Produce specialized conformances to AnyObject for bound generic types.

Fixes rdar://31910351 (SR-4750)

Author: swiftix

lib/AST/ProtocolConformance.cpp

@@ -159,7 +159,13 @@ ProtocolConformanceRef::subst(Type origType,
     SmallVector<ProtocolConformance *, 1> lookupResults;
     classDecl->lookupConformance(classDecl->getParentModule(), proto,
                                  lookupResults);
-    return ProtocolConformanceRef(lookupResults.front());
+    auto *conf = lookupResults.front();
+    auto subMap = substType->getContextSubstitutionMap(
+        conf->getDeclContext()->getParentModule(), conf->getDeclContext());
+    if (!subMap.empty())
+      conf = substType->getASTContext().getSpecializedConformance(substType,
+                                                                  conf, subMap);
+    return ProtocolConformanceRef(conf);
   }
 
   llvm_unreachable("Invalid conformance substitution");

lib/AST/SubstitutionMap.cpp

@@ -116,7 +116,9 @@ Type SubstitutionMap::lookupSubstitution(CanSubstitutableType type) const {
   auto genericParam = cast<GenericTypeParamType>(type);
   auto mutableThis = const_cast<SubstitutionMap *>(this);
   auto replacementTypes = mutableThis->getReplacementTypes();
-  auto genericParams = getGenericSignature()->getGenericParams();
+  auto genericSig = getGenericSignature();
+  assert(genericSig);
+  auto genericParams = genericSig->getGenericParams();
   auto replacementIndex =
     GenericParamKey(genericParam).findIndexIn(genericParams);
 
@@ -133,7 +135,6 @@ Type SubstitutionMap::lookupSubstitution(CanSubstitutableType type) const {
   // The generic parameter may have been made concrete by the generic signature,
   // substitute into the concrete type.
   ModuleDecl &anyModule = *genericParam->getASTContext().getStdlibModule();
-  auto genericSig = getGenericSignature();
   if (auto concreteType = genericSig->getConcreteType(genericParam, anyModule)){
     // Set the replacement type to an error, to block infinite recursion.
     replacementType = ErrorType::get(concreteType);