opCast using in template struct

[bearophile]

Timon Gehr:

> What situations?

This thread has already shown two possible cases worth discussing 
about.

This report shows two more cases:
http://d.puremagic.com/issues/show_bug.cgi?id=8844

Two more cases:

Foo opBinary(string op="/\")(Foo f) {}
Foo opBinary(string op)(Foo f) if (op == "@") {}

And several other situations.

Bye,
bearophile