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, 23 insertions, 3 deletions

diff --git a/tests/auto/corelib/plugin/qpluginloader/tst_qpluginloader.cpp b/tests/auto/corelib/plugin/qpluginloader/tst_qpluginloader.cpp
index e6d1785dca..f4714af91f 100644
--- a/tests/auto/corelib/plugin/qpluginloader/tst_qpluginloader.cpp
+++ b/tests/auto/corelib/plugin/qpluginloader/tst_qpluginloader.cpp
@@ -278,7 +278,9 @@ void tst_QPluginLoader::errorString()
     QVERIFY(!unloaded);
     }
 
-#if !defined(Q_OS_WIN) && !defined(Q_OS_DARWIN) && !defined(Q_OS_HPUX)
+// A bug in QNX causes the test to crash on exit after attempting to load
+// a shared library with undefined symbols (tracked as QTBUG-114682).
+#if !defined(Q_OS_WIN) && !defined(Q_OS_DARWIN) && !defined(Q_OS_HPUX) && !defined(Q_OS_QNX)
     {
     QPluginLoader loader( sys_qualifiedLibraryName("almostplugin"));     //a plugin with unresolved symbols
     loader.setLoadHints(QLibrary::ResolveAllSymbolsHint);
@@ -338,16 +340,34 @@ void tst_QPluginLoader::loadHints()
     QCOMPARE(loader.loadHints(), QLibrary::PreventUnloadHint);   //Do not crash
     loader.setLoadHints(QLibrary::ResolveAllSymbolsHint);
     QCOMPARE(loader.loadHints(), QLibrary::ResolveAllSymbolsHint);
+    // We can clear load hints when file name is not set.
+    loader.setLoadHints(QLibrary::LoadHints{});
+    QCOMPARE(loader.loadHints(), QLibrary::LoadHints{});
+    // Set the hints again
+    loader.setLoadHints(QLibrary::ResolveAllSymbolsHint);
+    QCOMPARE(loader.loadHints(), QLibrary::ResolveAllSymbolsHint);
     loader.setFileName( sys_qualifiedLibraryName("theplugin"));     //a plugin
     QCOMPARE(loader.loadHints(), QLibrary::ResolveAllSymbolsHint);
 
+    QPluginLoader loader4;
+    QCOMPARE(loader4.loadHints(), QLibrary::PreventUnloadHint);
+    loader4.setLoadHints(QLibrary::LoadHints{});
+    QCOMPARE(loader4.loadHints(), QLibrary::LoadHints{});
+    loader4.setFileName(sys_qualifiedLibraryName("theplugin"));
+    // Hints are merged with hints from the previous loader.
+    QCOMPARE(loader4.loadHints(), QLibrary::ResolveAllSymbolsHint);
+    // We cannot clear load hints after associating the loader with a file.
+    loader.setLoadHints(QLibrary::LoadHints{});
+    QCOMPARE(loader.loadHints(), QLibrary::ResolveAllSymbolsHint);
+
     QPluginLoader loader2;
     QCOMPARE(loader2.loadHints(), QLibrary::PreventUnloadHint);
     loader2.setFileName(sys_qualifiedLibraryName("theplugin"));
-    QCOMPARE(loader2.loadHints(), QLibrary::PreventUnloadHint);
+    // Hints are merged with hints from previous loaders.
+    QCOMPARE(loader2.loadHints(), QLibrary::PreventUnloadHint | QLibrary::ResolveAllSymbolsHint);
 
     QPluginLoader loader3(sys_qualifiedLibraryName("theplugin"));
-    QCOMPARE(loader3.loadHints(), QLibrary::PreventUnloadHint);
+    QCOMPARE(loader3.loadHints(), QLibrary::PreventUnloadHint | QLibrary::ResolveAllSymbolsHint);
 }
 
 void tst_QPluginLoader::deleteinstanceOnUnload()