Function rustc_ast_pretty::pprust::state::print_crate

pub fn print_crate<'a>(
    sm: &'a SourceMap,
    krate: &Crate,
    filename: FileName,
    input: String,
    ann: &'a dyn PpAnn,
    is_expanded: bool,
    edition: Edition,
    g: &AttrIdGenerator
) -> String

Requires you to pass an input filename and reader so that it can scan the input text for comments to copy forward.