{"ast_node_type":"function","tokens":[{"end":74,"kind":"keyword","start":0,"text":"fn"}]}
    fn location_triple_for_span(&self, span: Span) -> (Symbol, u32, u32) {
impl<'tcx> CompileTimeInterpCx<'tcx> {
        let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);