Do not duplicate JsonFormat enum

The enum already exists in QJsonDocument, so there is no reason to
introduce a new one in QJsonValue.

Instead, use the fact that we only need to forward-declare QJsonValue
in QJsonDocument's header, include the latter into qjsonvalue.h, and
use a type alias.

For Qt 7, pre-program moving of the enum into QJsonValue and using
an alias in QJsonDocument.

Amends ac73079dee5f0260528a5c217a82cb0beafb0a56.

Found in Qt 6.9 API review.

[ChangeLog][QtCore][Potentially Source-Incompatible Changes] The
QJsonDocument header no longer includes QJsonValue.
The backward-compatible fix is to include all needed headers
explicitly and to not rely on the transitive includes.

Change-Id: I7c5219a239149e4a87d4780c4277d111983ad0f4
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 3cb87d891bb040f73fb68b6c5e7e82518f603c59)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/serialization/qjsondocument.cpp

@@ -216,6 +216,7 @@ QVariant QJsonDocument::toVariant() const
 #endif // !QT_NO_VARIANT
 
 /*!
+\if !defined(qt7)
     \enum QJsonDocument::JsonFormat
     \since 5.1
 
@@ -227,6 +228,12 @@ QVariant QJsonDocument::toVariant() const
 
     \value Compact Defines a compact output as follows:
         \snippet code/src_corelib_serialization_qjsondocument.cpp 1
+\else
+    \typealias QJsonDocument::JsonFormat
+    \since 5.1
+
+    Same as \l QJsonValue::JsonFormat.
+\endif
   */
 
 /*!
@@ -243,7 +250,8 @@ QByteArray QJsonDocument::toJson(JsonFormat format) const
         return json;
 
     return QJsonPrivate::Value::fromTrustedCbor(d->value).toJson(
-            format == JsonFormat::Compact ? QJsonValue::Compact : QJsonValue::Indented);
+            format == JsonFormat::Compact ? QJsonValue::JsonFormat::Compact
+                                          : QJsonValue::JsonFormat::Indented);
 }
 #endif
 
@@ -472,7 +480,8 @@ QDebug operator<<(QDebug dbg, const QJsonDocument &o)
         dbg << "QJsonDocument()";
         return dbg;
     }
-    QByteArray json = QJsonPrivate::Value::fromTrustedCbor(o.d->value).toJson(QJsonValue::Compact);
+    QByteArray json =
+        QJsonPrivate::Value::fromTrustedCbor(o.d->value).toJson(QJsonValue::JsonFormat::Compact);
     dbg.nospace() << "QJsonDocument("
                   << json.constData() // print as utf-8 string without extra quotation marks
                   << ')';

src/corelib/serialization/qjsondocument.h

@@ -6,8 +6,12 @@
 
 #include <QtCore/qcompare.h>
 #include <QtCore/qjsonparseerror.h>
+#if (QT_VERSION >= QT_VERSION_CHECK(7, 0, 0)) || defined(QT_BOOTSTRAPPED)
 #include <QtCore/qjsonvalue.h>
+#endif
+#include <QtCore/qlatin1stringview.h>
 #include <QtCore/qscopedpointer.h>
+#include <QtCore/qstringview.h>
 
 #include <memory>
 
@@ -15,6 +19,9 @@ QT_BEGIN_NAMESPACE
 
 class QDebug;
 class QCborValue;
+class QJsonArray;
+class QJsonObject;
+class QJsonValue;
 
 namespace QJsonPrivate { class Parser; }
 
@@ -49,15 +56,26 @@ public:
     static QJsonDocument fromVariant(const QVariant &variant);
     QVariant toVariant() const;
 
+#if (QT_VERSION < QT_VERSION_CHECK(7, 0, 0)) && !defined(QT_BOOTSTRAPPED)
     enum JsonFormat {
         Indented,
         Compact
     };
+#else
+    using JsonFormat = QJsonValue::JsonFormat;
+#  ifdef __cpp_using_enum
+    using enum QJsonValue::JsonFormat;
+#  else
+    // keep in sync with qjsonvalue.h
+    static constexpr auto Indented = JsonFormat::Indented;
+    static constexpr auto Compact = JsonFormat::Compact;
+#  endif
+#endif
 
     static QJsonDocument fromJson(const QByteArray &json, QJsonParseError *error = nullptr);
 
 #if !defined(QT_JSON_READONLY) || defined(Q_QDOC)
-    QByteArray toJson(JsonFormat format = Indented) const;
+    QByteArray toJson(JsonFormat format = JsonFormat::Indented) const;
 #endif
 
     bool isEmpty() const;

src/corelib/serialization/qjsonvalue.cpp

@@ -616,6 +616,7 @@ QJsonValue QJsonValue::fromJson(QByteArrayView json, QJsonParseError *error)
 }
 
 /*!
+\if defined(qt7)
     \enum QJsonValue::JsonFormat
     \since 6.9
 
@@ -627,7 +628,13 @@ QJsonValue QJsonValue::fromJson(QByteArrayView json, QJsonParseError *error)
 
     \value Compact Defines a compact output as follows:
         \snippet code/src_corelib_serialization_qjsondocument.cpp 1
-  */
+\else
+    \typealias QJsonValue::JsonFormat
+    \since 6.9
+
+    Same as \l QJsonDocument::JsonFormat.
+\endif
+*/
 
 /*!
     \since 6.9
@@ -640,7 +647,7 @@ QByteArray QJsonValue::toJson(JsonFormat format) const
 {
     QByteArray json;
 
-    QJsonPrivate::Writer::valueToJson(value, json, 0, (format == Compact));
+    QJsonPrivate::Writer::valueToJson(value, json, 0, (format == JsonFormat::Compact));
 
     return json;
 }

src/corelib/serialization/qjsonvalue.h

@@ -7,6 +7,9 @@
 #include <QtCore/qcborvalue.h>
 #include <QtCore/qcompare.h>
 #include <QtCore/qglobal.h>
+#if (QT_VERSION < QT_VERSION_CHECK(7, 0, 0)) && !defined(QT_BOOTSTRAPPED)
+#include <QtCore/qjsondocument.h>
+#endif
 #include <QtCore/qjsonparseerror.h>
 #include <QtCore/qstring.h>
 #include <QtCore/qshareddata.h>
@@ -35,10 +38,14 @@ public:
         Undefined = 0x80
     };
 
-    enum JsonFormat {
+#if (QT_VERSION < QT_VERSION_CHECK(7, 0, 0)) && !defined(QT_BOOTSTRAPPED)
+    using JsonFormat = QJsonDocument::JsonFormat;
+#else
+    enum class JsonFormat {
         Indented,
         Compact,
     };
+#endif
 
     QJsonValue(Type = Null);
     QJsonValue(bool b);

tests/auto/corelib/serialization/json/tst_qtjson.cpp

@@ -1989,7 +1989,7 @@ void tst_QtJson::toJson()
         array.append(QLatin1String("\\\a\n\r\b\tabcABC\""));
         object.insert("Array", array);
 
-        QByteArray json = QJsonValue(object).toJson(QJsonValue::Compact);
+        QByteArray json = QJsonValue(object).toJson(QJsonValue::JsonFormat::Compact);
         QByteArray expected =
                 "{\"Array\":[true,999,\"string\",null,\"\\\\\\u0007\\n\\r\\b\\tabcABC\\\"\"],\"\\\\Key\\n\":\"Value\",\"null\":null}";
         QCOMPARE(json, expected);
@@ -2004,7 +2004,7 @@ void tst_QtJson::toJson()
         json = doc.toJson(QJsonDocument::Compact);
         expected = "[true,999,\"string\",null,\"\\\\\\u0007\\n\\r\\b\\tabcABC\\\"\"]";
         QCOMPARE(json, expected);
-        QCOMPARE(QJsonValue(array).toJson(QJsonValue::Compact), expected);
+        QCOMPARE(QJsonValue(array).toJson(QJsonValue::JsonFormat::Compact), expected);
     }
 }
 
@@ -2155,7 +2155,7 @@ void tst_QtJson::toJsonTopLevel()
     QFETCH(QByteArray, result);
 
     QCOMPARE(value.toJson(), result);
-    QCOMPARE(value.toJson(QJsonValue::Compact), result);
+    QCOMPARE(value.toJson(QJsonValue::JsonFormat::Compact), result);
 }
 
 void tst_QtJson::fromJson()
@@ -3213,7 +3213,7 @@ void tst_QtJson::makeEscapes()
     QByteArray resultStr = result;
 
     QJsonArray array = { input };
-    QByteArray json = QJsonValue(array).toJson(QJsonValue::Compact);
+    QByteArray json = QJsonValue(array).toJson(QJsonValue::JsonFormat::Compact);
     QCOMPARE(QJsonDocument(array).toJson(QJsonDocument::Compact), json);
     QByteArray jsonStr = QJsonValue(input).toJson();