QDataStream: make qfloat16 streaming a non-member

Remove the member function from the API and re-add it as a hidden
friend on qfloat16, where it will be a complete type.

[ChangeLog][QtCore][Potentially Souce-Incompatible Changes] The
qfloat16 QDataStream operators are now hidden friends and only found
by argument-dependent lookup. Previously, these were member functions
on QDataStream.

Fixes: QTBUG-93499
Pick-to: 6.3
Change-Id: Ib3d4df7a3fe3a9d0938f3be8b70b50fef0416262
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/corelib/compat/removed_api.cpp

@@ -103,6 +103,23 @@ QByteArray QCryptographicHash::hash(const QByteArray &data, Algorithm method)
     return hash(QByteArrayView{data}, method);
 }
 
+#include "qdatastream.h"
+
+# ifndef QT_NO_DATASTREAM
+# include "qfloat16.h"
+
+QDataStream &QDataStream::operator>>(qfloat16 &f)
+{
+    return *this >> reinterpret_cast<qint16&>(f);
+}
+
+QDataStream &QDataStream::operator<<(qfloat16 f)
+{
+    return *this << reinterpret_cast<qint16&>(f);
+}
+
+# endif
+
 #include "quuid.h"
 
 QUuid::QUuid(const QString &text)

src/corelib/global/qfloat16.cpp

@@ -42,6 +42,8 @@
 #include "private/qsimd_p.h"
 #include <cmath> // for fpclassify()'s return values
 
+#include <QtCore/qdatastream.h>
+
 QT_BEGIN_NAMESPACE
 
 QT_IMPL_METATYPE_EXTERN(qfloat16)
@@ -394,6 +396,41 @@ Q_CORE_EXPORT void qFloatFromFloat16(float *out, const qfloat16 *in, qsizetype l
         out[i] = float(in[i]);
 }
 
+#ifndef QT_NO_DATASTREAM
+/*!
+    \fn qfloat16::operator<<(QDataStream &ds, qfloat16 f)
+    \relates QDataStream
+    \since 5.9
+
+    Writes a floating point number, \a f, to the stream \a ds using
+    the standard IEEE 754 format. Returns a reference to the stream.
+
+    \note In Qt versions prior to 6.3, this was a member function on
+    QDataStream.
+*/
+QDataStream &operator<<(QDataStream &ds, qfloat16 f)
+{
+    return ds << f.b16;
+}
+
+/*!
+    \fn qfloat16::operator>>(QDataStream &ds, qfloat16 &f)
+    \relates QDataStream
+    \since 5.9
+
+    Reads a floating point number from the stream \a ds into \a f,
+    using the standard IEEE 754 format. Returns a reference to the
+    stream.
+
+    \note In Qt versions prior to 6.3, this was a member function on
+    QDataStream.
+*/
+QDataStream &operator>>(QDataStream &ds, qfloat16 &f)
+{
+    return ds >> f.b16;
+}
+#endif
+
 QT_END_NAMESPACE
 
 #include "qfloat16tables.cpp"

src/corelib/global/qfloat16.h

@@ -67,6 +67,10 @@ QT_BEGIN_NAMESPACE
 #pragma qt_no_master_include
 #endif
 
+#ifndef QT_NO_DATASTREAM
+class QDataStream;
+#endif
+
 class qfloat16
 {
     struct Wrap
@@ -200,6 +204,11 @@ QT_WARNING_DISABLE_FLOAT_COMPARE
 #undef QF16_MAKE_BOOL_OP_INT
 
 QT_WARNING_POP
+
+#ifndef QT_NO_DATASTREAM
+    friend Q_CORE_EXPORT QDataStream &operator<<(QDataStream &ds, qfloat16 f);
+    friend Q_CORE_EXPORT QDataStream &operator>>(QDataStream &ds, qfloat16 &f);
+#endif
 };
 
 Q_DECLARE_TYPEINFO(qfloat16, Q_PRIMITIVE_TYPE);

src/corelib/serialization/qdatastream.cpp

@@ -991,20 +991,6 @@ QDataStream &QDataStream::operator>>(double &f)
 }
 
 
-/*!
-    \overload
-    \since 5.9
-
-    Reads a floating point number from the stream into \a f,
-    using the standard IEEE 754 format. Returns a reference to the
-    stream.
-*/
-QDataStream &QDataStream::operator>>(qfloat16 &f)
-{
-    return *this >> reinterpret_cast<qint16&>(f);
-}
-
-
 /*!
     \overload
 
@@ -1340,19 +1326,6 @@ QDataStream &QDataStream::operator<<(double f)
 }
 
 
-/*!
-    \fn QDataStream &QDataStream::operator<<(qfloat16 f)
-    \overload
-    \since 5.9
-
-    Writes a floating point number, \a f, to the stream using
-    the standard IEEE 754 format. Returns a reference to the stream.
-*/
-QDataStream &QDataStream::operator<<(qfloat16 f)
-{
-    return *this << reinterpret_cast<qint16&>(f);
-}
-
 /*!
     \overload
 

src/corelib/serialization/qdatastream.h

@@ -51,7 +51,9 @@
 
 QT_BEGIN_NAMESPACE
 
+#if QT_CORE_REMOVED_SINCE(6, 3)
 class qfloat16;
+#endif
 class QByteArray;
 class QIODevice;
 
@@ -160,8 +162,9 @@ public:
     QDataStream &operator>>(std::nullptr_t &ptr) { ptr = nullptr; return *this; }
 
     QDataStream &operator>>(bool &i);
-    // ### Qt 7: remove the operator or make qfloat16 fully defined, see QTBUG-93499
+#if QT_CORE_REMOVED_SINCE(6, 3)
     QDataStream &operator>>(qfloat16 &f);
+#endif
     QDataStream &operator>>(float &f);
     QDataStream &operator>>(double &f);
     QDataStream &operator>>(char *&str);
@@ -179,8 +182,9 @@ public:
     QDataStream &operator<<(quint64 i);
     QDataStream &operator<<(std::nullptr_t) { return *this; }
     QDataStream &operator<<(bool i);
-    // ### Qt 7: remove the operator or make qfloat16 fully defined, see QTBUG-93499
+#if QT_CORE_REMOVED_SINCE(6, 3)
     QDataStream &operator<<(qfloat16 f);
+#endif
     QDataStream &operator<<(float f);
     QDataStream &operator<<(double f);
     QDataStream &operator<<(const char *str);