Missing trimming warning when calling instance methods on valuetypes

[MichalStrehovsky]

#113249 (comment)

This should generate a warning:

using System.Diagnostics.CodeAnalysis;

class RequiresHoleTest
{
    public static void Run()
    {
        Helper<C>();
    }

    static T Helper<T>()
    {
        return default(Requires<T>).Do(); // ILLink warns here
    }

    struct Requires<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)] T>
    {
        public T Do()
        {
            return Activator.CreateInstance<T>();
        }
    }

    class C { }
}

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[MichalStrehovsky]

using System.Diagnostics.CodeAnalysis;

class RequiresHoleInterfaceTest
{
    public static void Run()
    {
        Helper<C>();
    }

    static T Helper<T>()
    {
        if (default(Requires<T>) is I<T> i) // ILLink warns here
        {
            return i.Do(); // and here
        }
        return default;
    }

    interface I<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)] T>
    {
        T Do();
    }

    struct Requires<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicParameterlessConstructor)] T> : I<T>
    {
        public T Do()
        {
            return Activator.CreateInstance<T>();
        }
    }

    class C { }
}