syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // pass non-transparent wrappers around a vector as `PassMode::Cast`
context_before:         if arg.layout.is_single_vector_element(cx, size) {
context_after:             arg.cast_to(Reg { kind: RegKind::Vector, size });