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// force-host
// no-prefer-dynamic
#![crate_type = "proc-macro"]
extern crate proc_macro;
use proc_macro::{Group, TokenStream, TokenTree};
// This macro exists as part of a reproduction of #61963 but without using quote/syn/proc_macro2.
#[proc_macro_derive(DomObject)]
pub fn expand_token_stream(input: TokenStream) -> TokenStream {
// Construct a dummy span - `#0 bytes(0..0)` - which is present in the input because
// of the specially crafted generated tokens in the `attribute-crate` proc-macro.
let dummy_span = input.clone().into_iter().nth(0).unwrap().span();
// Define what the macro would output if constructed properly from the source using syn/quote.
let output: TokenStream = "impl Bar for ((), Qux<Qux<Baz> >) { }
impl Bar for ((), Box<Bar>) { }".parse().unwrap();
let mut tokens: Vec<_> = output.into_iter().collect();
// Adjust token spans to match the original crate (which would use `quote`). Some of the
// generated tokens point to the dummy span.
for token in tokens.iter_mut() {
if let TokenTree::Group(group) = token {
let mut tokens: Vec<_> = group.stream().into_iter().collect();
for token in tokens.iter_mut().skip(2) {
token.set_span(dummy_span);
}
let mut stream = TokenStream::new();
stream.extend(tokens);
*group = Group::new(group.delimiter(), stream);
}
}
let mut output = TokenStream::new();
output.extend(tokens);
output
}
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