From 85e4e5bacf0030573359be8de2ea984d541fdbd5 Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Thu, 22 Oct 2020 09:13:24 +0200
Subject: [PATCH] Make QSharedPointer comparisons hidden friends

Doesn't touch qsharedpointer.h which already seems outdated and needs
a general overhaul.

Change-Id: I051cdeb1fe03a7ef16e333a483bb68e2fada3c25
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
---
 src/corelib/tools/qshareddata.cpp       |  34 +++--
 src/corelib/tools/qsharedpointer_impl.h | 158 +++++++-----------------
 2 files changed, 70 insertions(+), 122 deletions(-)

diff --git a/src/corelib/tools/qshareddata.cpp b/src/corelib/tools/qshareddata.cpp
index 6db2a9adb9..16c10a58ac 100644
--- a/src/corelib/tools/qshareddata.cpp
+++ b/src/corelib/tools/qshareddata.cpp
@@ -357,13 +357,23 @@ QT_BEGIN_NAMESPACE
     \since 5.2
 */
 
-/*! \fn template <class T> bool QSharedDataPointer<T>::operator==(const QSharedDataPointer<T>& other) const
-    Returns \c true if \a other and \e this have the same \e{d pointer}.
+/*! \fn template <class T> bool QSharedDataPointer<T>::operator==(const QSharedDataPointer<T>& lhs, const QSharedDataPointer<T>& rhs)
+    Returns \c true if \a lhs and \a rhs have the same \e{d pointer}.
     This function does \e not call detach().
 */
 
-/*! \fn template <class T> bool QSharedDataPointer<T>::operator!=(const QSharedDataPointer<T>& other) const
-    Returns \c true if \a other and \e this do \e not have the same
+/*! \fn template <class T> bool QSharedDataPointer<T>::operator!=(const QSharedDataPointer<T>& lhs, const QSharedDataPointer<T>& rhs)
+    Returns \c true if \a lhs and \a rhs do \e not have the same
+    \e{d pointer}. This function does \e not call detach().
+*/
+
+/*! \fn template <class T> bool QSharedDataPointer<T>::operator==(const T *ptr, const QSharedDataPointer<T>& rhs)
+    Returns \c true if the \e{d pointer} of \a rhs is \a ptr.
+    This function does \e not call detach().
+*/
+
+/*! \fn template <class T> bool QSharedDataPointer<T>::operator!=(const T *ptr, const QSharedDataPointer<T>& rhs)
+    Returns \c true if the \e{d pointer} of \a rhs is \e not \a ptr.
     \e{d pointer}. This function does \e not call detach().
 */
 
@@ -530,8 +540,8 @@ QT_BEGIN_NAMESPACE
   the explicitly shared data pointer in \a other.
  */
 
-/*! \fn template <class T> bool QExplicitlySharedDataPointer<T>::operator==(const QExplicitlySharedDataPointer<T>& other) const
-    Returns \c true if \a other and \e this have the same \e{d pointer}.
+/*! \fn template <class T> bool QExplicitlySharedDataPointer<T>::operator==(const QExplicitlySharedDataPointer<T>& lhs, const QExplicitlySharedDataPointer<T>& rhs)
+    Returns \c true if \a lhs and \a rhs have the same \e{d pointer}.
 */
 
 /*!
@@ -542,17 +552,17 @@ QT_BEGIN_NAMESPACE
     \since 5.2
 */
 
-/*! \fn template <class T> bool QExplicitlySharedDataPointer<T>::operator==(const T* ptr) const
-    Returns \c true if the \e{d pointer} of \e this is \a ptr.
+/*! \fn template <class T> bool QExplicitlySharedDataPointer<T>::operator==(const T* ptr, const QExplicitlySharedDataPointer<T>& rhs)
+    Returns \c true if the \e{d pointer} of \a rhs is \a ptr.
  */
 
-/*! \fn template <class T> bool QExplicitlySharedDataPointer<T>::operator!=(const QExplicitlySharedDataPointer<T>& other) const
-    Returns \c true if \a other and \e this do \e not have the same
+/*! \fn template <class T> bool QExplicitlySharedDataPointer<T>::operator!=(const QExplicitlySharedDataPointer<T>& lhs, const QExplicitlySharedDataPointer<T>& rhs)
+    Returns \c true if \a lhs and \a rhs do \e not have the same
     \e{d pointer}.
 */
 
-/*! \fn template <class T> bool QExplicitlySharedDataPointer<T>::operator!=(const T* ptr) const
-    Returns \c true if the \e{d pointer} of \e this is \e not \a ptr.
+/*! \fn template <class T> bool QExplicitlySharedDataPointer<T>::operator!=(const T* ptr, const QExplicitlySharedDataPointer<T>& rhs)
+    Returns \c true if the \e{d pointer} of \a rhs is \e not \a ptr.
  */
 
 /*! \fn template <class T> QExplicitlySharedDataPointer<T>::QExplicitlySharedDataPointer()
diff --git a/src/corelib/tools/qsharedpointer_impl.h b/src/corelib/tools/qsharedpointer_impl.h
index 2e7ec8103c..affd85d88d 100644
--- a/src/corelib/tools/qsharedpointer_impl.h
+++ b/src/corelib/tools/qsharedpointer_impl.h
@@ -437,6 +437,27 @@ public:
         return result;
     }
 
+#define DECLARE_COMPARE_SET(T1, A1, T2, A2) \
+    friend bool operator==(T1, T2) noexcept \
+    { return A1 == A2; } \
+    friend bool operator!=(T1, T2) noexcept \
+    { return A1 != A2; }
+
+#define DECLARE_TEMPLATE_COMPARE_SET(T1, A1, T2, A2) \
+    template <typename X> \
+    friend bool operator==(T1, T2) noexcept \
+    { return A1 == A2; } \
+    template <typename X> \
+    friend bool operator!=(T1, T2) noexcept \
+    { return A1 != A2; }
+
+    DECLARE_TEMPLATE_COMPARE_SET(const QSharedPointer &p1, p1.data(), const QSharedPointer<X> &p2, p2.data())
+    DECLARE_TEMPLATE_COMPARE_SET(const QSharedPointer &p1, p1.data(), X *ptr, ptr)
+    DECLARE_TEMPLATE_COMPARE_SET(X *ptr, ptr, const QSharedPointer &p2, p2.data())
+    DECLARE_COMPARE_SET(const QSharedPointer &p1, p1.data(), std::nullptr_t, nullptr)
+    DECLARE_COMPARE_SET(std::nullptr_t, nullptr, const QSharedPointer &p2, p2.data())
+#undef DECLARE_TEMPLATE_COMPARE_SET
+
 private:
     explicit QSharedPointer(Qt::Initialization) {}
 
@@ -593,14 +614,6 @@ public:
         return *this;
     }
 
-    template <class X>
-    bool operator==(const QWeakPointer<X> &o) const noexcept
-    { return d == o.d && value == static_cast<const T *>(o.value); }
-
-    template <class X>
-    bool operator!=(const QWeakPointer<X> &o) const noexcept
-    { return !(*this == o); }
-
     template <class X, IfCompatible<X> = true>
     inline QWeakPointer(const QSharedPointer<X> &o) : d(nullptr), value(nullptr)
     { *this = o; }
@@ -612,14 +625,6 @@ public:
         return *this;
     }
 
-    template <class X>
-    bool operator==(const QSharedPointer<X> &o) const noexcept
-    { return d == o.d; }
-
-    template <class X>
-    bool operator!=(const QSharedPointer<X> &o) const noexcept
-    { return !(*this == o); }
-
     inline void clear() { *this = QWeakPointer(); }
 
     inline QSharedPointer<T> toStrongRef() const { return QSharedPointer<T>(*this); }
@@ -630,6 +635,33 @@ public:
     inline T *operator->() const { return data(); }
 #endif
 
+    template <class X>
+    bool operator==(const QWeakPointer<X> &o) const noexcept
+    { return d == o.d && value == static_cast<const T *>(o.value); }
+
+    template <class X>
+    bool operator!=(const QWeakPointer<X> &o) const noexcept
+    { return !(*this == o); }
+
+    template <class X>
+    bool operator==(const QSharedPointer<X> &o) const noexcept
+    { return d == o.d; }
+
+    template <class X>
+    bool operator!=(const QSharedPointer<X> &o) const noexcept
+    { return !(*this == o); }
+
+    template <typename X>
+    friend bool operator==(const QSharedPointer<X> &p1, const QWeakPointer &p2) noexcept
+    { return p2 == p1; }
+    template <typename X>
+    friend bool operator!=(const QSharedPointer<X> &p1, const QWeakPointer &p2) noexcept
+    { return p2 != p1; }
+
+    DECLARE_COMPARE_SET(const QWeakPointer &p1, p1.d, std::nullptr_t, nullptr)
+    DECLARE_COMPARE_SET(std::nullptr_t, nullptr, const QWeakPointer &p2, p2.data())
+#undef DECLARE_COMPARE_SET
+
 private:
     friend struct QtPrivate::EnableInternalData;
 #if defined(Q_NO_TEMPLATE_FRIENDS)
@@ -709,100 +741,6 @@ public:
     mutable QWeakPointer<T> weakPointer;
 };
 
-//
-// operator== and operator!=
-//
-template <class T, class X>
-bool operator==(const QSharedPointer<T> &ptr1, const QSharedPointer<X> &ptr2) noexcept
-{
-    return ptr1.data() == ptr2.data();
-}
-template <class T, class X>
-bool operator!=(const QSharedPointer<T> &ptr1, const QSharedPointer<X> &ptr2) noexcept
-{
-    return ptr1.data() != ptr2.data();
-}
-
-template <class T, class X>
-bool operator==(const QSharedPointer<T> &ptr1, const X *ptr2) noexcept
-{
-    return ptr1.data() == ptr2;
-}
-template <class T, class X>
-bool operator==(const T *ptr1, const QSharedPointer<X> &ptr2) noexcept
-{
-    return ptr1 == ptr2.data();
-}
-template <class T, class X>
-bool operator!=(const QSharedPointer<T> &ptr1, const X *ptr2) noexcept
-{
-    return !(ptr1 == ptr2);
-}
-template <class T, class X>
-bool operator!=(const T *ptr1, const QSharedPointer<X> &ptr2) noexcept
-{
-    return !(ptr2 == ptr1);
-}
-
-template <class T, class X>
-bool operator==(const QSharedPointer<T> &ptr1, const QWeakPointer<X> &ptr2) noexcept
-{
-    return ptr2 == ptr1;
-}
-template <class T, class X>
-bool operator!=(const QSharedPointer<T> &ptr1, const QWeakPointer<X> &ptr2) noexcept
-{
-    return ptr2 != ptr1;
-}
-
-template<class T>
-inline bool operator==(const QSharedPointer<T> &lhs, std::nullptr_t) noexcept
-{
-    return lhs.isNull();
-}
-
-template<class T>
-inline bool operator!=(const QSharedPointer<T> &lhs, std::nullptr_t) noexcept
-{
-    return !lhs.isNull();
-}
-
-template<class T>
-inline bool operator==(std::nullptr_t, const QSharedPointer<T> &rhs) noexcept
-{
-    return rhs.isNull();
-}
-
-template<class T>
-inline bool operator!=(std::nullptr_t, const QSharedPointer<T> &rhs) noexcept
-{
-    return !rhs.isNull();
-}
-
-template<class T>
-inline bool operator==(const QWeakPointer<T> &lhs, std::nullptr_t) noexcept
-{
-    return lhs.isNull();
-}
-
-template<class T>
-inline bool operator!=(const QWeakPointer<T> &lhs, std::nullptr_t) noexcept
-{
-    return !lhs.isNull();
-}
-
-template<class T>
-inline bool operator==(std::nullptr_t, const QWeakPointer<T> &rhs) noexcept
-{
-    return rhs.isNull();
-}
-
-template<class T>
-inline bool operator!=(std::nullptr_t, const QWeakPointer<T> &rhs) noexcept
-{
-    return !rhs.isNull();
-}
-
 //
 // operator-
 //