syntax_data: {"ast_node_type":"other","tokens":[{"end":74,"kind":"keyword","start":0,"text":"tag:"}]}
source_snippet:             tag: Option<(ScalarInt, VariantIdx, TagEncoding<VariantIdx>)>,
context_before:             def: Def<'tcx>,
context_after:             (ty, layout): (Ty<'tcx>, Layout<'tcx>),