mkCoreLet :: CoreBind -> CoreExpr -> CoreExpr
mkCoreLet (NonRec bndr rhs) body        -- See Note [CoreSyn let/app invariant]
  | needsCaseBinding (idType bndr) rhs
  = Case rhs bndr (exprType body) [(DEFAULT,[],body)]
mkCoreLet :: CoreBind -> CoreExpr -> CoreExpr
mkCoreLet (NonRec bndr rhs) body        -- See Note [CoreSyn let/app invariant]
  | needsCaseBinding (idType bndr) rhs
  = Case rhs bndr (exprType body) [(DEFAULT,[],body)]
mkCoreLet (NonRec bndr rhs) body        -- See Note [CoreSyn let/app invariant]
  | needsCaseBinding (idType bndr) rhs
  = Case rhs bndr (exprType body) [(DEFAULT,[],body)]