Revert SE-0283 (swiftlang#34492)

Reverted despite build failures.

Author: Azoy

include/swift/ABI/Metadata.h

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -2295,28 +2295,37 @@ struct TargetTypeMetadataRecord {
   union {
     /// A direct reference to a nominal type descriptor.
     RelativeDirectPointerIntPair<TargetContextDescriptor<Runtime>,
-                                 TypeMetadataRecordKind>
+                                 TypeReferenceKind>
       DirectNominalTypeDescriptor;
 
     /// An indirect reference to a nominal type descriptor.
     RelativeDirectPointerIntPair<TargetSignedPointer<Runtime, TargetContextDescriptor<Runtime> * __ptrauth_swift_type_descriptor>,
-                                 TypeMetadataRecordKind>
+                                 TypeReferenceKind>
       IndirectNominalTypeDescriptor;
+
+    // We only allow a subset of the TypeReferenceKinds here.
+    // Should we just acknowledge that this is a different enum?
   };
 
 public:
-  TypeMetadataRecordKind getTypeKind() const {
+  TypeReferenceKind getTypeKind() const {
     return DirectNominalTypeDescriptor.getInt();
   }
 
   const TargetContextDescriptor<Runtime> *
   getContextDescriptor() const {
     switch (getTypeKind()) {
-    case TypeMetadataRecordKind::DirectTypeDescriptor:
+    case TypeReferenceKind::DirectTypeDescriptor:
       return DirectNominalTypeDescriptor.getPointer();
 
-    case TypeMetadataRecordKind::IndirectTypeDescriptor:
+    case TypeReferenceKind::IndirectTypeDescriptor:
       return *IndirectNominalTypeDescriptor.getPointer();
+
+    // These types (and any others we might add to TypeReferenceKind
+    // in the future) are just never used in these lists.
+    case TypeReferenceKind::DirectObjCClassName:
+    case TypeReferenceKind::IndirectObjCClass:
+      return nullptr;
     }
 
     return nullptr;
@@ -2406,9 +2415,6 @@ struct TargetTypeReference {
     /// A direct reference to an Objective-C class name.
     RelativeDirectPointer<const char>
       DirectObjCClassName;
-
-    /// A "reference" to some metadata kind, e.g. tuple.
-    MetadataKind MetadataKind;
   };
 
   const TargetContextDescriptor<Runtime> *
@@ -2422,18 +2428,12 @@ struct TargetTypeReference {
 
     case TypeReferenceKind::DirectObjCClassName:
     case TypeReferenceKind::IndirectObjCClass:
-    case TypeReferenceKind::MetadataKind:
       return nullptr;
     }
 
     return nullptr;
   }
 
-  enum MetadataKind getMetadataKind(TypeReferenceKind kind) const {
-    assert(kind == TypeReferenceKind::MetadataKind);
-    return MetadataKind;
-  }
-
 #if SWIFT_OBJC_INTEROP
   /// If this type reference is one of the kinds that supports ObjC
   /// references,
@@ -2519,10 +2519,6 @@ struct TargetProtocolConformanceDescriptor final
     return Flags.getTypeReferenceKind();
   }
 
-  enum MetadataKind getMetadataKind() const {
-    return TypeRef.getMetadataKind(getTypeKind());
-  }
-
   const char *getDirectObjCClassName() const {
     return TypeRef.getDirectObjCClassName(getTypeKind());
   }
@@ -2550,11 +2546,6 @@ struct TargetProtocolConformanceDescriptor final
         TargetRelativeContextPointer<Runtime>>();
   }
 
-  /// Whether this conformance is builtin by the compiler + runtime.
-  bool isBuiltin() const {
-    return getTypeKind() == TypeReferenceKind::MetadataKind;
-  }
-
   /// Whether this conformance is non-unique because it has been synthesized
   /// for a foreign type.
   bool isSynthesizedNonUnique() const {

include/swift/ABI/MetadataValues.h

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -361,19 +361,7 @@ enum : unsigned {
   NumGenericMetadataPrivateDataWords = 16,
 };
 
-/// Kinds of type metadata reocrds.
-enum class TypeMetadataRecordKind : unsigned {
-  /// A direct reference to a nominal type descriptor.
-  DirectTypeDescriptor = 0x00,
-
-  /// An indirect reference to a nominal type descriptor.
-  IndirectTypeDescriptor = 0x01,
-
-  First_Kind = DirectTypeDescriptor,
-  Last_Kind = IndirectTypeDescriptor,
-};
-
-/// Kinds of references to type metadata.
+/// Kinds of type metadata/protocol conformance records.
 enum class TypeReferenceKind : unsigned {
   /// The conformance is for a nominal type referenced directly;
   /// getTypeDescriptor() points to the type context descriptor.
@@ -396,14 +384,10 @@ enum class TypeReferenceKind : unsigned {
   /// unused.
   IndirectObjCClass = 0x03,
 
-  /// The conformance is for a non-nominal type whose metadata kind we recorded;
-  /// getMetadataKind() returns the kind.
-  MetadataKind = 0x04,
-
   // We only reserve three bits for this in the various places we store it.
 
   First_Kind = DirectTypeDescriptor,
-  Last_Kind = MetadataKind,
+  Last_Kind = IndirectObjCClass,
 };
 
 /// Flag that indicates whether an existential type is class-constrained or not.

include/swift/AST/ASTContext.h

@@ -103,7 +103,6 @@ namespace swift {
   class InheritedProtocolConformance;
   class SelfProtocolConformance;
   class SpecializedProtocolConformance;
-  class BuiltinProtocolConformance;
   enum class ProtocolConformanceState;
   class Pattern;
   enum PointerTypeKind : unsigned;
@@ -949,11 +948,6 @@ class ASTContext final {
   SelfProtocolConformance *
   getSelfConformance(ProtocolDecl *protocol);
 
-  /// Produce the builtin conformance for some structural type to some protocol.
-  BuiltinProtocolConformance *
-  getBuiltinConformance(Type type, ProtocolDecl *protocol,
-                        ArrayRef<ProtocolConformanceRef> conformances);
-
   /// A callback used to produce a diagnostic for an ill-formed protocol
   /// conformance that was type-checked before we're actually walking the
   /// conformance itself, along with a bit indicating whether this diagnostic

include/swift/AST/ProtocolConformance.h

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -66,10 +66,7 @@ enum class ProtocolConformanceKind {
   Specialized,
   /// Conformance of a generic class type projected through one of its
   /// superclass's conformances.
-  Inherited,
-  /// Builtin conformances are special conformaces that the runtime handles
-  /// and isn't implemented directly in Swift.
-  Builtin
+  Inherited
 };
 
 /// Describes the state of a protocol conformance, which may be complete,
@@ -332,9 +329,7 @@ class alignas(1 << DeclAlignInBits) ProtocolConformance {
 /// - the type is directly declared to conform to the protocol (a
 ///   normal conformance) or
 /// - the protocol's existential type is known to conform to itself (a
-///   self-conformance) or
-/// - the type's conformance is declared within the runtime (a builtin
-///   conformance).
+///   self-conformance).
 class RootProtocolConformance : public ProtocolConformance {
 protected:
   RootProtocolConformance(ProtocolConformanceKind kind, Type conformingType)
@@ -385,8 +380,7 @@ class RootProtocolConformance : public ProtocolConformance {
 
   static bool classof(const ProtocolConformance *conformance) {
     return conformance->getKind() == ProtocolConformanceKind::Normal ||
-           conformance->getKind() == ProtocolConformanceKind::Self ||
-           conformance->getKind() == ProtocolConformanceKind::Builtin;
+           conformance->getKind() == ProtocolConformanceKind::Self;
   }
 };
 
@@ -1020,110 +1014,6 @@ class InheritedProtocolConformance : public ProtocolConformance,
   }
 };
 
-/// A builtin conformance appears when a special non-nominal type has a runtime
-/// declared conformance. E.g. the runtime implements Equatable for tuples.
-class BuiltinProtocolConformance final : public RootProtocolConformance,
-      private llvm::TrailingObjects<BuiltinProtocolConformance,
-                                    ProtocolConformanceRef> {
-  friend ASTContext;
-  friend TrailingObjects;
-
-  ProtocolDecl *protocol = nullptr;
-  size_t numConformances;
-
-  mutable Optional<ArrayRef<Requirement>> conditionalConformances = None;
-
-  BuiltinProtocolConformance(Type conformingType, ProtocolDecl *protocol,
-                             ArrayRef<ProtocolConformanceRef> conformances);
-
-  size_t numTrailingObjects(OverloadToken<ProtocolConformanceRef>) const {
-    return numConformances;
-  }
-
-public:
-  /// Get the protocol being conformed to.
-  ProtocolDecl *getProtocol() const {
-    return protocol;
-  }
-
-  /// Get the trailing conformances that this builtin conformance needs.
-  MutableArrayRef<ProtocolConformanceRef> getConformances() {
-    return {getTrailingObjects<ProtocolConformanceRef>(), numConformances};
-  }
-
-  /// Get the trailing conformances that this builtin conformance needs.
-  ArrayRef<ProtocolConformanceRef> getConformances() const {
-    return {getTrailingObjects<ProtocolConformanceRef>(), numConformances};
-  }
-
-  /// Get any requirements that must be satisfied for this conformance to apply.
-  Optional<ArrayRef<Requirement>>
-  getConditionalRequirementsIfAvailable() const {
-    return ArrayRef<Requirement>();
-  }
-
-  /// Get any requirements that must be satisfied for this conformance to apply.
-  ArrayRef<Requirement> getConditionalRequirements() const;
-
-  /// Get the declaration context that contains the nominal type declaration.
-  DeclContext *getDeclContext() const {
-    return getProtocol();
-  }
-
-  /// Retrieve the state of this conformance.
-  ProtocolConformanceState getState() const {
-    return ProtocolConformanceState::Complete;
-  }
-
-  /// Get the kind of source from which this conformance comes.
-  ConformanceEntryKind getSourceKind() const {
-    return ConformanceEntryKind::Synthesized;
-  }
-  /// Get the protocol conformance which implied this implied conformance.
-  NormalProtocolConformance *getImplyingConformance() const {
-    return nullptr;
-  }
-
-  bool hasTypeWitness(AssociatedTypeDecl *assocType) const {
-    llvm_unreachable("builtin-conformances currently don't have associated \
-                     types");
-  }
-
-  /// Retrieve the type witness and type decl (if one exists)
-  /// for the given associated type.
-  TypeWitnessAndDecl
-  getTypeWitnessAndDecl(AssociatedTypeDecl *assocType,
-                        SubstOptions options=None) const {
-    llvm_unreachable("builtin-conformances currently don't have associated \
-                     types");
-  }
-
-  /// Given that the requirement signature of the protocol directly states
-  /// that the given dependent type must conform to the given protocol,
-  /// return its associated conformance.
-  ProtocolConformanceRef
-  getAssociatedConformance(Type assocType, ProtocolDecl *protocol) const {
-    llvm_unreachable("builtin-conformances currently don't have associated \
-                     types");
-  }
-
-  /// Retrieve the witness corresponding to the given value requirement.
-  ConcreteDeclRef getWitnessDeclRef(ValueDecl *requirement) const {
-    return ConcreteDeclRef(requirement);
-  }
-
-  /// Determine whether the witness for the given requirement
-  /// is either the default definition or was otherwise deduced.
-  bool usesDefaultDefinition(AssociatedTypeDecl *requirement) const {
-    llvm_unreachable("builtin-conformances currently don't have associated \
-                     types");
-  }
-
-  static bool classof(const ProtocolConformance *conformance) {
-    return conformance->getKind() == ProtocolConformanceKind::Builtin;
-  }
-};
-
 inline bool ProtocolConformance::isInvalid() const {
   return getRootConformance()->isInvalid();
 }

include/swift/Frontend/BackDeploymentLibs.def

@@ -26,7 +26,6 @@
 
 BACK_DEPLOYMENT_LIB((5, 0), all, "swiftCompatibility50")
 BACK_DEPLOYMENT_LIB((5, 1), all, "swiftCompatibility51")
-BACK_DEPLOYMENT_LIB((5, 3), all, "swiftCompatibility53")
 BACK_DEPLOYMENT_LIB((5, 0), executable, "swiftCompatibilityDynamicReplacements")
 
 #undef BACK_DEPLOYMENT_LIB

include/swift/Remote/MetadataReader.h

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -1414,9 +1414,6 @@ class MetadataReader {
 
       return metadataFn(metadata);
     }
-    case TypeReferenceKind::MetadataKind: {
-      return None;
-    }
     }
 
     return None;