error[E0277]: the size for values of type `Self` cannot be known at compilation time
  --> $DIR/trait-with-supertraits-needing-sized-self.rs:3:22
   |
LL | trait ArithmeticOps: Add<Output=Self> + Sub<Output=Self> + Mul<Output=Self> + Div<Output=Self> {}
   |                      ^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
   |
note: required by a bound in `Add`
  --> $SRC_DIR/core/src/ops/arith.rs:LL:COL
   |
LL | pub trait Add<Rhs = Self> {
   |               ^^^^^^^^^^ required by this bound in `Add`
help: consider further restricting `Self`
   |
LL | trait ArithmeticOps: Add<Output=Self> + Sub<Output=Self> + Mul<Output=Self> + Div<Output=Self> + Sized {}
   |                                                                                                +++++++

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.