QLibraryInfo: port from manual memory management to unique_ptr

It's safer and clearer.

Also standardize on unique_ptr instead of QScopedPointer, because the
latter is not supposed to be movable, so the assignment in
QLibrarySettings::load() would not compile.

As a drive-by, scope a variable tighter (in an if condition).

Task-number: QTBUG-132213
Pick-to: 6.8
Change-Id: Iecdd910af4d06dbd03d2daf3ccf99dd4822f04ac
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit aa1f2064801b39a26a718703817e197a3e31447e)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/global/qlibraryinfo.cpp

@@ -10,7 +10,6 @@
 #endif
 #include "qlibraryinfo.h"
 #include "qlibraryinfo_p.h"
-#include "qscopedpointer.h"
 
 #include "qcoreapplication.h"
 
@@ -30,6 +29,8 @@
 #    include <qt_windows.h>
 #endif
 
+#include <memory>
+
 QT_BEGIN_NAMESPACE
 
 using namespace Qt::StringLiterals;
@@ -38,7 +39,7 @@ extern void qDumpCPUFeatures(); // in qsimd.cpp
 
 #if QT_CONFIG(settings)
 
-static QSettings *findConfiguration();
+static std::unique_ptr<QSettings> findConfiguration();
 
 struct QLibrarySettings
 {
@@ -47,7 +48,7 @@ struct QLibrarySettings
     bool havePaths();
     QSettings *configuration();
 
-    QScopedPointer<QSettings> settings;
+    std::unique_ptr<QSettings> settings;
     bool paths;
     bool reloadOnQAppAvailable;
 };
@@ -62,7 +63,7 @@ QSettings *QLibrarySettings::configuration()
 {
     if (reloadOnQAppAvailable && QCoreApplication::instance() != nullptr)
         load();
-    return settings.data();
+    return settings.get();
 }
 
 bool QLibrarySettings::havePaths()
@@ -75,8 +76,8 @@ bool QLibrarySettings::havePaths()
 void QLibrarySettings::load()
 {
     // If we get any settings here, those won't change when the application shows up.
-    settings.reset(findConfiguration());
+    settings = findConfiguration();
-    reloadOnQAppAvailable = (settings.data() == nullptr && QCoreApplication::instance() == nullptr);
+    reloadOnQAppAvailable = !settings && !QCoreApplication::instance();
 
     if (settings) {
         // This code needs to be in the regular library, as otherwise a qt.conf that
@@ -96,14 +97,14 @@ void QLibraryInfoPrivate::setQtconfManualPath(const QString *path)
     qtconfManualPath = path;
 }
 
-static QSettings *findConfiguration()
+static std::unique_ptr<QSettings> findConfiguration()
 {
     if (qtconfManualPath)
-        return new QSettings(*qtconfManualPath, QSettings::IniFormat);
+        return std::make_unique<QSettings>(*qtconfManualPath, QSettings::IniFormat);
 
     QString qtconfig = QStringLiteral(":/qt/etc/qt.conf");
     if (QFile::exists(qtconfig))
-        return new QSettings(qtconfig, QSettings::IniFormat);
+        return std::make_unique<QSettings>(qtconfig, QSettings::IniFormat);
 #ifdef Q_OS_DARWIN
     CFBundleRef bundleRef = CFBundleGetMainBundle();
     if (bundleRef) {
@@ -115,7 +116,7 @@ static QSettings *findConfiguration()
             QCFString path = CFURLCopyFileSystemPath(urlRef, kCFURLPOSIXPathStyle);
             qtconfig = QDir::cleanPath(path);
             if (QFile::exists(qtconfig))
-                return new QSettings(qtconfig, QSettings::IniFormat);
+                return std::make_unique<QSettings>(qtconfig, QSettings::IniFormat);
         }
     }
 #endif
@@ -123,10 +124,10 @@ static QSettings *findConfiguration()
         QDir pwd(QCoreApplication::applicationDirPath());
         qtconfig = pwd.filePath(u"qt" QT_STRINGIFY(QT_VERSION_MAJOR) ".conf"_s);
         if (QFile::exists(qtconfig))
-            return new QSettings(qtconfig, QSettings::IniFormat);
+            return std::make_unique<QSettings>(qtconfig, QSettings::IniFormat);
         qtconfig = pwd.filePath("qt.conf"_L1);
         if (QFile::exists(qtconfig))
-            return new QSettings(qtconfig, QSettings::IniFormat);
+            return std::make_unique<QSettings>(qtconfig, QSettings::IniFormat);
     }
     return nullptr;     //no luck
 }
@@ -688,8 +689,7 @@ QString QLibraryInfoPrivate::path(QLibraryInfo::LibraryPath p, UsageMode usageMo
 QStringList QLibraryInfo::platformPluginArguments(const QString &platformName)
 {
 #if QT_CONFIG(settings)
-    QScopedPointer<const QSettings> settings(findConfiguration());
+    if (const auto settings = findConfiguration()) {
-    if (!settings.isNull()) {
         const QString key = "Platforms/"_L1
                 + platformName
                 + "Arguments"_L1;