SIL: Remove call to old form of getOpenedExistentialSignature()

Author: slavapestov

lib/SILOptimizer/Utils/Existential.cpp

@@ -12,6 +12,7 @@
 
 #include "swift/SILOptimizer/Utils/Existential.h"
 #include "swift/AST/ConformanceLookup.h"
+#include "swift/AST/LocalArchetypeRequirementCollector.h"
 #include "swift/AST/ProtocolConformance.h"
 #include "swift/Basic/Assertions.h"
 #include "swift/SIL/BasicBlockUtils.h"
@@ -250,15 +251,20 @@ void ConcreteExistentialInfo::initializeSubstitutionMap(
   // Construct a single-generic-parameter substitution map directly to the
   // ConcreteType with this existential's full list of conformances.
   //
-  // NOTE: getOpenedExistentialSignature() generates the signature for passing an
+  // NOTE: LocalArchetypeRequirementCollector generates the signature for passing an
   // opened existential as a generic parameter. No opened archetypes are
   // actually involved here--the API is only used as a convenient way to create
   // a substitution map. Since opened archetypes have different conformances
   // than their corresponding existential, ExistentialConformances needs to be
   // filtered when using it with this (phony) generic signature.
-  CanGenericSignature ExistentialSig =
-      M->getASTContext().getOpenedExistentialSignature(ExistentialType,
-                                                       GenericSignature());
+
+  auto &ctx = M->getASTContext();
+  LocalArchetypeRequirementCollector collector(ctx, CanGenericSignature());
+  collector.addOpenedExistential(ExistentialType);
+  auto ExistentialSig = buildGenericSignature(
+      ctx, collector.OuterSig, collector.Params, collector.Requirements,
+      /*allowInverses=*/true).getCanonicalSignature();
+
   ExistentialSubs = SubstitutionMap::get(
       ExistentialSig, [&](SubstitutableType *type) { return ConcreteType; },
       [&](CanType /*depType*/, Type /*replaceType*/,