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, 0 deletions

diff --git a/src/gui/itemmodels/qfilesystemmodel_p.h b/src/gui/itemmodels/qfilesystemmodel_p.h
index 7c9e41622e..e01b0d56e6 100644
--- a/src/gui/itemmodels/qfilesystemmodel_p.h
+++ b/src/gui/itemmodels/qfilesystemmodel_p.h
@@ -150,8 +150,12 @@ public:
             return visibleChildren.indexOf(childName);
         }
         void updateIcon(QAbstractFileIconProvider *iconProvider, const QString &path) {
+            if (!iconProvider)
+                return;
+
             if (info)
                 info->icon = iconProvider->icon(QFileInfo(path));
+
             for (QFileSystemNode *child : std::as_const(children)) {
                 //On windows the root (My computer) has no path so we don't want to add a / for nothing (e.g. /C:/)
                 if (!path.isEmpty()) {
@@ -165,6 +169,9 @@ public:
         }
 
         void retranslateStrings(QAbstractFileIconProvider *iconProvider, const QString &path) {
+            if (!iconProvider)
+                return;
+
             if (info)
                 info->displayType = iconProvider->type(QFileInfo(path));
             for (QFileSystemNode *child : std::as_const(children)) {