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Harold Pratt
e7a8d21df5
Summary: C++ does not, pedantically, allow the use of unions for type-punning in the way that C does. Most compilers, in practice, do support it; however, recent versions of MSVC appear to have a bug that cause bad code to be generated due to this U.B. (see: https://developercommunity.visualstudio.com/t/Bad-code-generated-for-std::isnan-compil/10082631). This led to a series of issues in the react-native-windows project, see: * https://github.com/microsoft/react-native-windows/issues/4122 * https://github.com/microsoft/react-native-windows/issues/8675 In C++20, the `<bit>` header and `bit_cast` function provide a pleasant API for type-punning. Since C++20 is not universally available, if the feature-test macro for `bit_cast` is not defined, memcpy is used instead. X-link: https://github.com/facebook/yoga/pull/1154 Reviewed By: Andrey-Mishanin Differential Revision: D38082048 Pulled By: rozele fbshipit-source-id: a5da08cfb7d4296c725fb44871c55dbb12dc71e5