Add docs for keywords

[GuillaumeGomez]

Since the #[doc(keyword = "...")] feature has been merged, we can now add documentation for keywords.

cc @rust-lang/docs

[QuietMisdreavus]

Quickly dumping a list of the keywords in the compiler, based on this list. Pretty sure we don't need or want to make a page for all of them, but at least we can start from something. They're broken into sections with their explanatory comment.

"Special reserved identifiers used internally for elided lifetimes,
unnamed method parameters, crate root module, error recovery etc."

• $crate
• _

"Keywords used in the language."

• as (Gradually expanding libstd's keyword documentation #53931)
• box
• break
• const (Gradually expanding libstd's keyword documentation #53931)
• continue
• crate (Gradually expanding libstd's keyword documentation #53931)
• else
• enum (Add enum keyword #53726)
• extern (Gradually expanding libstd's keyword documentation #53931)
• false
• fn
• for (Gradually expanding libstd's keyword documentation #53931)
• if
• impl
• in
• let
• loop
• match
• mod
• move
• mut
• pub
• ref
• return
• self
• Self
• static
• struct
• super
• trait
• true
• type
• unsafe
• use
• where
• while

"Keywords reserved for future use."

• abstract
• become
• do
• final
• macro
• override
• priv
• typeof
• unsized
• virtual
• yield

"Edition-specific keywords reserved for future use."

• async

"Special lifetime names"

• '_
• 'static

"Weak keywords, have special meaning only in specific contexts."

• auto
• catch
• default
• dyn
• union

[GuillaumeGomez]

I'll write the docs for one keyword so then we can open it for newcomers.

[inquisitivecrystal]

@iirelu Which of these were you planning on doing?

[iirelu]

I don't have the free time to write docs any more, so I'm hoping someone else continues where I left off.

[inquisitivecrystal]

Alright, thanks. I may do some then.

[inquisitivecrystal]

I am now working on this.

[inquisitivecrystal]

Sorry for the lack of an update. I don’t have time for this at the moment. If I have a chance, I’ll open a PR with what I have although honestly it's mostly additions to the existing ones rather than anything new.

[DevQps]

Just as an update, some keywords have been fixed:

• const
• if
• enum
• extern
• true/false (are referred to the primitive type boolean)
• as
• crate

[steveklabnik]

Closing as a duplicate of #34601, it's older.