Multiline closure body parenthesization can cause incorrect precedence

[dtolnay]

fn main() {
    let input: syn::File = syn::parse_quote! {
        const _: _ = || { a; } .. b .. c;
    };
    println!("syn: {}", quote::ToTokens::to_token_stream(&input));
    print!("prettyplease: {}", prettyplease::unparse(&input));
}

syn: const _ : _ = | | { a ; } .. b .. c ;
prettyplease: const _: _ = || (
    {
        a;
    }..b
)..c;

Due to ridiculous bailout rules, the ..c in the input is outside the closure body. In the output printed by prettyplease, the ..c winds up inside the closure body.