Valentin Shergin d16772a31e Sealable: fixed semantic; atomic type for the flag variable
Summary:
* Fixed semantic: all kinds of derivative instances lose `sealed` flag (which is expected);
 * Using atomic<bool> for `sealed_` ivar.

Reviewed By: fkgozali

Differential Revision: D7230674

fbshipit-source-id: abe786610c20a45a0fabb9068120e24adeeeac7f
2018-03-18 19:17:39 -07:00
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2018-03-08 18:04:28 -08:00