Allow type variables to appear inside opened existential archetypes

include/swift/AST/ASTContext.h

@@ -1446,19 +1446,6 @@ class ASTContext final {
   /// like `<T>`.
   CanGenericSignature getSingleGenericParameterSignature() const;
 
-  /// Retrieve a generic signature with a single type parameter conforming
-  /// to the given protocol or composition type, like <T: P>.
-  ///
-  /// The opened archetype may have a different set of conformances from the
-  /// corresponding existential. The opened archetype conformances are dictated
-  /// by the ABI for generic arguments, while the existential value conformances
-  /// are dictated by their layout (see \c Type::getExistentialLayout()). In
-  /// particular, the opened archetype signature does not have requirements for
-  /// conformances inherited from superclass constraints while existential
-  /// values do.
-  CanGenericSignature getOpenedExistentialSignature(Type type,
-                                                    GenericSignature parentSig);
-
   /// Retrieve a generic signature with a single type parameter conforming
   /// to the given protocol or composition type, like <T: P>.
   ///

include/swift/AST/TypeTransform.h

@@ -18,6 +18,7 @@
 #ifndef SWIFT_AST_TYPETRANSFORM_H
 #define SWIFT_AST_TYPETRANSFORM_H
 
+#include "swift/AST/GenericEnvironment.h"
 #include "swift/AST/SILLayout.h"
 
 namespace swift {
@@ -136,7 +137,29 @@ case TypeKind::Id:
                                           newSubMap);
     }
 
-    case TypeKind::OpenedArchetype:
+    case TypeKind::OpenedArchetype: {
+      auto *local = cast<LocalArchetypeType>(base);
+      if (auto result = asDerived().transformLocalArchetypeType(local, pos))
+        return *result;
+
+      auto *env = local->getGenericEnvironment();
+
+      auto genericSig = env->getGenericSignature();
+      auto existentialTy = env->getOpenedExistentialType();
+      auto subMap = env->getOuterSubstitutions();
+      auto uuid = env->getOpenedExistentialUUID();
+
+      auto newSubMap = asDerived().transformSubMap(subMap);
+      if (newSubMap == subMap)
+        return t;
+      if (!newSubMap)
+        return Type();
+
+      auto *newEnv = GenericEnvironment::forOpenedExistential(
+          genericSig, existentialTy, newSubMap, uuid);
+      return newEnv->mapTypeIntoContext(local->getInterfaceType());
+    }
+
     case TypeKind::ElementArchetype: {
       auto *local = cast<LocalArchetypeType>(base);
       if (auto result = asDerived().transformLocalArchetypeType(local, pos))

include/swift/AST/Types.h

@@ -6785,15 +6785,6 @@ class OpenedArchetypeType final : public LocalArchetypeType,
          ArrayRef<ProtocolDecl *> conformsTo, Type superclass,
          LayoutConstraint layout);
 
-public:
-  /// Compute the parameter that serves as the \c Self type for an opened
-  /// archetype from the given outer generic signature.
-  ///
-  /// This type is a generic parameter one level deeper
-  /// than the deepest generic context depth.
-  static Type getSelfInterfaceTypeFromContext(GenericSignature parentSig,
-                                              ASTContext &ctx);
-
 public:
   /// Get or create an archetype that represents the opened type
   /// of an existential value.
@@ -6814,9 +6805,6 @@ class OpenedArchetypeType final : public LocalArchetypeType,
   /// \param existential The existential type or existential metatype to open.
   static Type getAny(Type existential);
 
-  /// Retrieve the ID number of this opened existential.
-  UUID getOpenedExistentialID() const;
-
   static bool classof(const TypeBase *T) {
     return T->getKind() == TypeKind::OpenedArchetype;
   }

include/swift/SIL/SILCloner.h

@@ -245,8 +245,8 @@ class SILCloner : protected SILInstructionVisitor<ImplClass> {
   /// Register a re-mapping for local archetypes such as opened existentials.
   void registerLocalArchetypeRemapping(GenericEnvironment *From,
                                        GenericEnvironment *To) {
-    ASSERT(From->getGenericSignature()->getMaxDepth()
-           == To->getGenericSignature()->getMaxDepth());
+    ASSERT(From->getGenericSignature().getPointer()
+           == To->getGenericSignature().getPointer());
 
     auto result = Functor.LocalArchetypeSubs.insert(std::make_pair(From, To));
     assert(result.second);
@@ -380,14 +380,14 @@ class SILCloner : protected SILInstructionVisitor<ImplClass> {
 
   void remapRootOpenedType(CanOpenedArchetypeType archetypeTy) {
     auto *origEnv = archetypeTy->getGenericEnvironment();
+
+    auto genericSig = origEnv->getGenericSignature();
+    auto existentialTy = origEnv->getOpenedExistentialType();
     auto subMap = origEnv->getOuterSubstitutions();
-    ASSERT(!subMap && "Transform the substitution map!");
-    auto origExistentialTy = origEnv->getOpenedExistentialType()
-        ->getCanonicalType();
 
-    auto substExistentialTy = getOpASTType(origExistentialTy);
     auto *newEnv = GenericEnvironment::forOpenedExistential(
-        substExistentialTy, UUID::fromTime());
+        genericSig, existentialTy, getOpSubstitutionMap(subMap),
+        UUID::fromTime());
 
     registerLocalArchetypeRemapping(origEnv, newEnv);
   }
@@ -2675,7 +2675,7 @@ template<typename ImplClass>
 void
 SILCloner<ImplClass>::visitOpenExistentialAddrInst(OpenExistentialAddrInst *Inst) {
   // Create a new archetype for this opened existential type.
-  remapRootOpenedType(Inst->getType().castTo<OpenedArchetypeType>());
+  remapRootOpenedType(Inst->getDefinedOpenedArchetype());
 
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   recordClonedInstruction(
@@ -2688,7 +2688,7 @@ template <typename ImplClass>
 void SILCloner<ImplClass>::visitOpenExistentialValueInst(
     OpenExistentialValueInst *Inst) {
   // Create a new archetype for this opened existential type.
-  remapRootOpenedType(Inst->getType().castTo<OpenedArchetypeType>());
+  remapRootOpenedType(Inst->getDefinedOpenedArchetype());
 
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   recordClonedInstruction(
@@ -2704,14 +2704,7 @@ template<typename ImplClass>
 void
 SILCloner<ImplClass>::
 visitOpenExistentialMetatypeInst(OpenExistentialMetatypeInst *Inst) {
-  // Create a new archetype for this opened existential type.
-  auto openedType = Inst->getType().getASTType();
-  auto exType = Inst->getOperand()->getType().getASTType();
-  while (auto exMetatype = dyn_cast<ExistentialMetatypeType>(exType)) {
-    exType = exMetatype->getExistentialInstanceType()->getCanonicalType();
-    openedType = cast<MetatypeType>(openedType).getInstanceType();
-  }
-  remapRootOpenedType(cast<OpenedArchetypeType>(openedType));
+  remapRootOpenedType(Inst->getDefinedOpenedArchetype());
 
   if (!Inst->getOperand()->getType().canUseExistentialRepresentation(
           ExistentialRepresentation::Class)) {
@@ -2735,7 +2728,7 @@ void
 SILCloner<ImplClass>::
 visitOpenExistentialRefInst(OpenExistentialRefInst *Inst) {
   // Create a new archetype for this opened existential type.
-  remapRootOpenedType(Inst->getType().castTo<OpenedArchetypeType>());
+  remapRootOpenedType(Inst->getDefinedOpenedArchetype());
 
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   recordClonedInstruction(
@@ -2752,7 +2745,7 @@ void
 SILCloner<ImplClass>::
 visitOpenExistentialBoxInst(OpenExistentialBoxInst *Inst) {
   // Create a new archetype for this opened existential type.
-  remapRootOpenedType(Inst->getType().castTo<OpenedArchetypeType>());
+  remapRootOpenedType(Inst->getDefinedOpenedArchetype());
 
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   recordClonedInstruction(Inst, getBuilder().createOpenExistentialBox(
@@ -2766,7 +2759,7 @@ void
 SILCloner<ImplClass>::
 visitOpenExistentialBoxValueInst(OpenExistentialBoxValueInst *Inst) {
   // Create a new archetype for this opened existential type.
-  remapRootOpenedType(Inst->getType().castTo<OpenedArchetypeType>());
+  remapRootOpenedType(Inst->getDefinedOpenedArchetype());
 
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   recordClonedInstruction(

lib/AST/ASTContext.cpp

@@ -457,10 +457,6 @@ struct ASTContext::Implementation {
   /// The single-parameter generic signature with no constraints, <T>.
   CanGenericSignature SingleGenericParameterSignature;
 
-  /// The existential signature <T : P> for each P.
-  llvm::DenseMap<std::pair<CanType, const GenericSignatureImpl *>, CanGenericSignature>
-      ExistentialSignatures;
-
   /// The element signature for a generic signature, which contains a clone
   /// of the context generic signature with new type parameters and requirements
   /// for opened pack elements in the given shape equivalence class.
@@ -851,7 +847,6 @@ void ASTContext::Implementation::dump(llvm::raw_ostream &os) const {
   SIZE_AND_BYTES(AssociativityCache);
   SIZE_AND_BYTES(DelayedConformanceDiags);
   SIZE_AND_BYTES(LazyContexts);
-  SIZE_AND_BYTES(ExistentialSignatures);
   SIZE_AND_BYTES(ElementSignatures);
   SIZE_AND_BYTES(Overrides);
   SIZE_AND_BYTES(DefaultWitnesses);
@@ -5342,22 +5337,21 @@ CanTypeWrapper<OpenedArchetypeType> OpenedArchetypeType::getNew(
 
 CanOpenedArchetypeType OpenedArchetypeType::get(CanType existential,
                                                 std::optional<UUID> knownID) {
-  assert(existential->isExistentialType());
-  assert(!existential->hasTypeParameter());
-
-  auto interfaceType = OpenedArchetypeType::getSelfInterfaceTypeFromContext(
-      GenericSignature(), existential->getASTContext());
+  auto &ctx = existential->getASTContext();
+  auto existentialSig = ctx.getOpenedExistentialSignature(existential);
 
   if (!knownID)
     knownID = UUID::fromTime();
 
   auto *genericEnv = GenericEnvironment::forOpenedExistential(
-      existential, *knownID);
+      existentialSig.OpenedSig,
+      existentialSig.Shape,
+      existentialSig.Generalization,
+      *knownID);
 
-  // Map the interface type into that environment.
-  auto result = genericEnv->mapTypeIntoContext(interfaceType)
-      ->castTo<OpenedArchetypeType>();
-  return CanOpenedArchetypeType(result);
+  return cast<OpenedArchetypeType>(
+    genericEnv->mapTypeIntoContext(existentialSig.SelfType)
+      ->getCanonicalType());
 }
 
 Type OpenedArchetypeType::getAny(Type existential) {
@@ -5547,8 +5541,10 @@ GenericEnvironment *GenericEnvironment::forOpaqueType(
 GenericEnvironment *
 GenericEnvironment::forOpenedExistential(Type existential, UUID uuid) {
   auto &ctx = existential->getASTContext();
-  auto signature = ctx.getOpenedExistentialSignature(existential, GenericSignature());
-  return forOpenedExistential(signature, existential, SubstitutionMap(), uuid);
+  auto existentialSig = ctx.getOpenedExistentialSignature(existential);
+  return forOpenedExistential(existentialSig.OpenedSig,
+                              existentialSig.Shape,
+                              existentialSig.Generalization, uuid);
 }
 
 /// Create a new generic environment for an opened archetype.
@@ -6136,83 +6132,51 @@ CanGenericSignature ASTContext::getSingleGenericParameterSignature() const {
   return canonicalSig;
 }
 
-Type OpenedArchetypeType::getSelfInterfaceTypeFromContext(GenericSignature parentSig,
-                                                          ASTContext &ctx) {
-  return GenericTypeParamType::get(/*isParameterPack=*/ false,
-                                   parentSig.getNextDepth(), /*index=*/ 0,
-                                   ctx);
-}
-
-CanGenericSignature
-ASTContext::getOpenedExistentialSignature(Type type, GenericSignature parentSig) {
-  assert(type->isExistentialType());
-
-  if (auto existential = type->getAs<ExistentialType>())
-    type = existential->getConstraintType();
-
-  const CanType constraint = type->getCanonicalType();
-
-  auto canParentSig = parentSig.getCanonicalSignature();
-  auto key = std::make_pair(constraint, canParentSig.getPointer());
-  auto found = getImpl().ExistentialSignatures.find(key);
-  if (found != getImpl().ExistentialSignatures.end())
-    return found->second;
-
-  LocalArchetypeRequirementCollector collector(*this, canParentSig);
-  collector.addOpenedExistential(type);
-  auto genericSig = buildGenericSignature(
-      *this, collector.OuterSig, collector.Params, collector.Requirements,
-      /*allowInverses=*/true).getCanonicalSignature();
-
-  auto result = getImpl().ExistentialSignatures.insert(
-      std::make_pair(key, genericSig));
-  ASSERT(result.second);
-
-  return genericSig;
-}
-
 OpenedExistentialSignature
 ASTContext::getOpenedExistentialSignature(Type type) {
   assert(type->isExistentialType());
 
-  if (auto existential = type->getAs<ExistentialType>())
-    type = existential->getConstraintType();
-
-  const CanType constraint = type->getCanonicalType();
+  auto canType = type->getCanonicalType();
 
   // The constraint type might contain type variables.
-  auto properties = constraint->getRecursiveProperties();
+  auto properties = canType->getRecursiveProperties();
   auto arena = getArena(properties);
 
   // Check the cache.
   const auto &sigs = getImpl().getArena(arena).ExistentialSignatures;
-  auto found = sigs.find(constraint);
+  auto found = sigs.find(canType);
   if (found != sigs.end())
     return found->second;
 
   OpenedExistentialSignature existentialSig;
 
   // Generalize the existential type, to move type variables and primary
   // archetypes into the substitution map.
-  auto gen = ExistentialTypeGeneralization::get(constraint);
+  auto gen = ExistentialTypeGeneralization::get(canType);
+
   existentialSig.Shape = gen.Shape->getCanonicalType();
   existentialSig.Generalization = gen.Generalization;
 
   // Now, we have an existential type written with type parameters only.
   // Open the generalization signature by adding a new generic parameter
   // for `Self`.
   auto parentSig = gen.Generalization.getGenericSignature();
-  existentialSig.OpenedSig =
-      getOpenedExistentialSignature(gen.Shape, parentSig);
+  auto canParentSig = parentSig.getCanonicalSignature();
+
+  LocalArchetypeRequirementCollector collector(*this, canParentSig);
+  collector.addOpenedExistential(gen.Shape);
+  existentialSig.OpenedSig = buildGenericSignature(
+      *this, collector.OuterSig, collector.Params, collector.Requirements,
+      /*allowInverses=*/true).getCanonicalSignature();
 
   // Stash the `Self` type.
   existentialSig.SelfType =
-      OpenedArchetypeType::getSelfInterfaceTypeFromContext(parentSig, *this)
+      existentialSig.OpenedSig.getGenericParams().back()
           ->getCanonicalType();
 
   // Cache the result.
   auto result = getImpl().getArena(arena).ExistentialSignatures.insert(
-      std::make_pair(constraint, existentialSig));
+      std::make_pair(canType, existentialSig));
   ASSERT(result.second);
 
   return existentialSig;

lib/AST/ASTDumper.cpp

@@ -4219,10 +4219,13 @@ namespace {
     void visitOpenedArchetypeType(OpenedArchetypeType *T, StringRef label) {
       printArchetypeCommon(T, "opened_archetype_type", label);
 
-      printFieldQuoted(T->getOpenedExistentialID(), "opened_existential_id");
+      auto *env = T->getGenericEnvironment();
+      printFieldQuoted(env->getOpenedExistentialUUID(), "opened_existential_id");
 
       printArchetypeCommonRec(T);
-      printRec(T->getGenericEnvironment()->getOpenedExistentialType(), "opened_existential");
+      printRec(env->getOpenedExistentialType(), "opened_existential");
+      if (auto subMap = env->getOuterSubstitutions())
+        printRec(subMap, "substitutions");
 
       printFoot();
     }

lib/AST/ASTPrinter.cpp

@@ -6967,8 +6967,12 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
 
   void visitOpenedArchetypeType(OpenedArchetypeType *T) {
     if (Options.PrintForSIL) {
-      Printer << "@opened(\"" << T->getOpenedExistentialID() << "\", ";
-      visit(T->getGenericEnvironment()->getOpenedExistentialType());
+      auto *env = T->getGenericEnvironment();
+
+      Printer << "@opened(\"" << env->getOpenedExistentialUUID() << "\", ";
+      auto existentialTy = env->maybeApplyOuterContextSubstitutions(
+          env->getOpenedExistentialType());
+      visit(existentialTy);
       Printer << ") ";
 
       llvm::DenseMap<CanType, Identifier> newAlternativeTypeNames;