mkSmallTupleSelector :: [Id]        -- The tuple args
          -> Id         -- The selected one
          -> Id         -- A variable of the same type as the scrutinee
          -> CoreExpr        -- Scrutinee
          -> CoreExpr
mkSmallTupleSelector [var] should_be_the_same_var _ scrut
  = ASSERT(var == should_be_the_same_var)
    scrut
mkSmallTupleSelector :: [Id]        -- The tuple args
          -> Id         -- The selected one
          -> Id         -- A variable of the same type as the scrutinee
          -> CoreExpr        -- Scrutinee
          -> CoreExpr
mkSmallTupleSelector [var] should_be_the_same_var _ scrut
  = ASSERT(var == should_be_the_same_var)
    scrut
mkSmallTupleSelector [var] should_be_the_same_var _ scrut
  = ASSERT(var == should_be_the_same_var)
    scrut