Tracking issue for the Peekable::is_empty function

[alexcrichton]

This is a tracking issue for the peekable_is_empty feature which is the Peekable::is_empty function on iterators.

[oyvindln]

What is blocking this from being stabilised?

[sfackler]

Nothing in particular other than that we haven't gotten to it yet.

[alexcrichton]

🔔 This issue is now entering its cycle-long final comment period for deprecation 🔔

The libs team discussed this and concluded:

• The API is somewhat non-conventional by having an is_* query taking &mut self and mutate state.
• This is different from collections is_empty methods in the sense that the signature is different and there is no corresponding len
• It's the same as .peek().is_none() which is also very easy to call.

[alexcrichton]

The libs team discussed this at triage yesterday and the decision was to deprecate