Workaround for https://github.com/rust-lang/rust/issues/74935 to reduce the boilerplate of manual match statements.

weights.rs

// `?` is still unstable in const contexts :(
macro_rules! option_try {
	($($opt:tt)+) => {
		match $($opt)+ {
			Some(t) => t,
			None => return None,
		}
	};
}

impl Weight {
	/// Checked [`Weight`] addition. Computes `self + rhs`, returning `None` if overflow occurred.
	pub const fn checked_add(&self, rhs: &Self) -> Option<Self> {
		Some(Self {
			ref_time: option_try!(self.ref_time.checked_add(rhs.ref_time)),
			proof_size: option_try!(self.proof_size.checked_add(rhs.proof_size)),
		})
	}
}