class Program
{
  public static void Main(string[] args)
  {
    foreach (var f in new Func<Foo>[]
    {
      () => new Foo(),
      Foo.CreateNew,
      () => new Bar(), 
      () => new Bar(123)
    })
      try
      {
        Console.WriteLine(f());
      }
      catch(Exception e)
      {
        Console.WriteLine("{0}: {1}", e.GetType(), e.Message);
      }
    Console.WriteLine("done");
    Console.ReadKey(true);
  }
}

class Foo
{
  public Foo()
  {
    var mi = new StackTrace().GetFrame(1).GetMethod();
    if (!mi.IsConstructor) return;
    var t = mi.DeclaringType;
    if (typeof(Foo)!=t &&  typeof(Foo).IsAssignableFrom(t))
      throw new ApplicationException("AARGH!!!111");
  }

  public static Foo CreateNew()=>new Foo();
}

class Bar : Foo
{
  public int N { get; }
  public Bar(int n) => N = n;
  public Bar(){ }
}

class Program
{
  public static void Main(string[] args)
  {
    new Foo().Bar();
    new Foo().Zot();
    var f = new Foo();
    f?.Bar();
    f?.Zot();
    new Zot().Bar();
    new Zot().Zot();
    var z = new Zot();
    z?.Bar();
    z?.Zot();
  }
}

class Foo
{
  public void Bar(){}
  public virtual void Zot(){}
}

sealed class Zot: Foo {}

.method public hidebysig static 
  void Main (
    string[] args
  ) cil managed 
{
  // Method begins at RVA 0x2050
  // Code size 96 (0x60)
  .maxstack 3
  .entrypoint

  IL_0000: newobj instance void test2.Foo::.ctor()
  IL_0005: call instance void test2.Foo::Bar()
  IL_000a: newobj instance void test2.Foo::.ctor()
  IL_000f: callvirt instance void test2.Foo::Zot()
  IL_0014: newobj instance void test2.Foo::.ctor()
  IL_0019: dup
  IL_001a: dup
  IL_001b: brtrue.s IL_0020

  IL_001d: pop
  IL_001e: br.s IL_0025

  IL_0020: call instance void test2.Foo::Bar()

  IL_0025: dup
  IL_0026: brtrue.s IL_002b

  IL_0028: pop
  IL_0029: br.s IL_0030

  IL_002b: callvirt instance void test2.Foo::Zot()

  IL_0030: newobj instance void test2.Zot::.ctor()
  IL_0035: call instance void test2.Foo::Bar()
  IL_003a: newobj instance void test2.Zot::.ctor()
  IL_003f: callvirt instance void test2.Foo::Zot()
  IL_0044: newobj instance void test2.Zot::.ctor()
  IL_0049: dup
  IL_004a: dup
  IL_004b: brtrue.s IL_0050

  IL_004d: pop
  IL_004e: br.s IL_0055

  IL_0050: call instance void test2.Foo::Bar()

  IL_0055: dup
  IL_0056: brtrue.s IL_005a

  IL_0058: pop
  IL_0059: ret

  IL_005a: callvirt instance void test2.Foo::Zot()
  IL_005f: ret
} // end of method Program::Main