Function rustc_ap_rustc_parse::new_sub_parser_from_file

pub fn new_sub_parser_from_file<'a>(
    sess: &'a ParseSess, 
    path: &Path, 
    directory_ownership: DirectoryOwnership, 
    module_name: Option<String>, 
    sp: Span
) -> Parser<'a>

Given a session, a crate config, a path, and a span, add the file at the given path to the source_map, and returns a parser. On an error, uses the given span as the source of the problem.