The documentation http://www.digitalmars.com/d/2.0/arrays.html writes that "For the .sort property to work on arrays of structs or unions, the struct or union definition must define the function: int opCmp(S) or int opCmp(S*)". That is misleading, as, in my experience, a struct must implement exactly "int opCmp(ref const S) const" in order to get .sort work. Signatures which are a bit different do not work.

The documentation should be updated as soon as possible, either informing the programmer about a current bug in the compiler, or clearly stating that only this signature works! In addition, I think that the compiler should warn about using a likely incorrect signature.