Re: [C++ Patch / RFC] Change DERIVED_FROM_P to use tf_none?!?

[Jason Merrill]

Hmm, I suppose this could still end up doing unnecessary completions if 
both types are incomplete.  What happens if X is also incomplete?

The version that returns false if either is incomplete would give the 
wrong answer if the types are the same.

I think a better way would be to use COMPARE_STRICT if either type is 
incomplete.

Jason