Fix `-Wnested-anon-types`
Fix `-Wnested-anon-types`

Reviewed By: igorsugak

Differential Revision: D32415926

fbshipit-source-id: b62ac87215800eed8e6cf8acf92f0518b9a56da5

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly