RequirementMachine: Actually compute the inherited protocol transitive closure

Author: slavapestov

lib/AST/RequirementMachine/ProtocolGraph.cpp

@@ -132,7 +132,7 @@ void ProtocolGraph::computeInheritedAssociatedTypes() {
 void ProtocolGraph::computeInheritedProtocols() {
   // Visit protocols in reverse order, so that if P inherits from Q and
   // Q inherits from R, we first visit R, then Q, then P, ensuring that
-  // R's associated types are added to P's list, etc.
+  // R's inherited protocols are added to P's list, etc.
   for (const auto *proto : llvm::reverse(Protocols)) {
     auto &info = Info[proto];
 

lib/AST/RequirementMachine/RequirementMachine.cpp

@@ -85,6 +85,7 @@ void RewriteSystemBuilder::addGenericSignature(CanGenericSignature sig) {
   Protocols.visitRequirements(sig->getRequirements());
   Protocols.computeTransitiveClosure();
   Protocols.computeLinearOrder();
+  Protocols.computeInheritedProtocols();
   Protocols.computeInheritedAssociatedTypes();
 
   // Add rewrite rules for each protocol.