rust: Update `builtins` and sample file

[nsfisis]

Lexer

rust

Versions

• Rouge: 4.0.1
• Rust: 1.66

Problems

• Rouge::Lexers::Rust#builtins()
  • The list has many removed structs/traits.
  • Some important built-in items are not included.
• The sample file, spec/visual/samples/rust
  • It is written in very old version of Rust (pre-1.0, I guess).

Proposals

The built-in items

Things that should be removed

• Cons
• Const
• Either
• Failure
• Gc
• Left
• Modulo
• Nil
• Num
• Ptr
• Right
• Success

These structs or traits are not defined in newer versions of Rust, at least v1.66.

Things that should be added

Based on std::prelude: https://doc.rust-lang.org/std/prelude/index.html

• FromIterator
• ToOwned
• ToString
• TryFrom
• TryInto

You can use any items in std::prelude module without importing.

The sample file

The sample file may be written in pre-1.0 Rust.

• io::println => println!
  • Removed function
• impl<A> &[A]: iterable<A> { ... } => impl<A> iterable<A> for &[A] { ... }
  • Removed syntax
• for vec::each(self) |e| { ... } => for e in v.iter() { ... }
  • Removed syntax
• assert some_expr => assert!(some_expr)
  • Removed syntax
• 5...6 => 5..=6
  • Removed syntax
• tag(~str, ~[HTMLFragment]) => Tag(String, Vec<Box<HTMLFragment>>)
  • Removed syntax

EDIT:

• fn<'a> pointer(&'a u32) {} => fn pointer<'a>(n: &'a u32) {}
  • Removed syntax
• int => i32
  • Removed type
• uint => usize
  • Removed type