Clear explanation of the rules enforced by the alias checker needed

[nikomatsakis]

As far as I could tell, the precise rules enforced by the alias checker are not documented. I may well be wrong about this, but I searched the tutorial and reference manual for the word "alias" without success. This makes it hard to explain to people why a particular expression is or is not considered immutably rooted and so forth. We ought to have a chapter in the reference manual we can point to (perhaps even as part of the compiler error message). I guess @marijnh is by far the best qualified to write such a thing (both in the sense of being capable of a clear explanation and in the sense of being the one who understands that code the best). Perhaps we ought to wait until we decide what we are doing about regions, though. Anyway, if such a thing already exists, please close this bug and let me know where it is.

[marijnh]

It's not called 'alias' anymore, but safe reference. There's a bit about it in the tutorial, but nothing exhaustive.

[nikomatsakis]

Still, good to know. At least I can point people to http://doc.rust-lang.org/doc/tutorial.html#safe-references

[graydon]

Marking as likely-obsolete / should-close, since I think this component is slated for removal when we move to region-checking for this sort of safety-enforcement. Agreed?

[nikomatsakis]

Agreed.