File: hygiene_example_codegen.rs

package info (click to toggle)
rustc 1.85.0%2Bdfsg3-1
  • links: PTS, VCS
  • area: main
  • in suites: experimental, sid, trixie
  • size: 893,396 kB
  • sloc: xml: 158,127; python: 35,830; javascript: 19,497; cpp: 19,002; sh: 17,245; ansic: 13,127; asm: 4,376; makefile: 1,051; perl: 29; lisp: 29; ruby: 19; sql: 11
file content (23 lines) | stat: -rw-r--r-- 762 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
#![feature(proc_macro_quote)]

extern crate proc_macro as proc_macro_renamed; // This does not break `quote!`

use proc_macro_renamed::{TokenStream, quote};

#[proc_macro]
pub fn hello(input: TokenStream) -> TokenStream {
    quote!(hello_helper!($input))
    //^ `hello_helper!` always resolves to the following proc macro,
    //| no matter where `hello!` is used.
}

#[proc_macro]
pub fn hello_helper(input: TokenStream) -> TokenStream {
    quote! {
        extern crate hygiene_example; // This is never a conflict error
        let string = format!("hello {}", $input);
        //^ `format!` always resolves to the prelude macro,
        //| even if a different `format!` is in scope where `hello!` is used.
        hygiene_example::print(&string)
    }
}