+ head_type_synonym_msg = parens (
+ text "All instance types must be of the form (T t1 ... tn)" $$
+ text "where T is not a synonym." $$
+ text "Use -XTypeSynonymInstances if you want to disable this.")
+
+ head_type_args_tyvars_msg = parens (
+ text "All instance types must be of the form (T a1 ... an)" $$
+ text "where a1 ... an are distinct type *variables*" $$
+ text "Use -XFlexibleInstances if you want to disable this.")