C++: fix code completion when 'using' declaration inside function

Looking for using declaration when lookup a type

Task-number: QTCREATORBUG-2668
Change-Id: I11600c5be262840472dd4c9e72334760a35aa4a0
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/libs/cplusplus/LookupContext.cpp

@@ -309,6 +309,15 @@ ClassOrNamespace *LookupContext::lookupType(const Name *name, Scope *scope,
                             return lookupType(namedTy->name(), scope);
                     }
                 }
+            } else if (UsingDeclaration *ud = m->asUsingDeclaration()) {
+                if (name->isNameId()) {
+                    if (const QualifiedNameId *q = ud->name()->asQualifiedNameId()) {
+                        if (q->name()->isEqualTo(name)) {
+                            return bindings()->globalNamespace()->lookupType(q);
+                        }
+                    }
+
+                }
             }
         }
         return lookupType(name, scope->enclosingScope());

src/plugins/cpptools/cppcompletion_test.cpp

@@ -1882,3 +1882,136 @@ void CppToolsPlugin::test_completion_QTCREATORBUG9098()
     QVERIFY(completions.contains(QLatin1String("c")));
     QVERIFY(completions.contains(QLatin1String("B")));
 }
+
+void CppToolsPlugin::test_completion_type_and_using_declaration()
+{
+    test_completion();
+}
+
+void CppToolsPlugin::test_completion_type_and_using_declaration_data()
+{
+    QTest::addColumn<QByteArray>("code");
+    QTest::addColumn<QStringList>("expectedCompletions");
+
+    QByteArray code;
+    QStringList completions;
+
+    code = "\n"
+            "namespace NS\n"
+            "{\n"
+            "struct C { int m; };\n"
+            "}\n"
+            "void foo()\n"
+            "{\n"
+            "    using NS::C;\n"
+            "    C c;\n"
+            "    @\n"
+            "    // padding so we get the scope right\n"
+            "}\n";
+    completions.append(QLatin1String("C"));
+    completions.append(QLatin1String("m"));
+    QTest::newRow("case: type and using declaration inside function")
+            << code << completions;
+
+    completions.clear();
+
+    code = "\n"
+            "namespace NS\n"
+            "{\n"
+            "struct C { int m; };\n"
+            "}\n"
+            "using NS::C;\n"
+            "void foo()\n"
+            "{\n"
+            "    C c;\n"
+            "    @\n"
+            "    // padding so we get the scope right\n"
+            "}\n";
+    completions.append(QLatin1String("C"));
+    completions.append(QLatin1String("m"));
+    QTest::newRow("case: type and using declaration in global namespace")
+            << code << completions;
+
+    completions.clear();
+
+    code = "\n"
+            "struct C { int m; };\n"
+            "namespace NS\n"
+            "{\n"
+            "   using ::C;\n"
+            "   void foo()\n"
+            "   {\n"
+            "       C c;\n"
+            "       @\n"
+            "       // padding so we get the scope right\n"
+            "   }\n"
+            "}\n";
+    completions.append(QLatin1String("C"));
+    completions.append(QLatin1String("m"));
+    QTest::newRow("case: type in global namespace and using declaration in NS namespace")
+            << code << completions;
+
+    completions.clear();
+
+    code = "\n"
+            "struct C { int m; };\n"
+            "namespace NS\n"
+            "{\n"
+            "   void foo()\n"
+            "   {\n"
+            "       using ::C;\n"
+            "       C c;\n"
+            "       @\n"
+            "       // padding so we get the scope right\n"
+            "   }\n"
+            "}\n";
+    completions.append(QLatin1String("C"));
+    completions.append(QLatin1String("m"));
+    QTest::newRow("case: type in global namespace and using declaration inside function in NS namespace")
+            << code << completions;
+
+    completions.clear();
+
+    code = "\n"
+            "namespace NS1\n"
+            "{\n"
+            "struct C { int m; };\n"
+            "}\n"
+            "namespace NS2\n"
+            "{\n"
+            "   void foo()\n"
+            "   {\n"
+            "       using NS1::C;\n"
+            "       C c;\n"
+            "       @\n"
+            "       // padding so we get the scope right\n"
+            "   }\n"
+            "}\n";
+    completions.append(QLatin1String("C"));
+    completions.append(QLatin1String("m"));
+    QTest::newRow("case: type inside namespace NS1 and using declaration in function inside NS2 namespace")
+            << code << completions;
+
+    completions.clear();
+
+    code = "\n"
+            "namespace NS1\n"
+            "{\n"
+            "struct C { int m; };\n"
+            "}\n"
+            "namespace NS2\n"
+            "{\n"
+            "   using NS1::C;\n"
+            "   void foo()\n"
+            "   {\n"
+            "       C c;\n"
+            "       @\n"
+            "       // padding so we get the scope right\n"
+            "   }\n"
+            "}\n";
+    completions.append(QLatin1String("C"));
+    completions.append(QLatin1String("m"));
+    QTest::newRow("case: type inside namespace NS1 and using declaration inside NS2 namespace")
+            << code << completions;
+
+}

src/plugins/cpptools/cpptoolsplugin.h

@@ -124,6 +124,8 @@ private slots:
     void test_completion_typedef_using_templates2();
     void test_completion_namespace_alias_with_many_namespace_declarations();
     void test_completion_QTCREATORBUG9098();
+    void test_completion_type_and_using_declaration();
+    void test_completion_type_and_using_declaration_data();
 
     void test_format_pointerdeclaration_in_simpledeclarations();
     void test_format_pointerdeclaration_in_simpledeclarations_data();