fn parse_source(
source: &str,
crate_name: &Option<&str>,
parent_dcx: Option<DiagCtxtHandle<'_>>,
span: Span,
) -> Result<ParseSourceInfo, ()>
fn parse_source(
source: &str,
crate_name: &Option<&str>,
parent_dcx: Option<DiagCtxtHandle<'_>>,
span: Span,
) -> Result<ParseSourceInfo, ()>