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>

2 files changed, 16 insertions, 2 deletions

diff --git a/tests/manual/dialogs/filedialogpanel.cpp b/tests/manual/dialogs/filedialogpanel.cpp
index 6f807d9280..47a1b54ae3 100644
--- a/tests/manual/dialogs/filedialogpanel.cpp
+++ b/tests/manual/dialogs/filedialogpanel.cpp
@@ -86,6 +86,7 @@ FileDialogPanel::FileDialogPanel(QWidget *parent)
     , m_resolveSymLinks(new QCheckBox(tr("Resolve symlinks")))
     , m_native(new QCheckBox(tr("Use native dialog")))
     , m_customDirIcons(new QCheckBox(tr("Don't use custom directory icons")))
+    , m_noIconProvider(new QCheckBox(tr("Null icon provider")))
     , m_acceptMode(createCombo(this, acceptModeComboData, sizeof(acceptModeComboData)/sizeof(FlagData)))
     , m_fileMode(createCombo(this, fileModeComboData, sizeof(fileModeComboData)/sizeof(FlagData)))
     , m_viewMode(createCombo(this, viewModeComboData, sizeof(viewModeComboData)/sizeof(FlagData)))
@@ -113,6 +114,7 @@ FileDialogPanel::FileDialogPanel(QWidget *parent)
     optionsLayout->addRow(m_resolveSymLinks);
     optionsLayout->addRow(m_readOnly);
     optionsLayout->addRow(m_customDirIcons);
+    optionsLayout->addRow(m_noIconProvider);
 
     // Files
     QGroupBox *filesGroupBox = new QGroupBox(tr("Files / Filters"));
@@ -417,12 +419,19 @@ void FileDialogPanel::restoreDefaults()
         l->restoreDefault(&d);
 }
 
-void FileDialogPanel::applySettings(QFileDialog *d) const
+void FileDialogPanel::applySettings(QFileDialog *d)
 {
     d->setAcceptMode(comboBoxValue<QFileDialog::AcceptMode>(m_acceptMode));
     d->setViewMode(comboBoxValue<QFileDialog::ViewMode>(m_viewMode));
     d->setFileMode(comboBoxValue<QFileDialog::FileMode>(m_fileMode));
     d->setOptions(options());
+    if (m_noIconProvider->isChecked()) {
+        m_origIconProvider = d->iconProvider();
+        d->setIconProvider(nullptr);
+    } else if (m_origIconProvider) {
+        d->setIconProvider(m_origIconProvider);
+    }
+
     d->setDefaultSuffix(m_defaultSuffix->text().trimmed());
     const QString directory = m_directory->text().trimmed();
     if (!directory.isEmpty())
diff --git a/tests/manual/dialogs/filedialogpanel.h b/tests/manual/dialogs/filedialogpanel.h
index 1cce1dfdd1..ec36835f6e 100644
--- a/tests/manual/dialogs/filedialogpanel.h
+++ b/tests/manual/dialogs/filedialogpanel.h
@@ -9,6 +9,8 @@
 #include <QPointer>
 
 QT_BEGIN_NAMESPACE
+
+class QAbstractFileIconProvider;
 class QPushButton;
 class QCheckBox;
 class QComboBox;
@@ -52,7 +54,7 @@ private:
     QString filterString() const;
     QFileDialog::Options options() const;
     QStringList allowedSchemes() const;
-    void applySettings(QFileDialog *d) const;
+    void applySettings(QFileDialog *d);
 
     QFormLayout *filesLayout;
     QCheckBox *m_showDirsOnly;
@@ -62,6 +64,9 @@ private:
     QCheckBox *m_resolveSymLinks;
     QCheckBox *m_native;
     QCheckBox *m_customDirIcons;
+    QCheckBox *m_noIconProvider = nullptr;
+    QAbstractFileIconProvider *m_origIconProvider = nullptr;
+
     QComboBox *m_acceptMode;
     QComboBox *m_fileMode;
     QComboBox *m_viewMode;