Function ident_show

pub fn ident_show()

标识符:

let thinking = "thinking";
let thinking123_ = "thinking 123";

// error: invalid suffix `thinking` for integer literal
// let 321_thinking = "thinking";

// ok
let _321_thinking = "thinking";

// non-ascii ident
// RFC: https://github.com/rust-lang/rfcs/blob/master/text/2457-non-ascii-idents.md
// error: unknown start of token: \u{1f914}
//  let 🤔 = "thinking ";