Deprecate constructing QFlags from a pointer

This was used to support QFlags f = 0 initialization, but with 0 used
as a pointer literal now considered bad form, it had been changed many
places to QFlags f = nullptr, which is meaningless and confusing.

Change-Id: I4bc592151c255dc5cab1a232615caecc520f02e8
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 17 insertions, 2 deletions

diff --git a/src/corelib/global/qflags.h b/src/corelib/global/qflags.h
index bd3c219968..4f46de5eaa 100644
--- a/src/corelib/global/qflags.h
+++ b/src/corelib/global/qflags.h
@@ -93,8 +93,10 @@ class QFlags
                       "long long will overflow.");
     Q_STATIC_ASSERT_X((std::is_enum<Enum>::value), "QFlags is only usable on enumeration types.");
 
+#if QT_DEPRECATED_SINCE(5,15)
     struct Private;
     typedef int (Private::*Zero);
+#endif
     template <typename E> friend QDataStream &operator>>(QDataStream &, QFlags<E> &);
     template <typename E> friend QDataStream &operator<<(QDataStream &, QFlags<E>);
 public:
@@ -115,8 +117,11 @@ public:
     Q_DECL_CONSTEXPR inline QFlags(const QFlags &other);
     Q_DECL_CONSTEXPR inline QFlags &operator=(const QFlags &other);
 #endif
+    Q_DECL_CONSTEXPR inline QFlags() noexcept : i(0) {}
     Q_DECL_CONSTEXPR inline QFlags(Enum flags) noexcept : i(Int(flags)) {}
-    Q_DECL_CONSTEXPR inline QFlags(Zero = nullptr) noexcept : i(0) {}
+#if QT_DEPRECATED_SINCE(5,15)
+    QT_DEPRECATED_X("Use default constructor instead") Q_DECL_CONSTEXPR inline QFlags(Zero) noexcept : i(0) {}
+#endif
     Q_DECL_CONSTEXPR inline QFlags(QFlag flag) noexcept : i(flag) {}
 
     Q_DECL_CONSTEXPR inline QFlags(std::initializer_list<Enum> flags) noexcept
diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index 4ab5bd2edb..d95cc786ab 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -250,7 +250,7 @@ Q_STATIC_ASSERT((std::is_same<qsizetype, qptrdiff>::value));
     Qt::Alignment type is simply a typedef for
     QFlags<Qt::AlignmentFlag>. QLabel::setAlignment() takes a
     Qt::Alignment parameter, which means that any combination of
-    Qt::AlignmentFlag values, or 0, is legal:
+    Qt::AlignmentFlag values, or \c{{ }}, is legal:
 
     \snippet code/src_corelib_global_qglobal.cpp 0
 
@@ -318,10 +318,20 @@ Q_STATIC_ASSERT((std::is_same<qsizetype, qptrdiff>::value));
 */
 
 /*!
+    \fn template <typename Enum> QFlags<Enum>::QFlags()
+    \since 5.15
+
+    Constructs a QFlags object with no flags set.
+*/
+
+/*!
     \fn template <typename Enum> QFlags<Enum>::QFlags(Zero)
+    \deprecated
 
     Constructs a QFlags object with no flags set. The parameter must be a
     literal 0 value.
+
+    Deprecated, use default constructor instead.
 */
 
 /*!