C++: Fix decltype resolving for nested instantiated class

The enclosingScope of a cloned nested class is not the
original class but the cloned parent.

Use-case:
template <typename T>
struct Temp
{
    struct Nested
    {
        static T f();
        typedef decltype(f()) type;
    };
};

struct Foo { int bar; };

void fun()
{
    Temp<Foo>::Nested::type s;
    s.bar; // bar not highlighted
}

Task-number: QTCREATORBUG-14483
Change-Id: I3e15399a78a7492f740db8d0c7d5c84adf77d1d0
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/plugins/cpptools/cppcompletion_test.cpp b/src/plugins/cpptools/cppcompletion_test.cpp
index 2fab0bed6e..e9c35198cb 100644
--- a/src/plugins/cpptools/cppcompletion_test.cpp
+++ b/src/plugins/cpptools/cppcompletion_test.cpp
@@ -2962,6 +2962,28 @@ void CppToolsPlugin::test_completion_data()
     ) << _("s.") << (QStringList()
             << QLatin1String("Foo")
             << QLatin1String("bar"));
+
+    QTest::newRow("nested_instantiation_typedefed_decltype_declaration") << _(
+            "template <typename T>\n"
+            "struct Temp\n"
+            "{\n"
+            "    struct Nested\n"
+            "    {\n"
+            "        static T f();\n"
+            "        typedef decltype(f()) type;\n"
+            "    };\n"
+            "};\n"
+            "\n"
+            "struct Foo { int bar; };\n"
+            "\n"
+            "void fun()\n"
+            "{\n"
+            "    Temp<Foo>::Nested::type s;\n"
+            "    @\n"
+            "}\n"
+    ) << _("s.") << (QStringList()
+            << QLatin1String("Foo")
+            << QLatin1String("bar"));
 }
 
 void CppToolsPlugin::test_completion_member_access_operator()