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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libstdc++/103629] Possible miscompilation visible using pthread
 + exception
Date: Fri, 10 Dec 2021 15:28:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103629

--- Comment #17 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The difference is due to this change in std::call_once


-      __once_callable =3D std::__addressof(__callable); // NOLINT: PR 82481
-      __once_call =3D []{ (*(decltype(__callable)*)__once_callable)(); };
+      once_flag::_Prepare_execution __exec(__callable);

But I don't know why.=