13 files changed, 217 insertions, 26 deletions
diff --git a/src/android/jar/build.gradle b/src/android/jar/build.gradle
index 74ecff6b75f..54512f6f4b3 100644
--- a/src/android/jar/build.gradle
+++ b/src/android/jar/build.gradle
@@ -23,7 +23,7 @@ repositories {
 }
 
 android {
-    compileSdk 35
+    compileSdk 36
     namespace = "org.qtproject.qt.android"
 
     defaultConfig {
diff --git a/src/corelib/Qt6AndroidGradleHelpers.cmake b/src/corelib/Qt6AndroidGradleHelpers.cmake
index f71bac4e08a..fc8e009b9da 100644
--- a/src/corelib/Qt6AndroidGradleHelpers.cmake
+++ b/src/corelib/Qt6AndroidGradleHelpers.cmake
@@ -193,7 +193,7 @@ function(_qt_internal_android_generate_target_build_gradle target)
         QT_ANDROID_MIN_SDK_VERSION "28")
 
     _qt_internal_android_get_gradle_property(target_sdk_version ${target}
-        QT_ANDROID_TARGET_SDK_VERSION "34")
+        QT_ANDROID_TARGET_SDK_VERSION "36")
 
     set(target_abis "$<TARGET_PROPERTY:${target},_qt_android_abis>")
     set(target_abi_list "$<JOIN:${target_abis};${CMAKE_ANDROID_ARCH_ABI},'$<COMMA> '>")
diff --git a/src/corelib/doc/images/modelindex-no-parent.svg b/src/corelib/doc/images/modelindex-no-parent.svg
new file mode 100644
index 00000000000..4ce4b86b1f2
--- /dev/null
+++ b/src/corelib/doc/images/modelindex-no-parent.svg
@@ -0,0 +1,99 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   width="300"
+   height="160"
+   version="1.1"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+
+<style>
+  svg .line-style { stroke: black; fill: none }
+  svg .fill-style { stroke: black; fill: #c0c0c0 }
+  svg .text-style { font: 12px arial; fill: black }
+  svg .italic-style { font: 12px arial; fill: black; font-style: italic }
+  svg .bold-style { font: 12px arial; fill: black; font-weight: bold }
+
+  svg.dark .line-style { stroke: #f2f2f2; fill: none }
+  svg.dark .fill-style { stroke: #f2f2f2; fill: #606060 }
+  svg.dark .text-style { font: 12px arial; fill: #f2f2f2 }
+  svg.dark .italic-style { font: 12px arial; fill: #f2f2f2; font-style: italic }
+  svg.dark .bold-style { font: 12px arial; fill: #f2f2f2; font-weight: bold }
+
+  [data-theme="dark"] svg .line-style { stroke: #f2f2f2; fill: none }
+  [data-theme="dark"] svg .fill-style { stroke: #f2f2f2; fill: #606060 }
+  [data-theme="dark"] svg .text-style { font: 12px arial; fill: #f2f2f2 }
+  [data-theme="dark"] svg .italic-style { font: 12px arial; fill: #f2f2f2; font-style: italic }
+  [data-theme="dark"] svg .bold-style { font: 12px arial; fill: #f2f2f2; font-weight: bold }
+
+  [data-theme="light"] svg .line-style { stroke: black; fill: none }
+  [data-theme="light"] svg .fill-style { stroke: black; fill: #c0c0c0 }
+  [data-theme="light"] svg .text-style { font: 12px arial; fill: black }
+  [data-theme="light"] svg .italic-style { font: 12px arial; fill: black; font-style: italic }
+  [data-theme="light"] svg .bold-style { font: 12px arial; fill: black; font-weight: bold }
+</style>
+
+<text x="25" y="49" font-family="arial" font-size="12px"
+      class="text-style">0</text>
+<text x="25" y="79" font-family="arial" font-size="12px"
+      class="text-style">1</text>
+<text x="25" y="109" font-family="arial" font-size="12px"
+      class="text-style">2</text>
+<g transform="translate(30,139)">
+<text x="0" y="0" font-family="arial" font-size="12px"
+      class="text-style" transform="rotate(270)">...</text>
+</g>
+
+<path d="m 40.5,30.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" />
+<path d="m 70.5,30.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" />
+<path d="m 100.5,30.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" />
+<path d="m 130.5,30.5 h 30 v 30" stroke="black" fill="none"
+      class="line-style" stroke-dasharray="3, 3" />
+<path d="m 40.5,60.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" />
+<path d="m 70.5,60.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" />
+<path d="m 100.5,60.5 h 30 v 30 h -30 z" stroke="black" fill="#c0c0c0"
+      class="fill-style" />
+<path d="m 130.5,60.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" stroke-dasharray="3, 3" />
+<path d="m 40.5,90.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" />
+<path d="m 70.5,90.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" />
+<path d="m 100.5,90.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" />
+<path d="m 70.5,120.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" stroke-dasharray="3, 3" />
+<path d="m 40.5,120.5 v 30 h 30" stroke="black" fill="none"
+      class="line-style" stroke-dasharray="3, 3" />
+<path d="m 100.5,150.5 h 30" stroke="black"
+      class="line-style" stroke-dasharray="3, 3" />
+<path d="m 130.5,120.5 h 30 v 30 h -30 z" stroke="black" fill="none"
+      class="line-style" stroke-dasharray="3, 3" />
+<path d="m 160.5,90.5 v 30" stroke="black"
+      class="line-style" stroke-dasharray="3, 3" />
+
+<text x="50" y="20" font-family="arial" font-size="12px"
+      class="text-style">0</text>
+<text x="80" y="20" font-family="arial" font-size="12px"
+      class="text-style">1</text>
+<text x="110" y="20" font-family="arial" font-size="12px"
+      class="text-style">2</text>
+<text x="140" y="20" font-family="arial" font-size="12px"
+      class="text-style">...</text>
+
+<text x="190" y="55" font-family="arial" font-size="12px" font-weight="bold"
+      class="bold-style">Model index</text>
+<rect x="185.5" y="60.5" width="77" height="37" stroke="black" fill="none"
+      class="line-style" />
+<text x="190" y="75" font-family="arial" font-size="12px"
+      class="text-style">row = 1</text>
+<text x="190" y="92" font-family="arial" font-size="12px"
+      class="text-style">column = 2</text>
+
+<path d="m 185.5,85.5 c -35,0 -35,-10 -70,-10" stroke="black" fill="none"
+      stroke-dasharray="2, 2" class="line-style" />
+</svg>
diff --git a/src/corelib/doc/src/cmake/cmake-properties.qdoc b/src/corelib/doc/src/cmake/cmake-properties.qdoc
index c7b1a27a4b4..310debf7edc 100644
--- a/src/corelib/doc/src/cmake/cmake-properties.qdoc
+++ b/src/corelib/doc/src/cmake/cmake-properties.qdoc
@@ -239,7 +239,7 @@ precedence over this CMake property.
 
 \badcode
 set_target_properties(${target} PROPERTIES
-    QT_ANDROID_COMPILE_SDK_VERSION 35
+    QT_ANDROID_COMPILE_SDK_VERSION 36
 )
 \endcode
 
@@ -247,7 +247,7 @@ The following format also works:
 
 \badcode
 set_target_properties(${target} PROPERTIES
- QT_ANDROID_COMPILE_SDK_VERSION "android-35"
+ QT_ANDROID_COMPILE_SDK_VERSION "android-36"
 )
 \endcode
 
diff --git a/src/corelib/itemmodels/qabstractitemmodel.cpp b/src/corelib/itemmodels/qabstractitemmodel.cpp
index 58a057009ff..8b0a05ee6ed 100644
--- a/src/corelib/itemmodels/qabstractitemmodel.cpp
+++ b/src/corelib/itemmodels/qabstractitemmodel.cpp
@@ -1390,7 +1390,7 @@ void QAbstractItemModel::resetInternalData()
     simple table of rows and columns. Each item has a unique index specified by
     a QModelIndex.
 
-    \image modelindex-no-parent.png {Screenshot showing a 3x3 grid with numbered
+    \image modelindex-no-parent.svg {Diagram showing a 3x3 grid with numbered
            rows and columns that shows the cell at row 1, column 2 highlighted.}
 
     Every item of data that can be accessed via a model has an associated model
diff --git a/src/network/android/jar/build.gradle b/src/network/android/jar/build.gradle
index f1f470b6635..580e15b92f6 100644
--- a/src/network/android/jar/build.gradle
+++ b/src/network/android/jar/build.gradle
@@ -23,7 +23,7 @@ repositories {
 }
 
 android {
-    compileSdk 35
+    compileSdk 36
 
     defaultConfig {
         minSdkVersion 28
diff --git a/src/plugins/networkinformation/android/jar/build.gradle b/src/plugins/networkinformation/android/jar/build.gradle
index f1f470b6635..580e15b92f6 100644
--- a/src/plugins/networkinformation/android/jar/build.gradle
+++ b/src/plugins/networkinformation/android/jar/build.gradle
@@ -23,7 +23,7 @@ repositories {
 }
 
 android {
-    compileSdk 35
+    compileSdk 36
 
     defaultConfig {
         minSdkVersion 28
diff --git a/src/plugins/platforms/cocoa/qnsview.mm b/src/plugins/platforms/cocoa/qnsview.mm
index a6d96df0fbb..b00e6375e1a 100644
--- a/src/plugins/platforms/cocoa/qnsview.mm
+++ b/src/plugins/platforms/cocoa/qnsview.mm
@@ -269,6 +269,23 @@ QT_NAMESPACE_ALIAS_OBJC_CLASS(QNSViewMenuHelper);
     qCDebug(lcQpaWindow) << "Done moving" << self << "to" << self.window;
 }
 
+// QWindow::setParent() promises that the child window will be clipped
+// to its parent, which we rely on in e.g. Qt Widgets when a native window
+// is added to a scroll area. We try to be smart and only enable clipping
+// if we have potential child QWindows that rely on this behavior.
+// FIXME: Be even smarter, and only consider QWindow based subviews,
+// in a way that also includes foreign windows.
+
+- (void)didAddSubview:(NSView *)subview
+{
+    self.clipsToBounds = YES;
+}
+
+- (void)willRemoveSubview:(NSView *)subview
+{
+    self.clipsToBounds = self.subviews.count > 1;
+}
+
 // ----------------------------------------------------------------------------
 
 - (QWindow *)topLevelWindow
diff --git a/src/tools/androiddeployqt/main.cpp b/src/tools/androiddeployqt/main.cpp
index 7f24df7eac2..c4e7101b372 100644
--- a/src/tools/androiddeployqt/main.cpp
+++ b/src/tools/androiddeployqt/main.cpp
@@ -173,7 +173,7 @@ struct Options
     QString versionName;
     QString versionCode;
     QByteArray minSdkVersion{"28"};
-    QByteArray targetSdkVersion{"35"};
+    QByteArray targetSdkVersion{"36"};
 
     // lib c++ path
     QString stdCppPath;
diff --git a/src/tools/bootstrap/CMakeLists.txt b/src/tools/bootstrap/CMakeLists.txt
index f9161fa6404..c12475d69af 100644
--- a/src/tools/bootstrap/CMakeLists.txt
+++ b/src/tools/bootstrap/CMakeLists.txt
@@ -221,6 +221,8 @@ qt_internal_apply_gc_binaries(Bootstrap PUBLIC)
 set_target_properties(Bootstrap PROPERTIES AUTOMOC OFF AUTOUIC OFF AUTORCC OFF)
 qt_internal_add_target_aliases(Bootstrap)
 qt_internal_add_target_optimized_flags_for_debug_config_in_current_scope(Bootstrap)
+qt_internal_enable_optimized_tools_lto(Bootstrap)
+qt_internal_workaround_static_lib_gcc_lto_issue(Bootstrap)
 
 qt_set_msvc_cplusplus_options(Bootstrap PUBLIC)
 qt_set_common_target_properties(Bootstrap)
diff --git a/src/tools/rcc/rcc.cpp b/src/tools/rcc/rcc.cpp
index 40bfa9c2863..6a6027d44f2 100644
--- a/src/tools/rcc/rcc.cpp
+++ b/src/tools/rcc/rcc.cpp
@@ -1,10 +1,12 @@
 // Copyright (C) 2018 The Qt Company Ltd.
 // Copyright (C) 2018 Intel Corporation.
+// Copyright (C) 2024 Christoph Cullmann <christoph@cullmann.io>
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
 
 #include "rcc.h"
 
 #include <qbytearray.h>
+#include <qcryptographichash.h>
 #include <qdatetime.h>
 #include <qdebug.h>
 #include <qdir.h>
@@ -90,8 +92,28 @@ public:
 
     QString resourceName() const;
 
+    struct DeduplicationKey {
+        RCCResourceLibrary::CompressionAlgorithm compressAlgo;
+        int compressLevel;
+        int compressThreshold;
+        QByteArray hash;
+
+        bool operator==(const DeduplicationKey &other) const
+        {
+            return compressAlgo == other.compressAlgo &&
+                   compressLevel == other.compressLevel &&
+                   compressThreshold == other.compressThreshold &&
+                   hash == other.hash;
+        }
+    };
+
+    typedef QMultiHash<DeduplicationKey, RCCFileInfo*> DeduplicationMultiHash;
+
 public:
-    qint64 writeDataBlob(RCCResourceLibrary &lib, qint64 offset, QString *errorMessage);
+    qint64 writeDataBlob(RCCResourceLibrary &lib,
+                         qint64 offset,
+                         DeduplicationMultiHash &dedupByContent,
+                         QString *errorMessage);
     qint64 writeDataName(RCCResourceLibrary &, qint64 offset);
     void writeDataInfo(RCCResourceLibrary &lib);
 
@@ -114,6 +136,11 @@ public:
     qint64 m_childOffset = 0;
 };
 
+static size_t qHash(const RCCFileInfo::DeduplicationKey &key, size_t seed) noexcept
+{
+    return qHashMulti(seed, key.compressAlgo, key.compressLevel, key.compressThreshold, key.hash);
+}
+
 RCCFileInfo::RCCFileInfo(const QString &name, const QFileInfo &fileInfo, QLocale::Language language,
                          QLocale::Territory territory, uint flags,
                          RCCResourceLibrary::CompressionAlgorithm compressAlgo, int compressLevel,
@@ -217,8 +244,10 @@ void RCCFileInfo::writeDataInfo(RCCResourceLibrary &lib)
     }
 }
 
-qint64 RCCFileInfo::writeDataBlob(RCCResourceLibrary &lib, qint64 offset,
-    QString *errorMessage)
+qint64 RCCFileInfo::writeDataBlob(RCCResourceLibrary &lib,
+                                  qint64 offset,
+                                  DeduplicationMultiHash &dedupByContent,
+                                  QString *errorMessage)
 {
     const bool text = lib.m_format == RCCResourceLibrary::C_Code;
     const bool pass1 = lib.m_format == RCCResourceLibrary::Pass1;
@@ -230,24 +259,58 @@ qint64 RCCFileInfo::writeDataBlob(RCCResourceLibrary &lib, qint64 offset,
     m_dataOffset = offset;
     QByteArray data;
 
+    // determine compession algorithm & level early as used in de-duplication keys
+    // this avoid corruption for the two pass variants (QTBUG-137546)
+#if QT_CONFIG(zstd)
+    if (m_compressAlgo == RCCResourceLibrary::CompressionAlgorithm::Best && !m_noZstd) {
+        m_compressAlgo = RCCResourceLibrary::CompressionAlgorithm::Zstd;
+        m_compressLevel = 19;   // not ZSTD_maxCLevel(), as 20+ are experimental
+    }
+#endif
+#ifndef QT_NO_COMPRESS
+    if (m_compressAlgo == RCCResourceLibrary::CompressionAlgorithm::Best) {
+        m_compressAlgo = RCCResourceLibrary::CompressionAlgorithm::Zlib;
+        m_compressLevel = 9;
+    }
+#endif
+
     if (!m_isEmpty) {
-        //find the data to be written
-        QFile file(m_fileInfo.absoluteFilePath());
+        // find the data to be written
+        const QString absoluteFilePath = m_fileInfo.absoluteFilePath();
+        QFile file(absoluteFilePath);
         if (!file.open(QFile::ReadOnly)) {
-            *errorMessage = msgOpenReadFailed(m_fileInfo.absoluteFilePath(), file.errorString());
+            *errorMessage = msgOpenReadFailed(absoluteFilePath, file.errorString());
             return 0;
         }
-
         data = file.readAll();
+
+        // de-duplicate the same file content, we can re-use already written data
+        // we only do that if we have the same compression settings
+        const QByteArray hash = QCryptographicHash::hash(data, QCryptographicHash::Sha256);
+        const DeduplicationKey key{m_compressAlgo, m_compressLevel, m_compressThreshold, hash};
+        const QList<RCCFileInfo *> potentialCandidates = dedupByContent.values(key);
+        for (const RCCFileInfo *candidate : potentialCandidates) {
+            // check real content, we can have collisions
+            QFile candidateFile(candidate->m_fileInfo.absoluteFilePath());
+            if (!candidateFile.open(QFile::ReadOnly)) {
+                *errorMessage = msgOpenReadFailed(candidate->m_fileInfo.absoluteFilePath(),
+                                                  candidateFile.errorString());
+                return 0;
+            }
+            if (data != candidateFile.readAll())
+                continue;
+            // just remember the offset & flags with final compression state
+            // of the already written data and be done
+            m_dataOffset = candidate->m_dataOffset;
+            m_flags = candidate->m_flags;
+            return offset;
+        }
+        dedupByContent.insert(key, this);
     }
 
     // Check if compression is useful for this file
     if (data.size() != 0) {
 #if QT_CONFIG(zstd)
-        if (m_compressAlgo == RCCResourceLibrary::CompressionAlgorithm::Best && !m_noZstd) {
-            m_compressAlgo = RCCResourceLibrary::CompressionAlgorithm::Zstd;
-            m_compressLevel = 19;   // not ZSTD_maxCLevel(), as 20+ are experimental
-        }
         if (m_compressAlgo == RCCResourceLibrary::CompressionAlgorithm::Zstd && !m_noZstd) {
             if (lib.m_zstdCCtx == nullptr)
                 lib.m_zstdCCtx = ZSTD_createCCtx();
@@ -292,10 +355,6 @@ qint64 RCCFileInfo::writeDataBlob(RCCResourceLibrary &lib, qint64 offset,
         }
 #endif
 #ifndef QT_NO_COMPRESS
-        if (m_compressAlgo == RCCResourceLibrary::CompressionAlgorithm::Best) {
-            m_compressAlgo = RCCResourceLibrary::CompressionAlgorithm::Zlib;
-            m_compressLevel = 9;
-        }
         if (m_compressAlgo == RCCResourceLibrary::CompressionAlgorithm::Zlib) {
             QByteArray compressed =
                     qCompress(reinterpret_cast<uchar *>(data.data()), data.size(), m_compressLevel);
@@ -1168,6 +1227,7 @@ bool RCCResourceLibrary::writeDataBlobs()
     QStack<RCCFileInfo*> pending;
     pending.push(m_root);
     qint64 offset = 0;
+    RCCFileInfo::DeduplicationMultiHash dedupByContent;
     QString errorMessage;
     while (!pending.isEmpty()) {
         RCCFileInfo *file = pending.pop();
@@ -1176,7 +1236,8 @@ bool RCCResourceLibrary::writeDataBlobs()
             if (child->m_flags & RCCFileInfo::Directory)
                 pending.push(child);
             else {
-                offset = child->writeDataBlob(*this, offset, &errorMessage);
+                offset = child->writeDataBlob(*this, offset,
+                                              dedupByContent, &errorMessage);
                 if (offset == 0) {
                     m_errorDevice->write(errorMessage.toUtf8());
                     return false;
diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index d2b0fb724ac..a735696adcb 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -3741,6 +3741,14 @@ void QApplicationPrivate::cleanupMultitouch_sys()
 {
 }
 
+/*! \internal
+    Check the target widgets of the active touchpoints of the given \a device,
+    and choose the widget that is closest to any of the points. This widget
+    will then get all the touchpoints, even if it would not otherwise be the
+    target for some of them.
+
+    \sa translateRawTouchEvent()
+*/
 QWidget *QApplicationPrivate::findClosestTouchPointTarget(const QPointingDevice *device, const QEventPoint &touchPoint)
 {
     const QPointF globalPos = touchPoint.globalPosition();
@@ -3754,7 +3762,10 @@ QWidget *QApplicationPrivate::findClosestTouchPointTarget(const QPointingDevice
             qreal dx = globalPos.x() - pt.globalPosition().x();
             qreal dy = globalPos.y() - pt.globalPosition().y();
             qreal distance = dx * dx + dy * dy;
-            if (closestTouchPointId == -1 || distance < closestDistance) {
+            // closestTouchPointId is -1 at the beginning.
+            // closestTouchPointId may be 0 if
+            // a synth-mouse eventPoint was found in activePoints: that's not relevant here.
+            if (closestTouchPointId <= 0 || distance < closestDistance) {
                 closestTouchPointId = pt.id();
                 closestDistance = distance;
                 closestTarget = QMutableEventPoint::target(pt);
diff --git a/src/widgets/styles/qfusionstyle_p_p.h b/src/widgets/styles/qfusionstyle_p_p.h
index dcb79f9e93c..821be49b2fa 100644
--- a/src/widgets/styles/qfusionstyle_p_p.h
+++ b/src/widgets/styles/qfusionstyle_p_p.h
@@ -94,7 +94,8 @@ public:
         QColor buttonColor = pal.button().color();
         int val = qGray(buttonColor.rgb());
         buttonColor = buttonColor.lighter(100 + qMax(1, (180 - val)/6));
-        buttonColor.setHsv(buttonColor.hue(), buttonColor.saturation() * 0.75, buttonColor.value());
+        buttonColor.setHsv(buttonColor.hue(), buttonColor.saturation() * 0.75,
+                           buttonColor.value(), buttonColor.alpha());
         return buttonColor;
     }