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// compile-flags: --emit=link
// no-prefer-dynamic
#![crate_type = "proc-macro"]
extern crate proc_macro;
use proc_macro::{token_stream, Delimiter, Group, Ident, Span, TokenStream, TokenTree};
fn read_ident(iter: &mut token_stream::IntoIter) -> Ident {
match iter.next() {
Some(TokenTree::Ident(i)) => i,
_ => panic!("expected ident"),
}
}
#[proc_macro_derive(DeriveBadSpan)]
pub fn derive_bad_span(input: TokenStream) -> TokenStream {
let mut input = input.into_iter();
assert_eq!(read_ident(&mut input).to_string(), "struct");
let ident = read_ident(&mut input);
let mut tys = match input.next() {
Some(TokenTree::Group(g)) if g.delimiter() == Delimiter::Parenthesis => g.stream().into_iter(),
_ => panic!(),
};
let field1 = read_ident(&mut tys);
tys.next();
let field2 = read_ident(&mut tys);
<TokenStream as FromIterator<TokenTree>>::from_iter(
[
Ident::new("impl", Span::call_site()).into(),
ident.into(),
Group::new(
Delimiter::Brace,
<TokenStream as FromIterator<TokenTree>>::from_iter(
[
Ident::new("fn", Span::call_site()).into(),
Ident::new("_foo", Span::call_site()).into(),
Group::new(Delimiter::Parenthesis, TokenStream::new()).into(),
Group::new(
Delimiter::Brace,
<TokenStream as FromIterator<TokenTree>>::from_iter(
[
Ident::new("if", field1.span()).into(),
Ident::new("true", field1.span()).into(),
{
let mut group = Group::new(Delimiter::Brace, TokenStream::new());
group.set_span(field1.span());
group.into()
},
Ident::new("if", field2.span()).into(),
Ident::new("true", field2.span()).into(),
{
let mut group = Group::new(Delimiter::Brace, TokenStream::new());
group.set_span(field2.span());
group.into()
},
]
.iter()
.cloned(),
),
)
.into(),
]
.iter()
.cloned(),
),
)
.into(),
]
.iter()
.cloned(),
)
}
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