CDB: Add further checking to avoid invalid set asserts.

Clear a failed call. _HAS_ITERATOR_DEBUGGING can unfortunately
not be turned off as it is not binary compatible with other code.

share/qtcreator/gdbmacros/gdbmacros.cpp

@@ -3178,6 +3178,14 @@ static void qDumpStdSetHelper(QDumper &d)
     const int nn = set.size();
     if (nn < 0)
         return;
+#ifdef Q_CC_MSVC
+    // This set has a head element pointer:
+    // "{ base class ; HeadType *_MyHead ; unsigned int _MySize }",
+    // which is valid even if the set is empty. Check that to avoid iterator asserts.
+    const void *headPtrAddress = addOffset(&set, sizeof(DummyType) - sizeof(unsigned int) - sizeof(void*));
+    if (const void *headPtr = deref(headPtrAddress))
+        qCheckAccess(headPtr);
+#endif
     Q_TYPENAME DummyType::const_iterator it = set.begin();
     const Q_TYPENAME DummyType::const_iterator cend = set.end();
     for (int i = 0; i < nn && i < 10 && it != cend; ++i, ++it)

src/plugins/debugger/cdb/cdbdumperhelper.cpp

@@ -563,8 +563,14 @@ CdbDumperHelper::CallResult
         if (!writeToDebuggee(m_cif->debugDataSpaces, inBuffer, m_inBufferAddress, errorMessage))
             return CallFailed;
     }
-    if (!CdbDebugEnginePrivate::executeDebuggerCommand(m_cif->debugControl, callCmd, errorMessage))
+    if (!CdbDebugEnginePrivate::executeDebuggerCommand(m_cif->debugControl, callCmd, errorMessage)) {
+        // Clear the outstanding call in case we triggered a debug library assert with a message box
+        QString clearError;
+        if (!CdbDebugEnginePrivate::executeDebuggerCommand(m_cif->debugControl, QLatin1String(".call /c"), &clearError)) {
+            *errorMessage += QString::fromLatin1("/Unable to clear call %1").arg(clearError);
+        }
         return CallSyntaxError;
+    }
     // Set up call and a temporary breakpoint after it.
     // Try to skip debuggee crash exceptions and dumper exceptions
     // by using 'gN' (go not handled -> pass handling to dumper __try/__catch block)