[pmalynin]

In general this isn’t true (i guess it is in this specific context). For example I believe it’s totally expected to specialize std hash

[tyleo]

I’ve also done this with hash… though given the footguns scattered about, I wouldn’t be surprised if it broke the spec.

[Conscat]

That is a completely intended way to use std::hash, along with a few other functions like std::tuple_size and std::tuple_element.