struct Foo { int bar; };
Foo foo() { return Foo; }
typedef decltype(foo()) TypedefedFooWithDecltype;

template <typename _Tp>
struct Temp
{
    struct Nested
    {
        static _Tp f();
        typedef decltype(f()) type;
    };
    typedef typename Nested::type type;
};

void fun()
{
    // simple
    decltype(foo()) decltypeFoo;
    decltypeFoo.;// code completion should work here

    // typedef
    TypedefedFooWithDecltype typedefedFooWithDecltype;
    typedefedFooWithDecltype.;// code completion should work here

    // nested instantiation typedef
    Temp<Foo>::type nestedDeclType;
    nestedDeclType.; // code completion should work here
}