syntax_data: {"ast_node_type":"other","tokens":[{"end":46,"kind":"keyword","start":0,"text":"lhs:"}]}
source_snippet:                 lhs: self.mirror_expr(source),
context_before:             hir::ExprKind::Field(source, ..) => ExprKind::Field {
context_after:                 variant_index: FIRST_VARIANT,