QFileInfoGatherer: Fix internal build (with Q_AUTOTEST_EXPORT)

I'm surprised that this passed the CI on Windows, because
Q_AUTOTEST_EXPORT is Q_DECL_EXPORT, which is __declspec(dllexport) and
all dllexport'ed functions must be defined in the current DLL, not
imported from elsewhere. This is similar on Unix systems with the
no_direct_extern_access mode, because then Q_DECL_EXPORT behaves like on
Windows.

That means Qt modules can't call a Q_AUTOTEST_EXPORT function
from another module (only tests can). Solve this by providing a function
that is properly exported with Q_CORE_EXPORT.

Amends commit 3d08816.

Pick-to: 6.8
Task-number: QTBUG-28246
Task-number: QTBUG-31103
Change-Id: I2ba317ab34bda8c18954fffd28395f7354cb54f2
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/corelib/io/qfilesystemengine.cpp

@@ -143,6 +143,12 @@ static bool _q_createLegacyEngine_recursive(QFileSystemEntry &entry, QFileSystem
     return _q_checkEntry(entry, data, resolvingEntry);
 }
 
+Q_CORE_EXPORT bool qt_isCaseSensitive(const QFileSystemEntry &entry, QFileSystemMetaData &data)
+{
+    // called from QtGui (QFileSystemModel, QFileInfoGatherer)
+    return QFileSystemEngine::isCaseSensitive(entry, data);
+}
+
 /*!
     \internal
 

src/corelib/io/qfilesystemengine_p.h

@@ -55,12 +55,11 @@ inline bool qIsFilenameBroken(const QFileSystemEntry &entry)
             Q_RETURN_ON_INVALID_FILENAME("Broken filename passed to function", (result)); \
     } while (false)
 
+Q_CORE_EXPORT bool qt_isCaseSensitive(const QFileSystemEntry &entry, QFileSystemMetaData &data);
+
 class Q_AUTOTEST_EXPORT QFileSystemEngine
 {
 public:
-#ifndef QT_BUILD_INTERNAL
-    Q_CORE_EXPORT
-#endif
     static bool isCaseSensitive(const QFileSystemEntry &entry, QFileSystemMetaData &data);
 
     static QFileSystemEntry getLinkTarget(const QFileSystemEntry &link, QFileSystemMetaData &data);

src/gui/itemmodels/qfileinfogatherer_p.h

@@ -59,7 +59,7 @@ class QExtendedInformation {
 #ifndef QT_NO_FSFILEENGINE
     bool isCaseSensitive() const {
         auto *fiPriv = QFileInfoPrivate::get(const_cast<QFileInfo*>(&mFileInfo));
-        return QFileSystemEngine::isCaseSensitive(fiPriv->fileEntry, fiPriv->metaData);
+        return qt_isCaseSensitive(fiPriv->fileEntry, fiPriv->metaData);
     }
 #endif
 

tests/auto/gui/itemmodels/qfilesystemmodel/tst_qfilesystemmodel.cpp

@@ -1058,7 +1058,7 @@ void tst_QFileSystemModel::caseSensitivity()
 
     QFileInfo tmpInfo(tmp);
     auto *tmpInfoPriv = QFileInfoPrivate::get(&tmpInfo);
-    if (!QFileSystemEngine::isCaseSensitive(tmpInfoPriv->fileEntry, tmpInfoPriv->metaData)) {
+    if (!qt_isCaseSensitive(tmpInfoPriv->fileEntry, tmpInfoPriv->metaData)) {
         // Verify that files can be accessed by paths with fLipPeD case.
         for (int i = 0; i < paths.size(); ++i) {
             const QModelIndex normalCaseIndex = indexes.at(i);