Comment # 6 on bug 179 from Iain Buclaw

Reduced:
---
struct SignalImpl
{
    @disable this(this);
}

struct RestrictedSignal
{
    SignalImpl mImpl;
    void connect() { }
}

struct Signal
{
    RestrictedSignal mRestricted;
}

class MyObject
{
    Signal valueChangedSg;
    ref RestrictedSignal valueChanged()
    {
        return valueChangedSg.mRestricted;
    }
}

int main ()
{
    MyObject a = new MyObject;
    a.valueChanged().connect();
    return 0;
}