incorrect inline for-loop"),
 };
 static const size_t nr_diag_classes = sizeof diag_classes / sizeof diag_classes[0];
 
 static const struct ivy_diag_msg diag_msg[] = {
 	MSG(IVY_LANG_MSG_UNKNOWN_SYMBOL_ENCOUNTERED,
             "encountered a symbol that is not part of the Ivy syntax."),
+	MSG(IVY_LANG_MSG_DO_UNEXPECTED_IN_INLINE_FOR,
+            "`[yellow]do[reset]` is not used in inline for-loops."),
+	MSG(IVY_LANG_MSG_PREVIOUS_EXPRESSION_IS_FOR_BODY,
+            "the previous expression is used as the for-loop body. perhaps you "
+            "forgot a [blue]statement separator[reset]?"),
 };
 static const size_t nr_diag_msg = sizeof diag_msg / sizeof diag_msg[0];