syntax_data: {"ast_node_type":"other","tokens":[{"end":49,"kind":"keyword","start":0,"text":"u128::from(idx.as_u32()),"}]}
source_snippet:                         u128::from(idx.as_u32()),
context_before:                         layout.ty.discriminant_for_variant(tcx, idx).unwrap().val,
context_after:                     );