XXX used as a TODO Label

[mpguerra]

It was observed that several annotations in the codebase contain the string XXX and appear to represent a TODO or future task. These items may not be identified or documented via code searches for open issues. Examples include:

zebra/zebra-network/src/policies.rs

Lines 6 to 12 in 6f896ef

	/// A very basic retry policy with a limited number of retry attempts.
	///
	/// XXX Remove this when <https://github.com/tower-rs/tower/pull/414> lands.
	#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
	pub struct RetryLimit {
	remaining_tries: usize,
	}

zebra/zebra-network/src/constants.rs

Lines 13 to 14 in a4cb835

	// XXX should these constants be split into protocol also?
	use crate::protocol::external::types::*;

zebra/zebra-network/src/peer/connection.rs

Lines 136 to 139 in a4c5f75

	fn process_message(&mut self, msg: Message) -> Option<Message> {
	let mut ignored_msg = None;
	// XXX can this be avoided?
	let tmp_state = std::mem::replace(self, Handler::Finished(Ok(Response::Nil)));

The above examples are not exhaustive. It is recommended to review the codebase for the XXX tag (or any other similar tag) and align them with a consistent approach to task tracking.