Why Does Dscanner Warn About a Missing toHash if opEquals is Defined?

[BLM768 via Digitalmars-d-learn]

On Sunday, 31 July 2016 at 18:57:50 UTC, Jack Stouffer wrote:
> Next question: what's the fastest hashing implementation that 
> will provide the least collisions? Is there a hash 
> implementation that's perfered for AAs?

I've heard that FNV-1a is a decent general-purpose option, and 
it's fairly straightforward.

https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function