Macro forward_ref_generic::forward_ref_binop

macro_rules! forward_ref_binop {
    (
        $( [ $($generic:tt)* ] )?
        impl Add for $lhs:ty $(, $rhs:ty )?
        $( where $($bound:tt)* )?
    ) => { ... };
    (
        $( [ $($generic:tt)* ] )?
        impl Sub for $lhs:ty $(, $rhs:ty )?
        $( where $($bound:tt)* )?
    ) => { ... };
    (
        $( [ $($generic:tt)* ] )?
        impl Mul for $lhs:ty $(, $rhs:ty )?
        $( where $($bound:tt)* )?
    ) => { ... };
    (
        $( [ $($generic:tt)* ] )?
        impl Div for $lhs:ty $(, $rhs:ty )?
        $( where $($bound:tt)* )?
    ) => { ... };
    (
        $( [ $($generic:tt)* ] )?
        impl $impl:ident, $meth:ident for $lhs:ty
        $( where $($bound:tt)* )?
    ) => { ... };
    (
        $( [ $($generic:tt)* ] )?
        impl $impl:ident, $meth:ident for $lhs:ty, $rhs:ty
        $( where $($bound:tt)* )?
    ) => { ... };
}

For types T: Copy, U: Copy for which binary operator binop is implemented (T binop U), also implement T binop &U, &T binop U and &T binop &U.

For readability, the expected syntax of the macro is the following:

( [ Generics ] )?
impl Trait, Method for LHS(, RHS)?
( where Bounds )?

• Generics are comma-seperated type or const generics
• Trait is the trait to be implemented
• Method is the method that Trait defines
  (can be ommitted for Add, Sub, Mul and Div)
• LHS is the type of the left hand side of the operation (i.e. T)
• RHS is the type of the right hand side of the operation (i.e. U)
  if no RHS is given, LHS = RHS is assumed
• Bounds are comma-seperated trait bounds for the listed generics