syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // The discriminant is less wide than the operand, cast the operand into
context_before:     let (cast_kind, discr_ty_bits) = if discr.size.bytes() < op_size.bytes() {
context_after:         // [MaybeUninit; N] and then index into it.