C++: Fix resolving of using in enclosing scope

Use-case:
namespace Ns {
namespace Nested {
struct Foo
{
    void func();
    int bar;
};
}
}

using namespace Ns::Nested;

namespace Ns
{
void Foo::func()
{
    bar; // bar not highlighted
}
}

Change-Id: I6e667d63eb40511d65532c4d6d317aa4028a87a4
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/libs/cplusplus/LookupContext.cpp

@@ -1021,7 +1021,7 @@ LookupScope *LookupScope::lookupType(const Name *name, Block *block)
 LookupScope *LookupScope::findType(const Name *name)
 {
     ProcessedSet processed;
-    return d->lookupType_helper(name, &processed, /*searchInEnclosingScope =*/ false, d);
+    return d->lookupType_helper(name, &processed, /*searchInEnclosingScope =*/ true, d);
 }
 
 LookupScope *Internal::LookupScopePrivate::findBlock_helper(

src/plugins/cpptools/cppcompletion_test.cpp

@@ -1551,6 +1551,29 @@ void CppToolsPlugin::test_completion_data()
             << QLatin1String("C")
             << QLatin1String("m"));
 
+    QTest::newRow("type_and_using_declaration: type in nested namespace and using in global") << _(
+            "namespace Ns {\n"
+            "namespace Nested {\n"
+            "struct Foo\n"
+            "{\n"
+            "    void func();\n"
+            "    int m_bar;\n"
+            "};\n"
+            "}\n"
+            "}\n"
+            "\n"
+            "using namespace Ns::Nested;\n"
+            "\n"
+            "namespace Ns\n"
+            "{\n"
+            "void Foo::func()\n"
+            "{\n"
+            "    @\n"
+            "}\n"
+            "}\n"
+        ) << _("m_") << (QStringList()
+            << QLatin1String("m_bar"));
+
     QTest::newRow("instantiate_template_with_anonymous_class") << _(
             "template <typename T>\n"
             "struct S\n"