swift

244d2afe - RequirementMachine: New way of propagating failure when building rewrite system for protocol

RequirementMachine: New way of propagating failure when building rewrite system for protocol If we failed to construct a rewrite system for a protocol, either because the Knuth-Bendix algorithm failed or because of a request cycle while resolving requirements, we would end up in a situation where the resulting rewrite system didn't include all conformance requirements and associated types, so name lookup would find declarations whose interface types are not valid type parameters. Fix this by propagating failure better and just doing nothing in getReducedTypeParameter(). Fixes rdar://147277543.