QFileSystemModel: don't crash with setIconProvider(nullptr)

The method takes a pointer, so the code shouldn't crash when passed a
nullptr.

QFileInfoGatherer::getInfo() still needs to generate a descriptive
string for the file, so we refactor QAbstractFileIconProvider::type()
to put the implementation into a reusable static function
QAbstractFileIconProviderPrivate::getFileType(const QFileInfo &info).
This unfortunately involves constructing a QMimeDatabase on the fly,
but the docs say that is fine.

Drive-by change: use nullptr instead of `0` for pointers.

Pick-to: 6.5 6.6 6.7
Fixes: QTBUG-99178
Change-Id: Ia32ea0a26701d593e74fbecced7be8d9e0aa0f52
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 7 insertions, 4 deletions

diff --git a/src/widgets/dialogs/qsidebar.cpp b/src/widgets/dialogs/qsidebar.cpp
index 9f6b329a6f..479f5f817d 100644
--- a/src/widgets/dialogs/qsidebar.cpp
+++ b/src/widgets/dialogs/qsidebar.cpp
@@ -183,11 +183,14 @@ void QUrlModel::setUrl(const QModelIndex &index, const QUrl &url, const QModelIn
             setData(index, true, EnabledRole);
         }
 
+        // newIcon could be null if fileSystemModel->iconProvider() returns null
+        if (!newIcon.isNull()) {
         // Make sure that we have at least 32x32 images
-        const QSize size = newIcon.actualSize(QSize(32,32));
-        if (size.width() < 32) {
-            QPixmap smallPixmap = newIcon.pixmap(QSize(32, 32));
-            newIcon.addPixmap(smallPixmap.scaledToWidth(32, Qt::SmoothTransformation));
+            const QSize size = newIcon.actualSize(QSize(32,32));
+            if (size.width() < 32) {
+                QPixmap smallPixmap = newIcon.pixmap(QSize(32, 32));
+                newIcon.addPixmap(smallPixmap.scaledToWidth(32, Qt::SmoothTransformation));
+            }
         }
 
         if (index.data().toString() != newName)