On Saturday, 30 August 2014 at 14:27:04 UTC, Nordlöw wrote:
I just noticed that AA rehash is @system. Is there a reason for this? Is it system because bad things can happen or simply because it's a low level function? Should I always tag functions calling rehash as @trusted?
AFAIK, the whole problem is one of attributes, and run-time inference.
AA's are mostly run-time implemented. When you have a U[T], and you want to rehash, then the AA will make a run-time call to typeinfo(T).hash();
The issue is that here, you need to support *all* of the hash function for *all* of the T types.
If you make rehash @trusted, then you may end up calling @system hash functions in a @safe context.
If you make it @safe, then you either break code, or make it impossible for end users to provide their @system hash functions.
Really, it's lose-lose. The only (AFAIK) solution is to migrate AA's to a template-library that individually infers the correct safety for every types.
