Fix desugaring of record update (fixes Trac #2735)

[ghc-hetmet.git] / compiler / typecheck / TcExpr.lhs

diff --git a/compiler/typecheck/TcExpr.lhs b/compiler/typecheck/TcExpr.lhs
index 540292c..51d6f4b 100644 (file)
--- a/compiler/typecheck/TcExpr.lhs
+++ b/compiler/typecheck/TcExpr.lhs
@@ -1189,9 +1189,11 @@ tcRecordBinds data_con arg_tys (HsRecFields rbinds dd)
        do { rhs' <- tcPolyExprNC rhs field_ty
           ; let field_id = mkUserLocal (nameOccName field_lbl)
                                        (nameUnique field_lbl)
-                                       field_ty loc
-               -- The field_id has the *unique* of the selector Id
-               -- but is a LocalId with the appropriate type of the RHS
+                                       field_ty loc 
+               -- Yuk: the field_id has the *unique* of the selector Id
+               --          (so we can find it easily)
+               --      but is a LocalId with the appropriate type of the RHS
+               --          (so the desugarer knows the type of local binder to make)
           ; return (Just (fld { hsRecFieldId = L loc field_id, hsRecFieldArg = rhs' })) }
       | otherwise
       = do { addErrTc (badFieldCon data_con field_lbl)