swift

ba908616 - Sema: Try a little harder to infer associated types to generic parameters if all else fails

Sema: Try a little harder to infer associated types to generic parameters if all else fails If we have an abstract witness, we don't attempt a generic parameter binding at all. But if simplifying the abstract witness failed, we should still attempt it. This would be cleaner as a disjunction in the solver but I want to change behavior as little as possible, so this adds a new fallback that we run when all else fails. Fixes rdar://problem/123345520.