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Fix undefined behavior in PxUnionCast #65

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Fix undefined behavior in PxUnionCast #65

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21 changes: 11 additions & 10 deletions PxShared/include/foundation/PxUnionCast.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,9 @@
#ifndef PXFOUNDATION_PXUNIONCAST_H
#define PXFOUNDATION_PXUNIONCAST_H

#include <cstring>
#include <type_traits>

#include "foundation/Px.h"

/** \addtogroup foundation
Expand All @@ -42,17 +45,15 @@ namespace physx
#endif

template <class A, class B>
PX_FORCE_INLINE A PxUnionCast(B b)
PX_FORCE_INLINE A PxUnionCast(B source)
{
union AB
{
AB(B bb) : _b(bb)
{
}
B _b;
A _a;
} u(b);
return u._a;
static_assert(std::is_trivial<A>::value, "Destination type must be trivial.");
static_assert(std::is_trivial<B>::value, "Source type must be trivial.");
A dest{};

std::memcpy(&dest, &source,
sizeof(dest) <= sizeof(source) ? sizeof(dest) : sizeof(source));
return dest;
}

#if !PX_DOXYGEN
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