Defines.Debug vs #if DEBUG

Question

I've started to use a define class like so:

internal sealed class Defines
{
    /// <summary>
    /// This constant is set to true iff the define DEBUG is set.
    /// </summary>
    public const bool Debug =
  #if DEBUG
   true;
  #else
   false;
  #endif
}

The advantages I see is:

1. Ensures I don't break stuff that with an #if..#else..#endif would not be checked by compiler.
2. I can do a find references to see where it is used.
3. It's often useful to have a bool for debug, defines code is longer/more messy.

Possible disadvantage I see:

Compiler can't optimize unused code if the Defines class is in another assembly. Which is why I have made internal.

Am I missing any other disadvantages?

[Edit] Typical examples of usage:

private readonly Permissions _permissions = Defines.Debug ? Permissions.NewAllTrue()
                                                          : Permissions.NewAllFalse();

Or:

var str = string.Format(Defines.Debug ? "{0} {1} ({2})" : "{0} {1}", actual, text, advance);

Answer 1

I see at least one big disadvantage: if Debug is false, this code will cause a warning:

if (Debug)
    Console.WriteLine("Debug");

Because the compiler will detect that the condition is never met, so the Console.WriteLine call is unreachable.