November 22, 2007
ulong foo(ulong n) {
  if (n % 2 == 1)
    return n;
}
void main() {}

On DMD v1.023, gives:

Internal error: ..\ztc\cod2.c 411
November 23, 2007
bearophile wrote:
> On DMD v1.023, gives:
> 
> Internal error: ..\ztc\cod2.c 411

Works for me, no error (Win XP, DMD 1.023)