+
+bindIfaceTyVars_AT :: [IfaceTvBndr] -> ([TyVar] -> IfL a) -> IfL a
+-- Used for type variable in nested associated data/type declarations
+-- where some of the type variables are already in scope
+-- class C a where { data T a b }
+-- Here 'a' is in scope when we look at the 'data T'
+bindIfaceTyVars_AT [] thing_inside
+ = thing_inside []
+bindIfaceTyVars_AT (b@(tv_occ,_) : bs) thing_inside
+ = bindIfaceTyVars_AT bs $ \ bs' ->
+ do { mb_tv <- lookupIfaceTyVar tv_occ
+ ; case mb_tv of
+ Just b' -> thing_inside (b':bs')
+ Nothing -> bindIfaceTyVar b $ \ b' ->
+ thing_inside (b':bs') }
+\end{code}