I encountered a problem while trying to change the less template parameter of the setIntersection function in std.algorithm.  I finally distilled the problem down to a simple example.

<code>
#!/usr/bin/env rdmd

import std.stdio;

struct Test(alias less)
{
public:
   void doit()
   {
      less(1, 2);
   }
}

void main()
{
   int x = 5;
   auto f = delegate bool(int a, int b){ writefln("%s %s %s", x, a, b); return a < b; };

   auto d = Test!(f)();
   d.doit();
}
</code>

In this case, I should see output of "5 1 2", but instead I get a runtime error:

./test.d(10): Error: function test.main.Test!(f).Test.doit cannot access frame of function main
./test.d(19): Error: template instance test.main.Test!(f) error instantiating

If I remove the unneeded "public:" access modifier, the test works as expected.  I'm using dmd v2.047 for Mac OS X downloaded from digitalmars.com.

This seems related to the post from Andrei to the d-announce mailing list back in 07-Mar-2009 (http://www.mail-archive.com/digitalmars-d-announce@puremagic.com/msg01332.html).