RequirementMachine: Concrete contraction gives up on recursive same-type and superclass requirements
RequirementMachine: Concrete contraction gives up on recursive same-type and superclass requirements

A requirement of the form T == G<T> is never valid, and T == G<T.A>
will leave behind a term T.[P:A] once the conformance T : P is
dropped in contraction. So just ignore recursive requirements
here, allowing them to be properly diagnosed later.

glessard/swift,benlangmuir/swift,apple/swift,roambotics/swift,benlangmuir/swift,benlangmuir/swift,glessard/swift,benlangmuir/swift,benlangmuir/swift,glessard/swift,benlangmuir/swift,roambotics/swift,roambotics/swift,apple/swift,roambotics/swift,glessard/swift,apple/swift,roambotics/swift,glessard/swift,apple/swift,apple/swift,roambotics/swift,glessard/swift,apple/swift