CppEditor: Harden FunctionHelper::overrides

Task-number: QTCREATORBUG-10333

Change-Id: I2ba7e0d5b8b8eb856445e737dfa21ec8a543f85d
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cppeditor/cppvirtualfunctionassistprovider.cpp

@@ -282,13 +282,14 @@ bool FunctionHelper::isPureVirtualFunction(const Function *function, const Snaps
 }
 
 QList<Symbol *> FunctionHelper::overrides(Class *startClass, Function *function,
-                                           const Snapshot &snapshot)
+                                          const Snapshot &snapshot)
 {
     QList<Symbol *> result;
-    QTC_ASSERT(function && startClass, return result);
+    QTC_ASSERT(startClass && function, return result);
 
     FullySpecifiedType referenceType = function->type();
     const Name *referenceName = function->name();
+    QTC_ASSERT(referenceName && referenceType.isValid(), return result);
 
     // Add itself
     result << function;
@@ -315,7 +316,9 @@ QList<Symbol *> FunctionHelper::overrides(Class *startClass, Function *function,
         for (int i = 0, total = c->memberCount(); i < total; ++i) {
             Symbol *candidate = c->memberAt(i);
             const Name *candidateName = candidate->name();
-            FullySpecifiedType candidateType = candidate->type();
+            const FullySpecifiedType candidateType = candidate->type();
+            if (!candidateName || !candidateType.isValid())
+                continue;
             if (candidateName->isEqualTo(referenceName) && candidateType.isEqualTo(referenceType))
                 result << candidate;
         }