Merge pull request #61942 from slavapestov/archetype-existential-type-fixes

More accurate ArchetypeType::getExistentialType()

Author: slavapestov

include/swift/AST/Decl.h

@@ -4721,7 +4721,7 @@ class ProtocolDecl final : public NominalTypeDecl {
   AssociatedTypeDecl *getAssociatedType(Identifier name) const;
 
   /// Returns the existential type for this protocol.
-  Type getExistentialType() const {
+  Type getDeclaredExistentialType() const {
     return ExistentialType::get(getDeclaredInterfaceType());
   }
 

include/swift/AST/GenericSignature.h

@@ -457,6 +457,13 @@ class alignas(1 << TypeAlignInBits) GenericSignatureImpl final
   /// will return an instance of \c ExistentialType.
   Type getNonDependentUpperBounds(Type type) const;
 
+  /// Given a type parameter, compute the most specific supertype (upper bound)
+  /// that is possibly dependent on other type parameters.
+  ///
+  /// \note If the upper bound is a protocol or protocol composition,
+  /// will return an instance of \c ExistentialType.
+  Type getDependentUpperBounds(Type type) const;
+
   static void Profile(llvm::FoldingSetNodeID &ID,
                       TypeArrayView<GenericTypeParamType> genericParams,
                       ArrayRef<Requirement> requirements);

include/swift/AST/Types.h

@@ -6689,17 +6689,6 @@ inline bool TypeBase::isOpenedExistential() const {
   return isa<OpenedArchetypeType>(T);
 }
 
-inline bool TypeBase::isOpenedExistentialWithError() {
-  if (!hasOpenedExistential())
-    return false;
-
-  CanType T = getCanonicalType();
-  if (auto archetype = dyn_cast<OpenedArchetypeType>(T)) {
-    return archetype->getExistentialType()->isExistentialWithError();
-  }
-  return false;
-}
-
 inline bool TypeBase::canDynamicallyBeOptionalType(bool includeExistential) {
   CanType T = getCanonicalType();
   auto isArchetypeOrExistential = isa<ArchetypeType>(T) ||

lib/AST/ASTContext.cpp

@@ -930,8 +930,8 @@ Type ASTContext::get##NAME##Type() const { \
 #include "swift/AST/KnownStdlibTypes.def"
 
 CanType ASTContext::getErrorExistentialType() const {
-  if (auto exn = getErrorDecl()) {
-    return exn->getExistentialType()->getCanonicalType();
+  if (auto *errorProto = getErrorDecl()) {
+    return errorProto->getDeclaredExistentialType()->getCanonicalType();
   } else {
     // Use Builtin.NativeObject just as a stand-in.
     return TheNativeObjectType;
@@ -2605,7 +2605,7 @@ ASTContext::getSelfConformance(ProtocolDecl *protocol) {
   auto &entry = selfConformances[protocol];
   if (!entry) {
     entry = new (*this, AllocationArena::Permanent)
-      SelfProtocolConformance(protocol->getExistentialType());
+      SelfProtocolConformance(protocol->getDeclaredExistentialType());
   }
   return entry;
 }

lib/AST/ASTPrinter.cpp

@@ -6473,6 +6473,13 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
       if (auto existential = constraint->getAs<ExistentialType>())
         constraint = existential->getConstraintType();
 
+      // Opaque archetype substitutions are always canonical, so re-sugar the
+      // constraint type using the owning declaration's generic parameter names.
+      auto genericSig = T->getDecl()->getNamingDecl()->getInnermostDeclContext()
+          ->getGenericSignatureOfContext();
+      if (genericSig)
+        constraint = genericSig->getSugaredType(constraint);
+
       visit(constraint);
       return;
     }

lib/AST/GenericSignature.cpp

@@ -598,6 +598,8 @@ unsigned GenericSignatureImpl::getGenericParamOrdinal(
 Type GenericSignatureImpl::getNonDependentUpperBounds(Type type) const {
   assert(type->isTypeParameter());
 
+  bool hasExplicitAnyObject = requiresClass(type);
+
   llvm::SmallVector<Type, 2> types;
   if (Type superclass = getSuperclassBound(type)) {
     // If the class contains a type parameter, try looking for a non-dependent
@@ -606,24 +608,119 @@ Type GenericSignatureImpl::getNonDependentUpperBounds(Type type) const {
       superclass = superclass->getSuperclass();
     }
 
-    if (superclass)
+    if (superclass) {
       types.push_back(superclass);
+      hasExplicitAnyObject = false;
+    }
   }
-  for (const auto &elt : getRequiredProtocols(type)) {
-    types.push_back(elt->getDeclaredInterfaceType());
+  for (auto *proto : getRequiredProtocols(type)) {
+    if (proto->requiresClass())
+      hasExplicitAnyObject = false;
+
+    types.push_back(proto->getDeclaredInterfaceType());
   }
 
-  const auto layout = getLayoutConstraint(type);
-  const auto boundsTy = ProtocolCompositionType::get(
+  auto constraint = ProtocolCompositionType::get(
       getASTContext(), types,
-      /*HasExplicitAnyObject=*/layout &&
-          layout->getKind() == LayoutConstraintKind::Class);
+      hasExplicitAnyObject);
+
+  if (!constraint->isConstraintType()) {
+    assert(constraint->getClassOrBoundGenericClass());
+    return constraint;
+  }
+
+  return ExistentialType::get(constraint);
+}
+
+Type GenericSignatureImpl::getDependentUpperBounds(Type type) const {
+  assert(type->isTypeParameter());
+
+  llvm::SmallVector<Type, 2> types;
+
+  auto &ctx = type->getASTContext();
+
+  bool hasExplicitAnyObject = requiresClass(type);
+
+  // FIXME: If the superclass bound is implied by one of our protocols, we
+  // shouldn't add it to the constraint type.
+  if (Type superclass = getSuperclassBound(type)) {
+    types.push_back(superclass);
+    hasExplicitAnyObject = false;
+  }
+
+  for (auto proto : getRequiredProtocols(type)) {
+    if (proto->requiresClass())
+      hasExplicitAnyObject = false;
+
+    auto *baseType = proto->getDeclaredInterfaceType()->castTo<ProtocolType>();
+
+    auto primaryAssocTypes = proto->getPrimaryAssociatedTypes();
+    if (!primaryAssocTypes.empty()) {
+      SmallVector<Type, 2> argTypes;
+
+      // Attempt to recover same-type requirements on primary associated types.
+      for (auto *assocType : primaryAssocTypes) {
+        // For each primary associated type A of P, compute the reduced type
+        // of T.[P]A.
+        auto *memberType = DependentMemberType::get(type, assocType);
+        auto reducedType = getReducedType(memberType);
+
+        // If the reduced type is at a lower depth than the root generic
+        // parameter of T, then it's constrained.
+        bool hasOuterGenericParam = false;
+        bool hasInnerGenericParam = false;
+        reducedType.visit([&](Type t) {
+          if (auto *paramTy = t->getAs<GenericTypeParamType>()) {
+            unsigned rootDepth = type->getRootGenericParam()->getDepth();
+            if (paramTy->getDepth() == rootDepth)
+              hasInnerGenericParam = true;
+            else {
+              assert(paramTy->getDepth() < rootDepth);
+              hasOuterGenericParam = true;
+            }
+          }
+        });
+
+        if (hasInnerGenericParam && hasOuterGenericParam) {
+          llvm::errs() << "Weird same-type requirements?\n";
+          llvm::errs() << "Interface type: " << type << "\n";
+          llvm::errs() << "Member type: " << memberType << "\n";
+          llvm::errs() << "Reduced member type: " << reducedType << "\n";
+          llvm::errs() << GenericSignature(this) << "\n";
+          abort();
+        }
+
+        if (!hasInnerGenericParam)
+          argTypes.push_back(reducedType);
+      }
+
+      // We should have either constrained all primary associated types,
+      // or none of them.
+      if (!argTypes.empty()) {
+        if (argTypes.size() != primaryAssocTypes.size()) {
+          llvm::errs() << "Not all primary associated types constrained?\n";
+          llvm::errs() << "Interface type: " << type << "\n";
+          llvm::errs() << GenericSignature(this) << "\n";
+          abort();
+        }
+
+        types.push_back(ParameterizedProtocolType::get(ctx, baseType, argTypes));
+        continue;
+      }
+    }
+
+    types.push_back(baseType);
+  }
+
+  auto constraint = ProtocolCompositionType::get(
+     ctx, types, hasExplicitAnyObject);
 
-  if (boundsTy->isExistentialType()) {
-    return ExistentialType::get(boundsTy);
+  if (!constraint->isConstraintType()) {
+    assert(constraint->getClassOrBoundGenericClass());
+    return constraint;
   }
 
-  return boundsTy;
+  return ExistentialType::get(constraint);
 }
 
 void GenericSignature::Profile(llvm::FoldingSetNodeID &id) const {

lib/AST/Type.cpp

@@ -1113,6 +1113,19 @@ bool TypeBase::isExistentialWithError() {
   return layout.isExistentialWithError(getASTContext());
 }
 
+bool TypeBase::isOpenedExistentialWithError() {
+  if (auto archetype = getAs<OpenedArchetypeType>()) {
+    auto errorProto = getASTContext().getErrorDecl();
+    if (!errorProto) return false;
+
+    for (auto protoDecl : archetype->getConformsTo()) {
+      if (protoDecl == errorProto || protoDecl->inheritsFrom(errorProto))
+        return true;
+    }
+  }
+  return false;
+}
+
 bool TypeBase::isStdlibType() {
   if (auto *NTD = getAnyNominal()) {
     auto *DC = NTD->getDeclContext();
@@ -3493,34 +3506,22 @@ bool ArchetypeType::isRoot() const {
 }
 
 Type ArchetypeType::getExistentialType() const {
+  auto *genericEnv = getGenericEnvironment();
+
   // Opened types hold this directly.
   if (auto *opened = dyn_cast<OpenedArchetypeType>(this)) {
     if (opened->isRoot()) {
-      return getGenericEnvironment()->getOpenedExistentialType();
+      return genericEnv->getOpenedExistentialType();
     }
   }
 
-  // Otherwise, compute it from scratch.
-  SmallVector<Type, 4> constraintTypes;
-  
-  if (auto super = getSuperclass()) {
-    constraintTypes.push_back(super);
-  }
-  for (auto proto : getConformsTo()) {
-    constraintTypes.push_back(proto->getDeclaredInterfaceType());
-  }
-  auto &ctx = const_cast<ArchetypeType*>(this)->getASTContext();
-  auto constraint = ProtocolCompositionType::get(
-     ctx, constraintTypes, requiresClass());
+  // Otherwise we compute it via a generic signature query.
+  auto interfaceType = getInterfaceType();
+  auto genericSig = genericEnv->getGenericSignature();
 
-  // If the archetype is only constrained to a class type,
-  // return the class type directly.
-  if (!constraint->isConstraintType()) {
-    assert(constraint->getClassOrBoundGenericClass());
-    return constraint;
-  }
+  auto upperBound = genericSig->getDependentUpperBounds(interfaceType);
 
-  return ExistentialType::get(constraint);
+  return genericEnv->mapTypeIntoContext(upperBound);
 }
 
 bool ArchetypeType::requiresClass() const {

lib/SILGen/SILGenType.cpp

@@ -866,7 +866,8 @@ static SILFunction *emitSelfConformanceWitness(SILGenModule &SGM,
 
   // Open the protocol type.
   auto openedType = OpenedArchetypeType::get(
-      protocol->getExistentialType()->getCanonicalType(), GenericSignature());
+      protocol->getDeclaredExistentialType()->getCanonicalType(),
+      GenericSignature());
 
   // Form the substitutions for calling the witness.
   auto witnessSubs = SubstitutionMap::getProtocolSubstitutions(protocol,

lib/Sema/CSApply.cpp

@@ -76,7 +76,8 @@ static bool isOpenedAnyObject(Type type) {
   if (!archetype || !archetype->isRoot())
     return false;
 
-  return archetype->getExistentialType()->isAnyObject();
+  return (archetype->requiresClass() &&
+          !archetype->hasRequirements());
 }
 
 SubstitutionMap

lib/Sema/CSSimplify.cpp

@@ -8118,7 +8118,7 @@ static bool isCastToExpressibleByNilLiteral(ConstraintSystem &cs, Type fromType,
   if (!nilLiteral)
     return false;
 
-  return toType->isEqual(nilLiteral->getExistentialType()) &&
+  return toType->isEqual(nilLiteral->getDeclaredExistentialType()) &&
          fromType->getOptionalObjectType();
 }
 

lib/Sema/TypeCheckType.cpp

@@ -647,8 +647,6 @@ bool TypeChecker::checkContextualRequirements(GenericTypeDecl *decl,
   llvm_unreachable("invalid requirement check type");
 }
 
-static void diagnoseUnboundGenericType(Type ty, SourceLoc loc);
-
 /// Apply generic arguments to the given type.
 ///
 /// If the type is itself not generic, this does nothing.
@@ -756,10 +754,11 @@ static Type applyGenericArguments(Type type, TypeResolution resolution,
     // Build ParameterizedProtocolType if the protocol has a primary associated
     // type and we're in a supported context (for now just generic requirements,
     // inheritance clause, extension binding).
-    if (resolution.getOptions().isConstraintImplicitExistential() && !ctx.LangOpts.hasFeature(Feature::ImplicitSome)) {
+    if (resolution.getOptions().isConstraintImplicitExistential() &&
+        !ctx.LangOpts.hasFeature(Feature::ImplicitSome)) {
       diags.diagnose(loc, diag::existential_requires_any,
                      protoDecl->getDeclaredInterfaceType(),
-                     protoDecl->getExistentialType(),
+                     protoDecl->getDeclaredExistentialType(),
                      /*isAlias=*/isa<TypeAliasType>(type.getPointer()));
 
       return ErrorType::get(ctx);
@@ -1700,7 +1699,7 @@ static Type resolveNestedIdentTypeComponent(TypeResolution resolution,
   auto DC = resolution.getDeclContext();
   auto &ctx = DC->getASTContext();
   auto &diags = ctx.Diags;
-  auto isExtenstionBinding = options.is(TypeResolverContext::ExtensionBinding);
+  auto isExtensionBinding = options.is(TypeResolverContext::ExtensionBinding);
 
   auto maybeDiagnoseBadMemberType = [&](TypeDecl *member, Type memberType,
                                         AssociatedTypeDecl *inferredAssocType) {
@@ -1715,13 +1714,13 @@ static Type resolveNestedIdentTypeComponent(TypeResolution resolution,
 
     if (options.contains(TypeResolutionFlags::SilenceErrors)) {
       if (TypeChecker::isUnsupportedMemberTypeAccess(
-              parentTy, member, hasUnboundOpener, isExtenstionBinding) !=
+              parentTy, member, hasUnboundOpener, isExtensionBinding) !=
           TypeChecker::UnsupportedMemberTypeAccessKind::None)
         return ErrorType::get(ctx);
     }
 
     switch (TypeChecker::isUnsupportedMemberTypeAccess(
-        parentTy, member, hasUnboundOpener, isExtenstionBinding)) {
+        parentTy, member, hasUnboundOpener, isExtensionBinding)) {
     case TypeChecker::UnsupportedMemberTypeAccessKind::None:
       break;
 
@@ -1910,7 +1909,9 @@ static Type applyNonEscapingIfNecessary(Type ty,
 
     // We lost the sugar to flip the isNoEscape bit.
     //
-    // FIXME(https://github.com/apple/swift/issues/45125): It would be better to add a new AttributedType sugared type, which would wrap the TypeAliasType or ParenType, and apply the isNoEscape bit when de-sugaring.
+    // FIXME(https://github.com/apple/swift/issues/45125): It would be better
+    // to add a new AttributedType sugared type, which would wrap the
+    // TypeAliasType and apply the isNoEscape bit when de-sugaring.
     return FunctionType::get(funcTy->getParams(), funcTy->getResult(), extInfo);
   }
 
@@ -2340,10 +2341,11 @@ NeverNullType TypeResolver::resolveType(TypeRepr *repr,
         return ty;
       };
 
-      if(getASTContext().LangOpts.hasFeature(Feature::ImplicitSome)){
+      if(getASTContext().LangOpts.hasFeature(Feature::ImplicitSome)) {
         if (auto opaqueDecl = dyn_cast<OpaqueTypeDecl>(DC)) {
           if (auto ordinal = opaqueDecl->getAnonymousOpaqueParamOrdinal(repr))
-            return diagnoseDisallowedExistential(getIdentityOpaqueTypeArchetypeType(opaqueDecl, *ordinal));
+            return diagnoseDisallowedExistential(
+                getIdentityOpaqueTypeArchetypeType(opaqueDecl, *ordinal));
         }
       }
 
@@ -4790,7 +4792,7 @@ class ExistentialTypeVisitor
         Ctx.Diags.diagnose(comp->getNameLoc(),
                            diag::existential_requires_any,
                            proto->getDeclaredInterfaceType(),
-                           proto->getExistentialType(),
+                           proto->getDeclaredExistentialType(),
                            /*isAlias=*/false)
             .fixItReplace(replaceRepr->getSourceRange(), fix);
       }