class C
{
    const int N = 10;
    void M()
    {
        var lam = (int x = N) => x;
    }
}

In the following case, N is shown as unused in the IDE, when its usage as a default parameter value for the lambda should be tracked. We are already removing unused variable warnings when they occur for local constants used as default parameter values for lambdas and local functions in the compiler: #63850