CppTools: Hide "QPrivateSignal" on signal completion (Qt5)

See also http://woboq.com/blog/how-qt-signals-slots-work-part2-qt5.html

Task-number: QTCREATORBUG-8540
Change-Id: Iccad837d7a0da982e7d7a1eda95ff1828cf1dce6
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>

src/plugins/cpptools/cppcompletion_test.cpp

@@ -2463,3 +2463,36 @@ void CppToolsPlugin::test_completion_recursive_using_typedef_declarations()
 
     QCOMPARE(completions.size(), 0);
 }
+
+void CppToolsPlugin::test_completion_signals_hide_QPrivateSignal()
+{
+    const QByteArray source =
+        "#define SIGNAL(a) #a\n"
+        "#define SLOT(a) #a\n"
+        "#define signals public\n"
+        "#define Q_OBJECT struct QPrivateSignal {};\n"
+        "\n"
+        "class QObject\n"
+        "{\n"
+        "public:\n"
+        "    void connect(QObject *, char *, QObject *, char *);\n"
+        "};\n"
+        "\n"
+        "class Timer : public QObject\n"
+        "{\n"
+        "    Q_OBJECT\n"
+        "signals:\n"
+        "    void timeout(QPrivateSignal);\n"
+        "};\n"
+        "\n"
+        "void client()\n"
+        "{\n"
+        "    Timer *timer = new Timer;\n"
+        "    connect(timer, SIGNAL(@\n"
+        "}\n";
+    CompletionTestCase test(source);
+
+    const QStringList completions = test.getCompletions();
+    QCOMPARE(completions.size(), 1);
+    QVERIFY(completions.contains(QLatin1String("timeout()")));
+}

src/plugins/cpptools/cppcompletionassist.cpp

@@ -602,6 +602,24 @@ Function *asFunctionOrTemplateFunctionType(FullySpecifiedType ty)
     return 0;
 }
 
+bool isQPrivateSignal(const Symbol *symbol)
+{
+    if (!symbol)
+        return false;
+
+    static Identifier qPrivateSignalIdentifier("QPrivateSignal", 14);
+
+    if (FullySpecifiedType type = symbol->type()) {
+        if (NamedType *namedType = type->asNamedType()) {
+            if (const Name *name = namedType->name()) {
+                if (name->isEqualTo(&qPrivateSignalIdentifier))
+                    return true;
+            }
+        }
+    }
+    return false;
+}
+
 } // Anonymous
 
 // ----------------------------
@@ -1620,6 +1638,8 @@ bool CppCompletionAssistProcessor::completeQtMethod(const QList<CPlusPlus::Looku
                     signature += QLatin1Char('(');
                     for (unsigned i = 0; i < count; ++i) {
                         Symbol *arg = fun->argumentAt(i);
+                        if (isQPrivateSignal(arg))
+                            continue;
                         if (i != 0)
                             signature += QLatin1Char(',');
                         signature += o.prettyType(arg->type());

src/plugins/cpptools/cpptoolsplugin.h

@@ -148,6 +148,8 @@ private slots:
     void test_completion_recursive_using_declarations2();
     void test_completion_recursive_using_typedef_declarations();
 
+    void test_completion_signals_hide_QPrivateSignal();
+
     void test_format_pointerdeclaration_in_simpledeclarations();
     void test_format_pointerdeclaration_in_simpledeclarations_data();
     void test_format_pointerdeclaration_in_controlflowstatements();