RequirementMachine: Tweak debug output and add an assertion

Author: slavapestov

lib/AST/RequirementMachine/ConcreteContraction.cpp

@@ -531,6 +531,12 @@ bool ConcreteContraction::performConcreteContraction(
   // Phase 2: Replace each concretely-conforming generic parameter with its
   // concrete type.
   for (auto req : requirements) {
+    if (Debug) {
+      llvm::dbgs() << "@ Original requirement: ";
+      req.req.dump(llvm::dbgs());
+      llvm::dbgs() << "\n";
+    }
+
     // Substitute the requirement.
     Optional<Requirement> substReq = substRequirement(req.req);
 

lib/AST/RequirementMachine/ConcreteTypeWitness.cpp

@@ -200,7 +200,9 @@ void PropertyMap::concretizeTypeWitnessInConformance(
     AssociatedTypeDecl *assocType) const {
   auto concreteType = concreteConformanceSymbol.getConcreteType();
   auto substitutions = concreteConformanceSymbol.getSubstitutions();
-  auto *proto = concreteConformanceSymbol.getProtocol();
+
+  auto *proto = assocType->getProtocol();
+  assert(proto == concreteConformanceSymbol.getProtocol());
 
   if (Debug.contains(DebugFlags::ConcretizeNestedTypes)) {
     llvm::dbgs() << "^^ " << "Looking up type witness for "

lib/AST/RequirementMachine/RequirementLowering.cpp

@@ -1416,7 +1416,7 @@ void RuleBuilder::collectRulesFromReferencedProtocols() {
     // if neccessary, which will cause us to re-enter into a new RuleBuilder
     // instace under RuleBuilder::initWithProtocolWrittenRequirements().
     if (Dump) {
-      llvm::dbgs() << "importing protocol " << proto->getName() << " {\n";
+      llvm::dbgs() << "importing protocol " << proto->getName() << "\n";
     }
 
     auto *machine = Context.getRequirementMachine(proto);