Shorten Associated to Assoc and rename Method to AssocFn.

[eddyb]

We've been moving away from the "static method" terminology, so IMO we should be more uniform with all associated items, and treat the general case of "methods that may or may not have self" as simply "associated functions".
"Method" terminology would then remain primarily for "method call", i.e. dot syntax for asymmetrically providing the self argument.

Because AssociatedFn is a bit long, I'd find it fitting if we shortened Associated, across rustc, to Assoc, so we end up with AssocFn (which only one letter longer than Method).
Also, when Method appears in the context of associated items already (e.g. {Trait,Impl}ItemKind), it can be just Fn.

cc @rust-lang/compiler (and in particular, I'm curious what @nikomatsakis thinks the decision process for "cosmetic" changes like these should be)

[nikomatsakis]

I think that discussing terminology like this is probably a good fit for a design meeting. I also think this particular change is a good idea.

[nikomatsakis]

I've added this to my temporary list of design meeting ideas

[agnxy]

Hi @eddyb @nikomatsakis I'd like to work on this if the decision has been made.

[oli-obk]

@agnxy one thing that doesn't need a decision is to change all things named Associated... to Assoc.... So you can do that already.

[eddyb]

Remaining possible renames:

• associated -> assoc, Associated -> Assoc:

  rust/src/librustc/query/mod.rs

  Lines 374 to 381 in 7520894

  	/// Maps from an impl/trait `DefId to a list of the `DefId`s of its items.
  	query associated_item_def_ids(_: DefId) -> &'tcx [DefId] {}
  	/// Maps from a trait item to the trait item "descriptor".
  	query associated_item(_: DefId) -> ty::AssocItem {}
  	/// Collects the associated items defined on a trait or impl.
  	query associated_items(key: DefId) -> &'tcx ty::AssociatedItems {

• Method -> Fn:

  rust/src/librustc/ty/mod.rs

  Lines 203 to 208 in 7520894

  	pub enum AssocKind {
  	Const,
  	Method,
  	OpaqueTy,
  	Type,
  	}

• method -> fn:

  rust/src/librustc/ty/mod.rs

  Lines 197 to 199 in 7520894

  	/// Whether this is a method with an explicit self
  	/// as its first argument, allowing method calls.
  	pub method_has_self_argument: bool,

There's also things like rustc_typeck::check::compare_method that could be called something like compare_assoc but ideally it would be clearer that it validates impl assoc items against trait ones, for matching signature/type, where clauses, etc. (cc @nikomatsakis)

[nikomatsakis]

Note: as part of the effort to "extract a shared library for types", I want to do a review of naming conventions for things like this and try to reach some decisions.

[nikomatsakis]

I have mixed feelings about "shortening things" like Assoc. I do appreciate it being concise, but I also think that writing things out has a surprisingly nice effect on things feeling more readable overall.

[nikomatsakis]

But I think that using "associated function" instead of "method" is perhaps wise, particularly if it applies uniformly to things with &self and without.