Determine possibility to sort via hasmethod(isless, (T,T) for AbstractVector{T}

[tkf]

I was asking exactly the same question a few weeks ago

Can I use hasmethod inside @generated function?

I thought the answer was no, since hasmethod is not pure. But unless I try very hard to break it (see struct B example below) I cannot invoke any suspicious bugs. From the example I wrote, it seems that using hasmethod inside @generated function is OK as long as the method checked by hasmethod is already defined before the first invocation of the method. Is it correct? Are there any other pitfalls? Am I relying on some implementation details of julia which can change in the future? To avoi…