use proc_macro2::{Ident, Span, TokenStream};
use quote::{ToTokens, quote};

struct Private;

impl ToTokens for Private {
    fn to_tokens(&self, tokens: &mut TokenStream) {
        Ident::new("private", Span::call_site()).to_tokens(tokens);
    }
}

fn main() {
    let _ = quote! {
        // Okay
        ... #Private ...
    };

    let iter = vec!['0', '1', '2'];
    let _ = quote! {
        // Fail
        #(#Private #iter)*
    };
}