{"ast_node_type":"variable","tokens":[{"end":65,"kind":"keyword","start":0,"text":"let"}]}
        let expr_ty = fcx.resolve_vars_if_possible(self.expr_ty);
        let cast_span = self.expr_span.shrink_to_hi().to(self.cast_span);
        let cast_ty = fcx.resolve_vars_if_possible(self.cast_ty);