-- The typechecker (not the renamer) checks that all
-- the declarations are for the right class
let
- at_doc = text "In the associated types in an instance declaration"
+ at_doc = text "In the associated types of an instance declaration"
at_names = map (head . tyClDeclNames . unLoc) ats
in
checkDupNames at_doc at_names `thenM_`