37ed2ab910
Implements RFC 1576. See: https://github.com/rust-lang/rfcs/blob/master/text/1576-macros-literal-matcher.md Changes are mostly in libsyntax, docs, and tests. Feature gate is enabled for 1.27.0. Many thanks to Vadim Petrochenkov for following through code reviews and suggestions. Example: ````rust macro_rules! test_literal { ($l:literal) => { println!("literal: {}", $l); }; ($e:expr) => { println!("expr: {}", $e); }; } fn main() { let a = 1; test_literal!(a); test_literal!(2); test_literal!(-3); } ``` Output: ``` expr: 1 literal: 2 literal: -3 ```