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Fix pointer offset loss in OwnerPtr::Cast and ShadowPtr::Shadow under multiple inheritance #10

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Merged
zhuuuoyue merged 2 commits into from
Apr 8, 2026
Merged

Fix pointer offset loss in OwnerPtr::Cast and ShadowPtr::Shadow under multiple inheritance #10

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eb2c240
Initial plan
Copilot Apr 8, 2026
6421e0f
Fix pointer offset bug: use dual-pointer design in OwnerPtr and Shado…
Copilot Apr 8, 2026
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77 changes: 53 additions & 24 deletions include/PrettyMemory.h
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,7 @@ namespace prtm
{
if (other.m_pControlBlock)
{
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
++m_pControlBlock->ShadowCount;
}
Expand All @@ -94,6 +95,7 @@ namespace prtm
{
if (other.m_pControlBlock)
{
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
++m_pControlBlock->ShadowCount;
}
Expand All @@ -107,7 +109,9 @@ namespace prtm
template<typename T2 = T, std::enable_if_t<std::is_convertible_v<T2*, T*>, int> = 0>
ShadowPtr(ShadowPtr<T2>&& other) noexcept
{
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
other.m_pTyped = nullptr;
other.m_pControlBlock = nullptr;
}

Expand All @@ -121,6 +125,7 @@ namespace prtm
if (this != &other)
{
Destroy();
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
if (m_pControlBlock)
{
Expand All @@ -142,6 +147,7 @@ namespace prtm
if (static_cast<const void*>(this) != static_cast<const void*>(&other))
{
Destroy();
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
if (m_pControlBlock)
{
Expand All @@ -161,7 +167,9 @@ namespace prtm
if (this != &other)
{
Destroy();
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
other.m_pTyped = nullptr;
other.m_pControlBlock = nullptr;
}
return *this;
Expand All @@ -179,7 +187,9 @@ namespace prtm
if (static_cast<const void*>(this) != static_cast<const void*>(&other))
{
Destroy();
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
other.m_pTyped = nullptr;
other.m_pControlBlock = nullptr;
}
return *this;
Expand All @@ -192,10 +202,10 @@ namespace prtm
std::size_t ShadowCount() const { return m_pControlBlock ? m_pControlBlock->ShadowCount : 0; }

/** @brief Get the writable raw pointer, or nullptr if the object has expired. */
Pointer Get() { return m_pControlBlock ? static_cast<Pointer>(m_pControlBlock->Data) : nullptr; }
Pointer Get() { return (m_pControlBlock && m_pControlBlock->Data) ? m_pTyped : nullptr; }

/** @brief Get the const raw pointer, or nullptr if the object has expired. */
ConstPointer Get() const { return m_pControlBlock ? static_cast<ConstPointer>(m_pControlBlock->Data) : nullptr; }
ConstPointer Get() const { return (m_pControlBlock && m_pControlBlock->Data) ? m_pTyped : nullptr; }

/** @brief Get the writable data pointer. */
Pointer Data() { return Get(); }
Expand Down Expand Up @@ -230,6 +240,7 @@ namespace prtm
*/
void Swap(ShadowPtr& other) noexcept
{
std::swap(m_pTyped, other.m_pTyped);
std::swap(m_pControlBlock, other.m_pControlBlock);
}

Expand All @@ -249,10 +260,12 @@ namespace prtm
}
m_pControlBlock = nullptr;
}
m_pTyped = nullptr;
}

private:

Pointer m_pTyped{ nullptr };
detail::ControlBlock* m_pControlBlock{ nullptr };
};

Expand Down Expand Up @@ -316,28 +329,28 @@ namespace prtm
template<typename T>
bool operator<(const ShadowPtr<T>& lhs, std::nullptr_t)
{
return lhs.Get() < nullptr;
return lhs.Get() < static_cast<typename ShadowPtr<T>::ConstPointer>(nullptr);
}

/** @brief Compare a ShadowPtr with nullptr by raw pointer address. */
template<typename T>
bool operator<=(const ShadowPtr<T>& lhs, std::nullptr_t)
{
return lhs.Get() <= nullptr;
return lhs.Get() <= static_cast<typename ShadowPtr<T>::ConstPointer>(nullptr);
}

/** @brief Compare a ShadowPtr with nullptr by raw pointer address. */
template<typename T>
bool operator>(const ShadowPtr<T>& lhs, std::nullptr_t)
{
return lhs.Get() > nullptr;
return lhs.Get() > static_cast<typename ShadowPtr<T>::ConstPointer>(nullptr);
}

/** @brief Compare a ShadowPtr with nullptr by raw pointer address. */
template<typename T>
bool operator>=(const ShadowPtr<T>& lhs, std::nullptr_t)
{
return lhs.Get() >= nullptr;
return lhs.Get() >= static_cast<typename ShadowPtr<T>::ConstPointer>(nullptr);
}

/** @brief Compare nullptr with a ShadowPtr. */
Expand All @@ -358,28 +371,28 @@ namespace prtm
template<typename T>
bool operator<(std::nullptr_t, const ShadowPtr<T>& rhs)
{
return nullptr < rhs.Get();
return static_cast<typename ShadowPtr<T>::ConstPointer>(nullptr) < rhs.Get();
}

/** @brief Compare nullptr with a ShadowPtr by raw pointer address. */
template<typename T>
bool operator<=(std::nullptr_t, const ShadowPtr<T>& rhs)
{
return nullptr <= rhs.Get();
return static_cast<typename ShadowPtr<T>::ConstPointer>(nullptr) <= rhs.Get();
}

/** @brief Compare nullptr with a ShadowPtr by raw pointer address. */
template<typename T>
bool operator>(std::nullptr_t, const ShadowPtr<T>& rhs)
{
return nullptr > rhs.Get();
return static_cast<typename ShadowPtr<T>::ConstPointer>(nullptr) > rhs.Get();
}

/** @brief Compare nullptr with a ShadowPtr by raw pointer address. */
template<typename T>
bool operator>=(std::nullptr_t, const ShadowPtr<T>& rhs)
{
return nullptr >= rhs.Get();
return static_cast<typename ShadowPtr<T>::ConstPointer>(nullptr) >= rhs.Get();
}

/**
Expand All @@ -401,6 +414,7 @@ namespace prtm
}

ShadowPtr<T> shadow;
shadow.m_pTyped = static_cast<T*>(this);
shadow.m_pControlBlock = m_pControlBlock;
++m_pControlBlock->ShadowCount;
return shadow;
Expand All @@ -416,6 +430,7 @@ namespace prtm
}

ShadowPtr<T> shadow;
shadow.m_pTyped = const_cast<T*>(static_cast<const T*>(this));
shadow.m_pControlBlock = m_pControlBlock;
++m_pControlBlock->ShadowCount;
return shadow;
Expand Down Expand Up @@ -467,7 +482,6 @@ namespace prtm
using ConstPointer = const ValueType*;
using Reference = ValueType&;
using ConstReference = const ValueType&;
using DeleterType = DT;

template<typename>
friend class ShadowPtr;
Expand Down Expand Up @@ -508,6 +522,7 @@ namespace prtm
{
if (pOther)
{
m_pTyped = pOther;
m_pControlBlock = new detail::ControlBlock;
m_pControlBlock->Data = pOther;
m_pControlBlock->Deleter = DT2{};
Expand All @@ -531,7 +546,9 @@ namespace prtm
template<typename VT2 = VT, typename DT2 = detail::DefaultDeleter<VT2>, std::enable_if_t<std::is_convertible_v<VT2*, VT*>, int> = 0>
OwnerPtr(OwnerPtr<VT2, DT2>&& other) noexcept
{
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
other.m_pTyped = nullptr;
other.m_pControlBlock = nullptr;
}

Expand All @@ -548,7 +565,9 @@ namespace prtm
if (static_cast<const void*>(this) != static_cast<const void*>(&other))
{
Destroy();
m_pTyped = other.m_pTyped;
m_pControlBlock = other.m_pControlBlock;
other.m_pTyped = nullptr;
other.m_pControlBlock = nullptr;
}
return *this;
Expand All @@ -561,10 +580,10 @@ namespace prtm
std::size_t ShadowCount() const { return m_pControlBlock ? m_pControlBlock->ShadowCount : 0; }

/** @brief Get the writable raw pointer. */
Pointer Get() { return m_pControlBlock ? static_cast<Pointer>(m_pControlBlock->Data) : nullptr; }
Pointer Get() { return m_pTyped; }

/** @brief Get the const raw pointer. */
ConstPointer Get() const { return m_pControlBlock ? static_cast<ConstPointer>(m_pControlBlock->Data) : nullptr; }
ConstPointer Get() const { return m_pTyped; }

/** @brief Get the writable data pointer. */
Pointer Data() { return Get(); }
Expand Down Expand Up @@ -611,6 +630,7 @@ namespace prtm
Destroy();
if (nullptr != pNew)
{
m_pTyped = pNew;
m_pControlBlock = new detail::ControlBlock;
m_pControlBlock->Data = pNew;
m_pControlBlock->Deleter = DT2{};
Expand All @@ -620,7 +640,7 @@ namespace prtm
/** @brief Release ownership and return the raw pointer. */
[[nodiscard]] Pointer Release()
{
Pointer pReleased = Get();
Pointer pReleased = m_pTyped;
if (m_pControlBlock)
{
m_pControlBlock->Data = nullptr;
Expand All @@ -630,6 +650,7 @@ namespace prtm
}
m_pControlBlock = nullptr;
}
m_pTyped = nullptr;
return pReleased;
}

Expand All @@ -641,6 +662,7 @@ namespace prtm
template<typename DT2 = DT>
void Swap(OwnerPtr<VT, DT2>& other) noexcept
{
std::swap(m_pTyped, other.m_pTyped);
std::swap(m_pControlBlock, other.m_pControlBlock);
}

Expand All @@ -656,7 +678,9 @@ namespace prtm
OwnerPtr<VT2, DT2> transferred;
if (m_pControlBlock)
{
transferred.m_pTyped = m_pTyped;
transferred.m_pControlBlock = m_pControlBlock;
m_pTyped = nullptr;
m_pControlBlock = nullptr;
}
return transferred;
Expand All @@ -672,11 +696,12 @@ namespace prtm
[[nodiscard]] OwnerPtr<VT2, DT2> Cast()
{
OwnerPtr<VT2, DT2> casted;
Pointer pCurrent = Get();
typename OwnerPtr<VT2, DT2>::Pointer pCasted = dynamic_cast<typename OwnerPtr<VT2, DT2>::Pointer>(pCurrent);
typename OwnerPtr<VT2, DT2>::Pointer pCasted = dynamic_cast<typename OwnerPtr<VT2, DT2>::Pointer>(m_pTyped);
if (pCasted)
{
casted.m_pTyped = pCasted;
casted.m_pControlBlock = m_pControlBlock;
m_pTyped = nullptr;
m_pControlBlock = nullptr;
}
else
Expand All @@ -697,6 +722,7 @@ namespace prtm
ShadowPtr<VT2> shadow;
if (m_pControlBlock)
{
shadow.m_pTyped = m_pTyped;
shadow.m_pControlBlock = m_pControlBlock;
++m_pControlBlock->ShadowCount;
}
Expand All @@ -714,6 +740,7 @@ namespace prtm
ShadowPtr<VT2> shadow;
if (m_pControlBlock)
{
shadow.m_pTyped = m_pTyped;
shadow.m_pControlBlock = m_pControlBlock;
++m_pControlBlock->ShadowCount;
}
Expand All @@ -737,10 +764,12 @@ namespace prtm
}
m_pControlBlock = nullptr;
}
m_pTyped = nullptr;
}

private:

Pointer m_pTyped{ nullptr };
detail::ControlBlock* m_pControlBlock{ nullptr };
};

Expand Down Expand Up @@ -804,28 +833,28 @@ namespace prtm
template<typename VT, typename DT = detail::DefaultDeleter<VT>>
bool operator<(const OwnerPtr<VT, DT>& lhs, std::nullptr_t)
{
return lhs.Get() < nullptr;
return lhs.Get() < static_cast<typename OwnerPtr<VT, DT>::ConstPointer>(nullptr);
}

/** @brief Compare an OwnerPtr with nullptr by raw pointer address. */
template<typename VT, typename DT = detail::DefaultDeleter<VT>>
bool operator>(const OwnerPtr<VT, DT>& lhs, std::nullptr_t)
{
return lhs.Get() > nullptr;
return lhs.Get() > static_cast<typename OwnerPtr<VT, DT>::ConstPointer>(nullptr);
}

/** @brief Compare an OwnerPtr with nullptr by raw pointer address. */
template<typename VT, typename DT = detail::DefaultDeleter<VT>>
bool operator<=(const OwnerPtr<VT, DT>& lhs, std::nullptr_t)
{
return lhs.Get() <= nullptr;
return lhs.Get() <= static_cast<typename OwnerPtr<VT, DT>::ConstPointer>(nullptr);
}

/** @brief Compare an OwnerPtr with nullptr by raw pointer address. */
template<typename VT, typename DT = detail::DefaultDeleter<VT>>
bool operator>=(const OwnerPtr<VT, DT>& lhs, std::nullptr_t)
{
return lhs.Get() >= nullptr;
return lhs.Get() >= static_cast<typename OwnerPtr<VT, DT>::ConstPointer>(nullptr);
}

/** @brief Compare nullptr with an OwnerPtr. */
Expand All @@ -846,28 +875,28 @@ namespace prtm
template<typename VT, typename DT = detail::DefaultDeleter<VT>>
bool operator<(std::nullptr_t, const OwnerPtr<VT, DT>& rhs)
{
return nullptr < rhs.Get();
return static_cast<typename OwnerPtr<VT, DT>::ConstPointer>(nullptr) < rhs.Get();
}

/** @brief Compare nullptr with an OwnerPtr by raw pointer address. */
template<typename VT, typename DT = detail::DefaultDeleter<VT>>
bool operator>(std::nullptr_t, const OwnerPtr<VT, DT>& rhs)
{
return nullptr > rhs.Get();
return static_cast<typename OwnerPtr<VT, DT>::ConstPointer>(nullptr) > rhs.Get();
}

/** @brief Compare nullptr with an OwnerPtr by raw pointer address. */
template<typename VT, typename DT = detail::DefaultDeleter<VT>>
bool operator<=(std::nullptr_t, const OwnerPtr<VT, DT>& rhs)
{
return nullptr <= rhs.Get();
return static_cast<typename OwnerPtr<VT, DT>::ConstPointer>(nullptr) <= rhs.Get();
}

/** @brief Compare nullptr with an OwnerPtr by raw pointer address. */
template<typename VT, typename DT = detail::DefaultDeleter<VT>>
bool operator>=(std::nullptr_t, const OwnerPtr<VT, DT>& rhs)
{
return nullptr >= rhs.Get();
return static_cast<typename OwnerPtr<VT, DT>::ConstPointer>(nullptr) >= rhs.Get();
}
}

Expand Down
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