proc_macro_hack/
error.rs

1use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
2use std::iter::FromIterator;
3
4pub struct Error {
5    span: Span,
6    msg: String,
7}
8
9impl Error {
10    pub fn new(span: Span, msg: impl Into<String>) -> Self {
11        Error {
12            span,
13            msg: msg.into(),
14        }
15    }
16}
17
18pub fn compile_error(err: Error) -> TokenStream {
19    // compile_error!($msg)
20    TokenStream::from_iter(vec![
21        TokenTree::Ident(Ident::new("compile_error", err.span)),
22        TokenTree::Punct({
23            let mut punct = Punct::new('!', Spacing::Alone);
24            punct.set_span(err.span);
25            punct
26        }),
27        TokenTree::Group({
28            let mut group = Group::new(Delimiter::Brace, {
29                TokenStream::from_iter(vec![TokenTree::Literal({
30                    let mut string = Literal::string(&err.msg);
31                    string.set_span(err.span);
32                    string
33                })])
34            });
35            group.set_span(err.span);
36            group
37        }),
38    ])
39}
proc_macro_hack/error.rs

proc_macro_hack/
error.rs
