Lifetimes: Updates to incorporate NLL

[vorner]

• Updated the explanations around lifetimes a bit.
• Made sure the examples that should fail still fail in edition 2018.
• Prefer rust,compile_fail instead of rust,ignore ‒ the latter
  allows the user to click on button and see the actual compile errors.
  Also, this'll tell us if something stops failing.

[RalfJung]

Prefer rust,compile_fail instead of rust,ignore ‒ the latter
allows the user to click on button and see the actual compile errors.
Also, this'll tell us if something stops failing.

You mean "the former"?

[vorner]

You mean "the former"?

Hmm, yes. I'll rewrite that on the before-merge rebase.

[Gankra]

note I intend to review this soon but I want to touch base with the lang team to understand NLL better before going over this in detail

[vorner]

Hello. Any progress here?

[vorner]

Hello

@gankro Is there a realistic chance you'd get around to it, or should we try to seek some other way of validating it that doesn't block on you? It's sitting here without progress for 5 months and the book contains outdated information that is no longer true :-(.

Maybe asking someone from the NLL implementers to skim the text for blatant factual lies and and you having a look if the text fits nicely with the rest of the book and is understandable would work?

[Gankra]

Yeah reviewing this has been my white whale. A true disaster I have created and inflicted upon you. :/

Part of the issue is that this substantial of a change requires actual, like, editing for effective communication, which I find very uncomfortable to do? I would definitely appreciate technical feedback from domain experts here, but this also needs the attention of like, a Writing Professional.

[Gankra]

r=me with minor nits

[vorner]

I've applied the suggestions into a new fixup. If it looks good, I'll squash the fixups to have nicer history.

I'm afraid this is based on old version of master that no longer compiles all the snippets (in other chapters). I don't want to mess the review with a full rebase yet, though, so I'm postponing the rebase to current master for when the changes here are ACKed. Is that OK?

[Gankra]

Thanks for not squashing! A couple more nits.

Feel free to squash + rebase everything this time, assuming there's not anything surprising.

[Gankra]

ready to land?

[vorner]

Yes :-).