Can .NET source code hard-code a debugging breakpoint?

You probably are after something like this:

if(System.Diagnostics.Debugger.IsAttached)
  System.Diagnostics.Debugger.Break();

Of course that will still get compiled in a Release build. If you want it to behave more like the Debug object where the code simply doesn’t exist in a Release build, then you could do something like this:

    // Conditional("Debug") means that calls to DebugBreak will only be
    // compiled when Debug is defined. DebugBreak will still be compiled
    // even in release mode, but the #if eliminates the code within it.
    // DebuggerHidden is so that, when the break happens, the call stack
    // is at the caller rather than inside of DebugBreak.
    [DebuggerHidden]
    [Conditional("DEBUG")] 
    void DebugBreak()
    {
        if(System.Diagnostics.Debugger.IsAttached)
            System.Diagnostics.Debugger.Break();
    }

Then add a call to it in your code.