syntax_data: {"ast_node_type":"other","tokens":[{"end":62,"kind":"keyword","start":0,"text":"ExprKind::Use"}]}
source_snippet:             ExprKind::Use { source: self.mirror_expr(source) }
context_before:             // Convert the lexpr to a vexpr.
context_after:         } else if self.typeck_results.expr_ty(source).is_ref() {