chromium-114-add_qt6_linuxui_backend.patch

commit 75f4b48eb71d4872ba3ac6c9fc3662a60eb4175d
Author: Tom Anderson <thomasanderson@chromium.org>
Date:   Thu Apr 27 02:21:34 2023 +0000

    Add QT6 LinuxUi backend
    
    - Enable QT6 by default on KDE6
    - If QT6 load fails, fallback to QT5 (and vice versa)
    - Add use_qt6 build flag for packager control
    - Add --qt-version runtime flag for user control
    
    R=thestig
    
    Change-Id: Ib1d9f6183663ecf7b9ddfe9d7f3e3442e534ccda
    Fixed: 1434754
    Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4475369
    Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
    Reviewed-by: Lei Zhang <thestig@chromium.org>
    Cr-Commit-Position: refs/heads/main@{#1136295}

diff --git a/chrome/installer/linux/BUILD.gn b/chrome/installer/linux/BUILD.gn
index 5639b9ffc996e..3bacd3398d4a2 100644
--- a/chrome/installer/linux/BUILD.gn
+++ b/chrome/installer/linux/BUILD.gn
@@ -109,6 +109,9 @@ if (use_qt) {
   # to prevent a hard dependency on QT for the package.
   packaging_files += [ "$root_out_dir/libqt5_shim.so" ]
 }
+if (use_qt6) {
+  packaging_files += [ "$root_out_dir/libqt6_shim.so" ]
+}
 
 action_foreach("calculate_deb_dependencies") {
   deps = [ ":installer_deps" ]
@@ -249,6 +252,12 @@ if (use_qt) {
     deps = [ "//ui/qt:qt5_shim" ]
   }
 }
+if (use_qt6) {
+  strip_binary("strip_qt6_shim") {
+    binary_input = "$root_out_dir/libqt6_shim.so"
+    deps = [ "//ui/qt:qt6_shim" ]
+  }
+}
 
 # This target builds all "normal" Linux installers.  You must set
 # is_component_build=false before building this target.
@@ -447,6 +456,12 @@ group("installer_deps") {
       "//ui/qt:qt5_shim",
     ]
   }
+  if (use_qt6) {
+    public_deps += [
+      ":strip_qt6_shim",
+      "//ui/qt:qt6_shim",
+    ]
+  }
 }
 
 # Creates .deb and .rpm (RPM for non-ChromeOS only) installer packages.
diff --git a/chrome/installer/linux/common/installer.include b/chrome/installer/linux/common/installer.include
index 8d76f1f280b01..439ef5ccb0f52 100644
--- a/chrome/installer/linux/common/installer.include
+++ b/chrome/installer/linux/common/installer.include
@@ -254,6 +254,11 @@ stage_install_common() {
     strippedfile="${OUTPUTDIR}/${file}.stripped"
     install -m ${SHLIB_PERMS} "${strippedfile}" "${STAGEDIR}/${INSTALLDIR}/${file}"
   fi
+  if [ -f "${OUTPUTDIR}/libqt6_shim.so" ]; then
+    file="libqt6_shim.so"
+    strippedfile="${OUTPUTDIR}/${file}.stripped"
+    install -m ${SHLIB_PERMS} "${strippedfile}" "${STAGEDIR}/${INSTALLDIR}/${file}"
+  fi
 
   # libc++
   if [ -f "${OUTPUTDIR}/lib/libc++.so" ]; then
diff --git a/ui/qt/BUILD.gn b/ui/qt/BUILD.gn
index bbede00daa4d0..6a67961edc2f7 100644
--- a/ui/qt/BUILD.gn
+++ b/ui/qt/BUILD.gn
@@ -11,13 +11,6 @@ assert(use_qt)
 assert(is_linux)
 assert(!is_castos)
 
-pkg_config("qt5_config") {
-  packages = [
-    "Qt5Core",
-    "Qt5Widgets",
-  ]
-}
-
 config("qt_internal_config") {
   if (is_clang) {
     # libstdc++ headers are incompatible with -fcomplete-member-pointers.
@@ -56,40 +49,57 @@ if (!use_sysroot) {
   }
 }
 
-shared_library("qt5_shim") {
-  visibility = [
-    ":qt",
-    "//chrome/installer/linux:*",
-  ]
-
-  # Since qt_shim is a shared library even in non-component builds, it shouldn't
-  # depend on any other targets since that would duplicate code between binaries
-  # leading to increased size and potential issues from duplicated global state.
-  no_default_deps = true
-  assert_no_deps = [
-    "//base",
-    "//buildtools/third_party/libc++",
-  ]
-  deps = [ ":qt_interface" ]
-
-  configs -= [ "//build/config/compiler:runtime_library" ]
-  configs += [
-    ":qt_internal_config",
-    ":qt5_config",
-  ]
+template("qt_shim") {
+  pkg_config("qt" + invoker.qt_version + "_config") {
+    packages = [
+      "Qt" + invoker.qt_version + "Core",
+      "Qt" + invoker.qt_version + "Widgets",
+    ]
+  }
 
-  public = []
-  sources = [
-    "qt_shim.cc",
-    "qt_shim.h",
-  ]
-  if (use_sysroot) {
-    # This file is generated with gen_qt_shim_moc.sh on an amd64 system to
-    # avoid a build-time dependency on `moc` when using the sysroot.
-    sources += [ "qt_shim_moc.cc" ]
-  } else {
-    sources += get_target_outputs(":generate_moc")
-    deps += [ ":generate_moc" ]
+  shared_library(target_name) {
+    visibility = [
+      ":qt",
+      "//chrome/installer/linux:*",
+    ]
+
+    # Since qt_shim is a shared library even in non-component builds, it shouldn't
+    # depend on any other targets since that would duplicate code between binaries
+    # leading to increased size and potential issues from duplicated global state.
+    no_default_deps = true
+    assert_no_deps = [
+      "//base",
+      "//buildtools/third_party/libc++",
+    ]
+    deps = [ ":qt_interface" ]
+
+    configs -= [ "//build/config/compiler:runtime_library" ]
+    configs += [
+      ":qt_internal_config",
+      ":qt" + invoker.qt_version + "_config",
+    ]
+
+    public = []
+    sources = [
+      "qt_shim.cc",
+      "qt_shim.h",
+    ]
+    if (use_sysroot) {
+      # This file is generated with gen_qt_shim_moc.sh on an amd64 system to
+      # avoid a build-time dependency on `moc` when using the sysroot.
+      sources += [ "qt" + invoker.qt_version + "_shim_moc.cc" ]
+    } else {
+      sources += get_target_outputs(":generate_moc")
+      deps += [ ":generate_moc" ]
+    }
+  }
+}
+qt_shim("qt5_shim") {
+  qt_version = "5"
+}
+if (use_qt6) {
+  qt_shim("qt6_shim") {
+    qt_version = "6"
   }
 }
 
@@ -100,6 +110,9 @@ component("qt") {
 
   # qt_shim is in data_deps since we want to load it manually.
   data_deps = [ ":qt5_shim" ]
+  if (use_qt6) {
+    data_deps += [ ":qt6_shim" ]
+  }
   deps = [
     ":qt_interface",
     "//base",
diff --git a/ui/qt/gen_qt_shim_moc.sh b/ui/qt/gen_qt_shim_moc.sh
index 74272d5611dab..9d02c2dfcb12f 100755
--- a/ui/qt/gen_qt_shim_moc.sh
+++ b/ui/qt/gen_qt_shim_moc.sh
@@ -6,11 +6,15 @@
 set -o nounset
 set -o errexit
 
-URL="http://archive.debian.org/debian/pool/main/q/qtbase-opensource-src"
-PACKAGE="qtbase5-dev-tools_5.3.2+dfsg-4+deb8u2_amd64.deb"
-SHA256="7703754f2c230ce6b8b6030b6c1e7e030899aa9f45a415498df04bd5ec061a76"
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+URL5="http://archive.debian.org/debian/pool/main/q/qtbase-opensource-src"
+PACKAGE5="qtbase5-dev-tools_5.3.2+dfsg-4+deb8u2_amd64.deb"
+SHA256_5="7703754f2c230ce6b8b6030b6c1e7e030899aa9f45a415498df04bd5ec061a76"
+
+URL6="http://archive.ubuntu.com/ubuntu/pool/universe/q/qt6-base"
+PACKAGE6="qt6-base-dev-tools_6.2.4+dfsg-2ubuntu1_amd64.deb"
+SHA256_6="8dddfc79e7743185b07c478ca0f96a4ccc13d48ecccc42f44d2578c33c7d9b8b"
 
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 TMP_DIR=$(mktemp -d -p "$SCRIPT_DIR")
 function cleanup {
     rm -rf "$TMP_DIR"
@@ -18,16 +22,22 @@ function cleanup {
 trap cleanup EXIT
 
 cd "$TMP_DIR"
-wget "$URL/$PACKAGE"
-echo "$SHA256  $PACKAGE" | shasum -a 256 -c
-dpkg -x "$PACKAGE" .
-cat > ../qt_shim_moc.cc <<EOF
-// Copyright 2022 The Chromium Authors
+wget "$URL5/$PACKAGE5"
+echo "$SHA256_5  $PACKAGE5" | shasum -a 256 -c
+dpkg -x "$PACKAGE5" .
+wget "$URL6/$PACKAGE6"
+echo "$SHA256_6  $PACKAGE6" | shasum -a 256 -c
+dpkg -x "$PACKAGE6" .
+cat > ../qt5_shim_moc.cc <<EOF
+// Copyright 2023 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 EOF
 cd "$SCRIPT_DIR/../.."
+cp ui/qt/qt5_shim_moc.cc ui/qt/qt6_shim_moc.cc
 "$TMP_DIR/usr/lib/x86_64-linux-gnu/qt5/bin/moc" ui/qt/qt_shim.h \
-    >> ui/qt/qt_shim_moc.cc
-git cl format ui/qt/qt_shim_moc.cc
+    >> ui/qt/qt5_shim_moc.cc
+"$TMP_DIR//usr/lib/qt6/libexec/moc" ui/qt/qt_shim.h \
+    >> ui/qt/qt6_shim_moc.cc
+git cl format ui/qt/qt5_shim_moc.cc ui/qt/qt6_shim_moc.cc
diff --git a/ui/qt/qt.gni b/ui/qt/qt.gni
index 27bb6375880b7..f45823270cb91 100644
--- a/ui/qt/qt.gni
+++ b/ui/qt/qt.gni
@@ -4,9 +4,17 @@
 
 import("//build/config/chromecast_build.gni")
 import("//build/config/sanitizers/sanitizers.gni")
+import("//build/config/sysroot.gni")
 
 declare_args() {
   # TODO(https://crbug.com/1424435): Allow QT in MSAN builds once QT is
   # added to the instrumented libraries.
   use_qt = is_linux && !is_castos && !is_msan
 }
+
+declare_args() {
+  use_qt6 = use_qt && use_sysroot
+}
+
+# use_qt6 => use_qt
+assert(!use_qt6 || use_qt)
diff --git a/ui/qt/qt_shim_moc.cc b/ui/qt/qt5_shim_moc.cc
similarity index 95%
rename from ui/qt/qt_shim_moc.cc
rename to ui/qt/qt5_shim_moc.cc
index dafbfadce56ba..8f8b6b57784a8 100644
--- a/ui/qt/qt_shim_moc.cc
+++ b/ui/qt/qt5_shim_moc.cc
@@ -1,4 +1,4 @@
-// Copyright 2022 The Chromium Authors
+// Copyright 2023 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -89,26 +89,32 @@ const QMetaObject* qt::QtShim::metaObject() const {
 }
 
 void* qt::QtShim::qt_metacast(const char* _clname) {
-  if (!_clname)
+  if (!_clname) {
     return 0;
-  if (!strcmp(_clname, qt_meta_stringdata_qt__QtShim.stringdata))
+  }
+  if (!strcmp(_clname, qt_meta_stringdata_qt__QtShim.stringdata)) {
     return static_cast<void*>(const_cast<QtShim*>(this));
-  if (!strcmp(_clname, "QtInterface"))
+  }
+  if (!strcmp(_clname, "QtInterface")) {
     return static_cast<QtInterface*>(const_cast<QtShim*>(this));
+  }
   return QObject::qt_metacast(_clname);
 }
 
 int qt::QtShim::qt_metacall(QMetaObject::Call _c, int _id, void** _a) {
   _id = QObject::qt_metacall(_c, _id, _a);
-  if (_id < 0)
+  if (_id < 0) {
     return _id;
+  }
   if (_c == QMetaObject::InvokeMetaMethod) {
-    if (_id < 2)
+    if (_id < 2) {
       qt_static_metacall(this, _c, _id, _a);
+    }
     _id -= 2;
   } else if (_c == QMetaObject::RegisterMethodArgumentMetaType) {
-    if (_id < 2)
+    if (_id < 2) {
       *reinterpret_cast<int*>(_a[0]) = -1;
+    }
     _id -= 2;
   }
   return _id;
diff --git a/ui/qt/qt6_shim_moc.cc b/ui/qt/qt6_shim_moc.cc
new file mode 100644
index 0000000000000..6d02ca317b65d
--- /dev/null
+++ b/ui/qt/qt6_shim_moc.cc
@@ -0,0 +1,143 @@
+// Copyright 2023 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/****************************************************************************
+** Meta object code from reading C++ file 'qt_shim.h'
+**
+** Created by: The Qt Meta Object Compiler version 68 (Qt 6.2.4)
+**
+** WARNING! All changes made in this file will be lost!
+*****************************************************************************/
+
+#include <QtCore/qbytearray.h>
+#include <QtCore/qmetatype.h>
+#include <memory>
+#include "ui/qt/qt_shim.h"
+#if !defined(Q_MOC_OUTPUT_REVISION)
+#error "The header file 'qt_shim.h' doesn't include <QObject>."
+#elif Q_MOC_OUTPUT_REVISION != 68
+#error "This file was generated using the moc from 6.2.4. It"
+#error "cannot be used with the include files from this version of Qt."
+#error "(The moc has changed too much.)"
+#endif
+
+QT_BEGIN_MOC_NAMESPACE
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_DEPRECATED
+struct qt_meta_stringdata_qt__QtShim_t {
+  const uint offsetsAndSize[12];
+  char stringdata0[52];
+};
+#define QT_MOC_LITERAL(ofs, len) \
+  uint(offsetof(qt_meta_stringdata_qt__QtShim_t, stringdata0) + ofs), len
+static const qt_meta_stringdata_qt__QtShim_t qt_meta_stringdata_qt__QtShim = {
+    {
+        QT_MOC_LITERAL(0, 10),   // "qt::QtShim"
+        QT_MOC_LITERAL(11, 11),  // "FontChanged"
+        QT_MOC_LITERAL(23, 0),   // ""
+        QT_MOC_LITERAL(24, 4),   // "font"
+        QT_MOC_LITERAL(29, 14),  // "PaletteChanged"
+        QT_MOC_LITERAL(44, 7)    // "palette"
+
+    },
+    "qt::QtShim\0FontChanged\0\0font\0"
+    "PaletteChanged\0palette"};
+#undef QT_MOC_LITERAL
+
+static const uint qt_meta_data_qt__QtShim[] = {
+
+    // content:
+    10,     // revision
+    0,      // classname
+    0, 0,   // classinfo
+    2, 14,  // methods
+    0, 0,   // properties
+    0, 0,   // enums/sets
+    0, 0,   // constructors
+    0,      // flags
+    0,      // signalCount
+
+    // slots: name, argc, parameters, tag, flags, initial metatype offsets
+    1, 1, 26, 2, 0x08, 1 /* Private */, 4, 1, 29, 2, 0x08, 3 /* Private */,
+
+    // slots: parameters
+    QMetaType::Void, QMetaType::QFont, 3, QMetaType::Void, QMetaType::QPalette,
+    5,
+
+    0  // eod
+};
+
+void qt::QtShim::qt_static_metacall(QObject* _o,
+                                    QMetaObject::Call _c,
+                                    int _id,
+                                    void** _a) {
+  if (_c == QMetaObject::InvokeMetaMethod) {
+    auto* _t = static_cast<QtShim*>(_o);
+    (void)_t;
+    switch (_id) {
+      case 0:
+        _t->FontChanged((*reinterpret_cast<std::add_pointer_t<QFont>>(_a[1])));
+        break;
+      case 1:
+        _t->PaletteChanged(
+            (*reinterpret_cast<std::add_pointer_t<QPalette>>(_a[1])));
+        break;
+      default:;
+    }
+  }
+}
+
+const QMetaObject qt::QtShim::staticMetaObject = {
+    {QMetaObject::SuperData::link<QObject::staticMetaObject>(),
+     qt_meta_stringdata_qt__QtShim.offsetsAndSize, qt_meta_data_qt__QtShim,
+     qt_static_metacall, nullptr,
+     qt_incomplete_metaTypeArray<
+         qt_meta_stringdata_qt__QtShim_t,
+         QtPrivate::TypeAndForceComplete<QtShim, std::true_type>,
+         QtPrivate::TypeAndForceComplete<void, std::false_type>,
+         QtPrivate::TypeAndForceComplete<const QFont&, std::false_type>,
+         QtPrivate::TypeAndForceComplete<void, std::false_type>,
+         QtPrivate::TypeAndForceComplete<const QPalette&, std::false_type>
+
+         >,
+     nullptr}};
+
+const QMetaObject* qt::QtShim::metaObject() const {
+  return QObject::d_ptr->metaObject ? QObject::d_ptr->dynamicMetaObject()
+                                    : &staticMetaObject;
+}
+
+void* qt::QtShim::qt_metacast(const char* _clname) {
+  if (!_clname) {
+    return nullptr;
+  }
+  if (!strcmp(_clname, qt_meta_stringdata_qt__QtShim.stringdata0)) {
+    return static_cast<void*>(this);
+  }
+  if (!strcmp(_clname, "QtInterface")) {
+    return static_cast<QtInterface*>(this);
+  }
+  return QObject::qt_metacast(_clname);
+}
+
+int qt::QtShim::qt_metacall(QMetaObject::Call _c, int _id, void** _a) {
+  _id = QObject::qt_metacall(_c, _id, _a);
+  if (_id < 0) {
+    return _id;
+  }
+  if (_c == QMetaObject::InvokeMetaMethod) {
+    if (_id < 2) {
+      qt_static_metacall(this, _c, _id, _a);
+    }
+    _id -= 2;
+  } else if (_c == QMetaObject::RegisterMethodArgumentMetaType) {
+    if (_id < 2) {
+      *reinterpret_cast<QMetaType*>(_a[0]) = QMetaType();
+    }
+    _id -= 2;
+  }
+  return _id;
+}
+QT_WARNING_POP
+QT_END_MOC_NAMESPACE
diff --git a/ui/qt/qt_ui.cc b/ui/qt/qt_ui.cc
index d4052b7e8bc3d..6a3b58e9f930b 100644
--- a/ui/qt/qt_ui.cc
+++ b/ui/qt/qt_ui.cc
@@ -14,7 +14,9 @@
 #include "base/check.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
+#include "base/environment.h"
 #include "base/memory/raw_ptr.h"
+#include "base/nix/xdg_util.h"
 #include "base/notreached.h"
 #include "base/path_service.h"
 #include "base/time/time.h"
@@ -47,6 +49,45 @@ namespace qt {
 
 namespace {
 
+const char kQtVersionFlag[] = "qt-version";
+
+void* LoadLibrary(const base::FilePath& path) {
+  return dlopen(path.value().c_str(), RTLD_NOW | RTLD_GLOBAL);
+}
+
+void* LoadLibraryOrFallback(const base::FilePath& path,
+                            const char* preferred,
+                            const char* fallback) {
+  if (void* library = LoadLibrary(path.Append(preferred))) {
+    return library;
+  }
+  return LoadLibrary(path.Append(fallback));
+}
+
+bool PreferQt6() {
+  auto* cmd = base::CommandLine::ForCurrentProcess();
+  if (cmd->HasSwitch(kQtVersionFlag)) {
+    std::string qt_version_string = cmd->GetSwitchValueASCII(kQtVersionFlag);
+    unsigned int qt_version = 0;
+    if (base::StringToUint(qt_version_string, &qt_version)) {
+      switch (qt_version) {
+        case 5:
+          return false;
+        case 6:
+          return true;
+        default:
+          LOG(ERROR) << "Unsupported QT version " << qt_version;
+      }
+    } else {
+      LOG(ERROR) << "Unable to parse QT version " << qt_version_string;
+    }
+  }
+
+  auto env = base::Environment::Create();
+  auto desktop = base::nix::GetDesktopEnvironment(env.get());
+  return desktop == base::nix::DESKTOP_ENVIRONMENT_KDE6;
+}
+
 int QtWeightToCssWeight(int weight) {
   struct {
     int qt_weight;
@@ -179,8 +220,10 @@ bool QtUi::Initialize() {
   base::FilePath path;
   if (!base::PathService::Get(base::DIR_MODULE, &path))
     return false;
-  path = path.Append("libqt5_shim.so");
-  void* libqt_shim = dlopen(path.value().c_str(), RTLD_NOW | RTLD_GLOBAL);
+  void* libqt_shim =
+      PreferQt6()
+          ? LoadLibraryOrFallback(path, "libqt6_shim.so", "libqt5_shim.so")
+          : LoadLibraryOrFallback(path, "libqt5_shim.so", "libqt6_shim.so");
   if (!libqt_shim)
     return false;
   void* create_qt_interface = dlsym(libqt_shim, "CreateQtInterface");