Add QComHelper class for dealing with COM on Windows

Unifies our approach to calling CoInitializeEx and CoUninitialize,
removing a lot of boilerplate in the process, and also fixes a few
bugs where we would incorrectly balance our calls to CoInitializeEx
and CoUninitialize.

The optimistic approach of qfilesystemengine_win.cpp of calling
CoCreateInstance without initializing the COM library explicitly
has been removed, as calling CoInitializeEx should be a noop in
the situation where it's already been loaded.

Change-Id: I9e2ec101678c2ebb9946504b5e8034e58f1bb56a
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/plugins/platforms/windows/qwindowsservices.cpp b/src/plugins/platforms/windows/qwindowsservices.cpp
index f2bd90f4bd..2c84204d2b 100644
--- a/src/plugins/platforms/windows/qwindowsservices.cpp
+++ b/src/plugins/platforms/windows/qwindowsservices.cpp
@@ -12,6 +12,7 @@
 #include <QtCore/qthread.h>
 
 #include <QtCore/private/qwinregistry_p.h>
+#include <QtCore/private/qfunctions_win_p.h>
 
 #include <shlobj.h>
 #include <shlwapi.h>
@@ -34,11 +35,10 @@ public:
 
     void run() override
     {
-        if (SUCCEEDED(CoInitializeEx(NULL, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE))) {
+        QComHelper comHelper;
+        if (comHelper.isValid())
             m_result = ShellExecute(nullptr, m_operation, m_file, m_parameters, nullptr,
                                     SW_SHOWNORMAL);
-            CoUninitialize();
-        }
     }
 
     HINSTANCE result() const { return m_result; }