Allow URLs to be used as the keys of a TreeMap.

[cgaebel]

This is needed to get bucketed profiling working in servo.

[SimonSapin]

I don’t think Ord makes sense on URLs. Would it work to use url.to_string() as a key, instead?

[cgaebel]

Why wouldn't Ord make sense? And I can use url.to_string(), but it'd be less efficient...

[SimonSapin]

How should you decide if an URL is "greater" or "lesser" than another? The implementation given by deriving is completely arbitrary.

[cgaebel]

Oh. I thought it'd be lexicographic.

[SimonSapin]

It probably is lexicographic, but based on an internal representation that might change and does not say anything meaningful about the URLs.

[cgaebel]

Ok. Makes sense to me. Take another look?

[SimonSapin]

Although marginally better, I’d still rather not have Url implement Ord at all.

But more importantly, using TreeMap<Url, ...> with an implementation of Ord that is based on Url::serialize will serialize a lot more often than using TreeMap<String, ...> with string keys from Url::serialize. I suggest doing the latter.

[cgaebel]

Ah. That's a great idea! I'll close this.