1use crate::ToTokens;
2use proc_macro2::extra::DelimSpan;
3use proc_macro2::{Span, TokenStream};
4
5// Not public API other than via the syn crate. Use syn::spanned::Spanned.
6pub trait Spanned: private::Sealed {
7 fn __span(&self) -> Span;
8}
9
10impl Spanned for Span {
11 fn __span(&self) -> Span {
12 *self
13 }
14}
15
16impl Spanned for DelimSpan {
17 fn __span(&self) -> Span {
18 self.join()
19 }
20}
21
22impl<T: ?Sized + ToTokens> Spanned for T {
23 fn __span(&self) -> Span {
24 join_spans(self.into_token_stream())
25 }
26}
27
28fn join_spans(tokens: TokenStream) -> Span {
29 #[cfg(not(needs_invalid_span_workaround))]
30 let mut iter: impl Iterator = tokens.into_iter().map(|tt: TokenTree| tt.span());
31
32 #[cfg(needs_invalid_span_workaround)]
33 let mut iter = tokens.into_iter().filter_map(|tt| {
34 let span = tt.span();
35 let debug = format!("{:?}", span);
36 if debug.ends_with("bytes(0..0)") {
37 None
38 } else {
39 Some(span)
40 }
41 });
42
43 let first: Span = match iter.next() {
44 Some(span: Span) => span,
45 None => return Span::call_site(),
46 };
47
48 iter.fold(None, |_prev, next| Some(next))
49 .and_then(|last| first.join(last))
50 .unwrap_or(default:first)
51}
52
53mod private {
54 use crate::ToTokens;
55 use proc_macro2::extra::DelimSpan;
56 use proc_macro2::Span;
57
58 pub trait Sealed {}
59 impl Sealed for Span {}
60 impl Sealed for DelimSpan {}
61 impl<T: ?Sized + ToTokens> Sealed for T {}
62}
63