syntax_data: {"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"base:"}]}
source_snippet:                                     base: self.mirror_expr(base),
context_before:                                 hir::StructTailExpr::Base(base) => AdtExprBase::Base(FruInfo {
context_after:                                     field_types: self.typeck_results.fru_field_types()[expr.hir_id]