qtextstream.h: streamline includes

[ChangeLog][Potentially Source-Incompatible Changes] The qtextstream
header no longer includes <QString>, <QStringEncoder> and
<QStringDecoder>. Code which relied on the implicit inclusion of those
classes might now need to include the headers explicitly.

Task-number: QTBUG-97601
Change-Id: Ifb8c8452026195a772c0588dbbbc53fb51cac548
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

7 files changed, 208 insertions, 136 deletions

diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index be4bc7b2de..0c15c543f1 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -180,6 +180,7 @@ qt_internal_add_module(Core
         text/qstring.cpp text/qstring.h
         text/qstringalgorithms.h text/qstringalgorithms_p.h
         text/qstringbuilder.cpp text/qstringbuilder.h
+        text/qstringconverter_base.h
         text/qstringconverter.cpp text/qstringconverter.h text/qstringconverter_p.h
         text/qstringiterator_p.h
         text/qstringlist.cpp text/qstringlist.h
diff --git a/src/corelib/serialization/qtextstream.h b/src/corelib/serialization/qtextstream.h
index e69c6a67dc..33d5b57018 100644
--- a/src/corelib/serialization/qtextstream.h
+++ b/src/corelib/serialization/qtextstream.h
@@ -41,10 +41,9 @@
 #define QTEXTSTREAM_H
 
 #include <QtCore/qiodevicebase.h>
-#include <QtCore/qstring.h>
 #include <QtCore/qchar.h>
 #include <QtCore/qscopedpointer.h>
-#include <QtCore/qstringconverter.h>
+#include <QtCore/qstringconverter_base.h>
 
 #include <stdio.h>
 
@@ -56,6 +55,7 @@ QT_BEGIN_NAMESPACE
 
 class QIODevice;
 class QLocale;
+class QString;
 
 class QTextStreamPrivate;
 class Q_CORE_EXPORT QTextStream : public QIODeviceBase
diff --git a/src/corelib/serialization/qtextstream_p.h b/src/corelib/serialization/qtextstream_p.h
index 4a9f54ce1d..445a53703b 100644
--- a/src/corelib/serialization/qtextstream_p.h
+++ b/src/corelib/serialization/qtextstream_p.h
@@ -53,6 +53,7 @@
 //
 
 #include <QtCore/private/qglobal_p.h>
+#include <QtCore/qstringconverter.h>
 #include "qiodevice.h"
 #include "qlocale.h"
 #include "qtextstream.h"
diff --git a/src/corelib/text/qstringconverter.h b/src/corelib/text/qstringconverter.h
index 829b19d568..4d2138f143 100644
--- a/src/corelib/text/qstringconverter.h
+++ b/src/corelib/text/qstringconverter.h
@@ -37,16 +37,22 @@
 **
 ****************************************************************************/
 
+#if 0
+// keep existing syncqt header working after the move of the class
+// into qstringconverter_base
+#pragma qt_class(QStringConverter)
+#pragma qt_class(QStringConverterBase)
+#endif
+
 #ifndef QSTRINGCONVERTER_H
 #define QSTRINGCONVERTER_H
 
+#include <QtCore/qstringconverter_base.h>
 #include <QtCore/qstring.h>
 #if defined(QT_USE_FAST_OPERATOR_PLUS) || defined(QT_USE_QSTRINGBUILDER)
 #include <QtCore/qstringbuilder.h>
 #endif
 
-#include <optional>
-
 QT_BEGIN_NAMESPACE
 
 // work around a compiler bug in GCC 7
@@ -56,138 +62,6 @@ QT_BEGIN_NAMESPACE
 #define QSTRINGCONVERTER_CONSTEXPR constexpr
 #endif
 
-class QStringConverterBase
-{
-public:
-    enum class Flag {
-        Default = 0,
-        Stateless = 0x1,
-        ConvertInvalidToNull = 0x2,
-        WriteBom = 0x4,
-        ConvertInitialBom = 0x8
-    };
-    Q_DECLARE_FLAGS(Flags, Flag)
-
-    struct State {
-        constexpr State(Flags f = Flag::Default)
-            : flags(f), state_data{0, 0, 0, 0} {}
-        ~State() { clear(); }
-        State(State &&other)
-            : flags(other.flags),
-              remainingChars(other.remainingChars),
-              invalidChars(other.invalidChars),
-              d{other.d[0], other.d[1]},
-              clearFn(other.clearFn)
-        { other.clearFn = nullptr; }
-        State &operator=(State &&other)
-        {
-            clear();
-            flags = other.flags;
-            remainingChars = other.remainingChars;
-            invalidChars = other.invalidChars;
-            d[0] = other.d[0];
-            d[1] = other.d[1];
-            clearFn = other.clearFn;
-            other.clearFn = nullptr;
-            return *this;
-        }
-        Q_CORE_EXPORT void clear();
-
-        Flags flags;
-        int internalState = 0;
-        qsizetype remainingChars = 0;
-        qsizetype invalidChars = 0;
-
-        union {
-            uint state_data[4];
-            void *d[2];
-        };
-        using ClearDataFn = void (*)(State *);
-        ClearDataFn clearFn = nullptr;
-    private:
-        Q_DISABLE_COPY(State)
-    };
-};
-Q_DECLARE_OPERATORS_FOR_FLAGS(QStringConverterBase::Flags)
-
-class QStringConverter : public QStringConverterBase
-{
-public:
-
-    enum Encoding {
-        Utf8,
-        Utf16,
-        Utf16LE,
-        Utf16BE,
-        Utf32,
-        Utf32LE,
-        Utf32BE,
-        Latin1,
-        System,
-        LastEncoding = System
-    };
-#ifdef Q_QDOC
-    // document the flags here
-    enum class Flag {
-        Default = 0,
-        Stateless = 0x1,
-        ConvertInvalidToNull = 0x2,
-        WriteBom = 0x4,
-        ConvertInitialBom = 0x8
-    };
-    Q_DECLARE_FLAGS(Flags, Flag)
-#endif
-
-protected:
-
-    struct Interface
-    {
-        using DecoderFn = QChar * (*)(QChar *out, QByteArrayView in, State *state);
-        using LengthFn = qsizetype (*)(qsizetype inLength);
-        using EncoderFn = char * (*)(char *out, QStringView in, State *state);
-        const char *name = nullptr;
-        DecoderFn toUtf16 = nullptr;
-        LengthFn toUtf16Len = nullptr;
-        EncoderFn fromUtf16 = nullptr;
-        LengthFn fromUtf16Len = nullptr;
-    };
-
-    QSTRINGCONVERTER_CONSTEXPR QStringConverter()
-        : iface(nullptr)
-    {}
-    QSTRINGCONVERTER_CONSTEXPR QStringConverter(Encoding encoding, Flags f)
-        : iface(&encodingInterfaces[int(encoding)]), state(f)
-    {}
-    QSTRINGCONVERTER_CONSTEXPR QStringConverter(const Interface *i)
-        : iface(i)
-    {}
-    Q_CORE_EXPORT QStringConverter(const char *name, Flags f);
-
-
-public:
-    bool isValid() const { return iface != nullptr; }
-
-    void resetState()
-    {
-        state.clear();
-    }
-    bool hasError() const { return state.invalidChars != 0; }
-
-    const char *name() const
-    { return isValid() ? iface->name : nullptr; }
-
-    Q_CORE_EXPORT static std::optional<Encoding> encodingForName(const char *name);
-    Q_CORE_EXPORT static const char *nameForEncoding(Encoding e);
-    Q_CORE_EXPORT static std::optional<Encoding> encodingForData(QByteArrayView data, char16_t expectedFirstCharacter = 0);
-    Q_CORE_EXPORT static std::optional<Encoding> encodingForHtml(QByteArrayView data);
-
-protected:
-    const Interface *iface;
-    State state;
-private:
-    Q_CORE_EXPORT static const Interface encodingInterfaces[Encoding::LastEncoding + 1];
-};
-
 class QStringEncoder : public QStringConverter
 {
 protected:
diff --git a/src/corelib/text/qstringconverter_base.h b/src/corelib/text/qstringconverter_base.h
new file mode 100644
index 0000000000..ac147892ee
--- /dev/null
+++ b/src/corelib/text/qstringconverter_base.h
@@ -0,0 +1,194 @@
+/****************************************************************************
+**
+** Copyright (C) 2022 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QSTRINGCONVERTER_BASE_H
+#define QSTRINGCONVERTER_BASE_H
+
+#if 0
+// QStringConverter(Base) class are handled in qstringconverter
+#pragma qt_sync_stop_processing
+#endif
+
+#include <optional>
+
+#include <QtCore/qglobal.h> // QT_{BEGIN,END}_NAMESPACE
+#include <QtCore/qflags.h> // Q_DECLARE_FLAGS
+
+QT_BEGIN_NAMESPACE
+
+class QByteArrayView;
+class QChar;
+class QByteArrayView;
+class QStringView;
+
+class QStringConverterBase
+{
+public:
+    enum class Flag {
+        Default = 0,
+        Stateless = 0x1,
+        ConvertInvalidToNull = 0x2,
+        WriteBom = 0x4,
+        ConvertInitialBom = 0x8
+    };
+    Q_DECLARE_FLAGS(Flags, Flag)
+
+    struct State {
+        constexpr State(Flags f = Flag::Default)
+            : flags(f), state_data{0, 0, 0, 0} {}
+        ~State() { clear(); }
+        State(State &&other)
+            : flags(other.flags),
+              remainingChars(other.remainingChars),
+              invalidChars(other.invalidChars),
+              d{other.d[0], other.d[1]},
+              clearFn(other.clearFn)
+        { other.clearFn = nullptr; }
+        State &operator=(State &&other)
+        {
+            clear();
+            flags = other.flags;
+            remainingChars = other.remainingChars;
+            invalidChars = other.invalidChars;
+            d[0] = other.d[0];
+            d[1] = other.d[1];
+            clearFn = other.clearFn;
+            other.clearFn = nullptr;
+            return *this;
+        }
+        Q_CORE_EXPORT void clear();
+
+        Flags flags;
+        int internalState = 0;
+        qsizetype remainingChars = 0;
+        qsizetype invalidChars = 0;
+
+        union {
+            uint state_data[4];
+            void *d[2];
+        };
+        using ClearDataFn = void (*)(State *);
+        ClearDataFn clearFn = nullptr;
+    private:
+        Q_DISABLE_COPY(State)
+    };
+};
+Q_DECLARE_OPERATORS_FOR_FLAGS(QStringConverterBase::Flags)
+
+class QStringConverter : public QStringConverterBase
+{
+public:
+
+    enum Encoding {
+        Utf8,
+        Utf16,
+        Utf16LE,
+        Utf16BE,
+        Utf32,
+        Utf32LE,
+        Utf32BE,
+        Latin1,
+        System,
+        LastEncoding = System
+    };
+#ifdef Q_QDOC
+    // document the flags here
+    enum class Flag {
+        Default = 0,
+        Stateless = 0x1,
+        ConvertInvalidToNull = 0x2,
+        WriteBom = 0x4,
+        ConvertInitialBom = 0x8
+    };
+    Q_DECLARE_FLAGS(Flags, Flag)
+#endif
+
+protected:
+
+    struct Interface
+    {
+        using DecoderFn = QChar * (*)(QChar *out, QByteArrayView in, State *state);
+        using LengthFn = qsizetype (*)(qsizetype inLength);
+        using EncoderFn = char * (*)(char *out, QStringView in, State *state);
+        const char *name = nullptr;
+        DecoderFn toUtf16 = nullptr;
+        LengthFn toUtf16Len = nullptr;
+        EncoderFn fromUtf16 = nullptr;
+        LengthFn fromUtf16Len = nullptr;
+    };
+
+    constexpr QStringConverter()
+        : iface(nullptr)
+    {}
+    constexpr QStringConverter(Encoding encoding, Flags f)
+        : iface(&encodingInterfaces[int(encoding)]), state(f)
+    {}
+    constexpr QStringConverter(const Interface *i)
+        : iface(i)
+    {}
+    Q_CORE_EXPORT QStringConverter(const char *name, Flags f);
+
+
+public:
+    bool isValid() const { return iface != nullptr; }
+
+    void resetState()
+    {
+        state.clear();
+    }
+    bool hasError() const { return state.invalidChars != 0; }
+
+    const char *name() const
+    { return isValid() ? iface->name : nullptr; }
+
+    Q_CORE_EXPORT static std::optional<Encoding> encodingForName(const char *name);
+    Q_CORE_EXPORT static const char *nameForEncoding(Encoding e);
+    Q_CORE_EXPORT static std::optional<Encoding> encodingForData(QByteArrayView data, char16_t expectedFirstCharacter = 0);
+    Q_CORE_EXPORT static std::optional<Encoding> encodingForHtml(QByteArrayView data);
+
+protected:
+    const Interface *iface;
+    State state;
+private:
+    Q_CORE_EXPORT static const Interface encodingInterfaces[Encoding::LastEncoding + 1];
+};
+
+QT_END_NAMESPACE
+
+#endif
diff --git a/src/network/socket/qlocalsocket_unix.cpp b/src/network/socket/qlocalsocket_unix.cpp
index 21f4f92d15..b31d27a5aa 100644
--- a/src/network/socket/qlocalsocket_unix.cpp
+++ b/src/network/socket/qlocalsocket_unix.cpp
@@ -51,6 +51,7 @@
 #include <qdir.h>
 #include <qdebug.h>
 #include <qelapsedtimer.h>
+#include <qstringconverter.h>
 
 #ifdef Q_OS_VXWORKS
 #  include <selectLib.h>
diff --git a/src/widgets/widgets/qtextbrowser.cpp b/src/widgets/widgets/qtextbrowser.cpp
index 13c21146eb..9ab1635e1d 100644
--- a/src/widgets/widgets/qtextbrowser.cpp
+++ b/src/widgets/widgets/qtextbrowser.cpp
@@ -54,6 +54,7 @@
 #endif
 #include <qtextobject.h>
 #include <qdesktopservices.h>
+#include <qstringconverter.h>
 
 QT_BEGIN_NAMESPACE