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#![feature(proc_macro_diagnostic, proc_macro_span)]
extern crate proc_macro;
use proc_macro::{TokenStream, TokenTree, Span};
fn lit_span(tt: TokenTree) -> (Span, String) {
match tt {
TokenTree::Literal(..) |
TokenTree::Group(..) => (tt.span(), tt.to_string().trim().into()),
_ => panic!("expected a literal in token tree, got: {:?}", tt)
}
}
#[proc_macro]
pub fn parent_source_spans(input: TokenStream) -> TokenStream {
let mut tokens = input.into_iter();
let (sp1, str1) = lit_span(tokens.next().expect("first string"));
let _ = tokens.next();
let (sp2, str2) = lit_span(tokens.next().expect("second string"));
sp1.error(format!("first final: {}", str1)).emit();
sp2.error(format!("second final: {}", str2)).emit();
if let (Some(p1), Some(p2)) = (sp1.parent(), sp2.parent()) {
p1.error(format!("first parent: {}", str1)).emit();
p2.error(format!("second parent: {}", str2)).emit();
if let (Some(gp1), Some(gp2)) = (p1.parent(), p2.parent()) {
gp1.error(format!("first grandparent: {}", str1)).emit();
gp2.error(format!("second grandparent: {}", str2)).emit();
}
}
sp1.source().error(format!("first source: {}", str1)).emit();
sp2.source().error(format!("second source: {}", str2)).emit();
"ok".parse().unwrap()
}
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