QLibraryPrivate: Actually merge load hints

Or old and new load hints in mergeLoadHints() instead of just storing
new ones. Andjust QLibraryPrivate::setLoadHints() to handle objects
with no file name differently and just set load hints directly.

Mention that load hints are merged once the file name is set
in the documentation for QLibrary::setLoadHints().

Add a regression test into tst_qfactoryloader.

Update and extend tst_QPluginLoader::loadHints() to take into account
load hints merging.

Fixes: QTBUG-114480
Change-Id: I3b9afaec7acde1f5ff992d913f8d7217392c7e00
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index f34a03db0e..56371a7aa0 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -465,7 +465,7 @@ void QLibraryPrivate::mergeLoadHints(QLibrary::LoadHints lh)
     if (pHnd.loadRelaxed())
         return;
 
-    loadHintsInt.storeRelaxed(lh.toInt());
+    loadHintsInt.fetchAndOrRelaxed(lh.toInt());
 }
 
 QFunctionPointer QLibraryPrivate::resolve(const char *symbol)
@@ -477,6 +477,13 @@ QFunctionPointer QLibraryPrivate::resolve(const char *symbol)
 
 void QLibraryPrivate::setLoadHints(QLibrary::LoadHints lh)
 {
+    // Set the load hints directly for a dummy if this object is not associated
+    // with a file. Such object is not shared between multiple instances.
+    if (fileName.isEmpty()) {
+        loadHintsInt.storeRelaxed(lh.toInt());
+        return;
+    }
+
     // this locks a global mutex
     QMutexLocker lock(&qt_library_mutex);
     mergeLoadHints(lh);
@@ -1113,6 +1120,10 @@ QString QLibrary::errorString() const
     lazy symbol resolution, and will not export external symbols for resolution
     in other dynamically-loaded libraries.
 
+    \note Hints can only be cleared when this object is not associated with a
+    file. Hints can only be added once the file name is set (\a hints will
+    be or'ed with the old hints).
+
     \note Setting this property after the library has been loaded has no effect
     and loadHints() will not reflect those changes.