Revert "SR-0140: Bridge Optionals to nonnull ObjC objects by bridging their payload, or using a sentinel."

lib/AST/ASTContext.cpp

@@ -3879,22 +3879,18 @@ ASTContext::getForeignRepresentationInfo(NominalTypeDecl *nominal,
        known->second.getGeneration() < CurrentGeneration)) {
     Optional<ForeignRepresentationInfo> result;
 
-    // Look for a conformance to _ObjectiveCBridgeable (other than Optional's--
-    // we don't want to allow exposing APIs with double-optional types like
-    // NSObject??, even though Optional is bridged to its underlying type).
+    // Look for a conformance to _ObjectiveCBridgeable.
     //
     // FIXME: We're implicitly depending on the fact that lookupConformance
     // is global, ignoring the module we provide for it.
-    if (nominal != dc->getASTContext().getOptionalDecl()) {
-      if (auto objcBridgeable
-            = getProtocol(KnownProtocolKind::ObjectiveCBridgeable)) {
-        if (auto conformance
-              = dc->getParentModule()->lookupConformance(
-                  nominal->getDeclaredType(), objcBridgeable,
-                  getLazyResolver())) {
-          result =
-              ForeignRepresentationInfo::forBridged(conformance->getConcrete());
-        }
+    if (auto objcBridgeable
+          = getProtocol(KnownProtocolKind::ObjectiveCBridgeable)) {
+      if (auto conformance
+            = dc->getParentModule()->lookupConformance(
+                nominal->getDeclaredType(), objcBridgeable,
+                getLazyResolver())) {
+        result =
+            ForeignRepresentationInfo::forBridged(conformance->getConcrete());
       }
     }
 
@@ -3990,11 +3986,6 @@ Type ASTContext::getBridgedToObjC(const DeclContext *dc, Type type,
   // Try to find a conformance that will enable bridging.
   auto findConformance =
     [&](KnownProtocolKind known) -> Optional<ProtocolConformanceRef> {
-      // Don't ascribe any behavior to Optional other than what we explicitly
-      // give it. We don't want things like AnyObject?? to work.
-      if (type->getAnyNominal() == getOptionalDecl())
-        return None;
-
       // Find the protocol.
       auto proto = getProtocol(known);
       if (!proto) return None;

lib/AST/Builtins.cpp

@@ -702,7 +702,6 @@ static ValueDecl *getIsOptionalOperation(ASTContext &Context, Identifier Id) {
   return builder.build(Id);
 }
 
-
 static ValueDecl *getAllocOperation(ASTContext &Context, Identifier Id) {
   Type PtrSizeTy = BuiltinIntegerType::getWordType(Context);
   Type ResultTy = Context.TheRawPointerType;

lib/SILGen/SILGenBridging.cpp

@@ -70,15 +70,6 @@ emitBridgeNativeToObjectiveC(SILGenFunction &gen,
     witnessFnTy = witnessFnTy.substGenericArgs(gen.SGM.M, substitutions);
   }
 
-  // The witness may be more abstract than the concrete value we're bridging,
-  // for instance, if the value is a concrete instantiation of a generic type.
-  if (witnessFnTy.castTo<SILFunctionType>()->getParameters()[0].isIndirect()
-      && !swiftValue.getType().isAddress()) {
-    auto tmp = gen.emitTemporaryAllocation(loc, swiftValue.getType());
-    gen.B.createStore(loc, swiftValue.getValue(), tmp);
-    swiftValue = ManagedValue::forUnmanaged(tmp);
-  }
-
   // Call the witness.
   SILType resultTy = gen.getLoweredType(objcType);
   SILValue bridgedValue = gen.B.createApply(loc, witnessRef, witnessFnTy,

lib/SILOptimizer/Utils/Local.cpp

@@ -1662,11 +1662,6 @@ optimizeBridgedSwiftToObjCCast(SILInstruction *Inst,
 
   auto SILFnTy = SILType::getPrimitiveObjectType(
       M.Types.getConstantFunctionType(BridgeFuncDeclRef));
-
-  // TODO: Handle indirect argument to or return from witness function.
-  if (ParamTypes[0].isIndirect()
-      || BridgedFunc->getLoweredFunctionType()->getSingleResult().isIndirect())
-    return nullptr;
 
   // Get substitutions, if source is a bound generic type.
   ArrayRef<Substitution> Subs =
@@ -1733,9 +1728,9 @@ optimizeBridgedSwiftToObjCCast(SILInstruction *Inst,
     case ParameterConvention::Direct_Unowned:
       break;
     case ParameterConvention::Indirect_In:
-    case ParameterConvention::Indirect_In_Guaranteed:
     case ParameterConvention::Indirect_Inout:
     case ParameterConvention::Indirect_InoutAliasable:
+    case ParameterConvention::Indirect_In_Guaranteed:
     case ParameterConvention::Direct_Deallocating:
       llvm_unreachable("unsupported convention for bridging conversion");
   }

stdlib/public/core/Optional.swift

@@ -487,78 +487,3 @@ extension Optional {
   }
 
 }
-
-//===----------------------------------------------------------------------===//
-// Bridging
-//===----------------------------------------------------------------------===//
-
-#if _runtime(_ObjC)
-extension Optional : _ObjectiveCBridgeable {
-  // The object that represents `none` for an Optional of this type.
-  internal static var _nilSentinel : AnyObject {
-    @_silgen_name("_swift_Foundation_getOptionalNilSentinelObject")
-    get
-  }
-
-  public func _bridgeToObjectiveC() -> AnyObject {
-    // Bridge a wrapped value by unwrapping.
-    if let value = self {
-      return _bridgeAnythingToObjectiveC(value)
-    }
-    // Bridge nil using a sentinel.
-    return type(of: self)._nilSentinel
-  }
-
-  public static func _forceBridgeFromObjectiveC(_ source: AnyObject,
-                                         result: inout Optional<Wrapped>?) {
-    // Map the nil sentinel back to .none.
-    // NB that the signature of _forceBridgeFromObjectiveC adds another level
-    // of optionality, so we need to wrap the immediate result of the conversion
-    // in `.some`.
-    if source === _nilSentinel {
-      result = .some(.none)
-      return
-    }
-    // Otherwise, force-bridge the underlying value.
-    let unwrappedResult = source as! Wrapped
-    result = .some(.some(unwrappedResult))
-  }
-
-  public static func _conditionallyBridgeFromObjectiveC(_ source: AnyObject,
-                                             result: inout Optional<Wrapped>?)
-      -> Bool {
-    // Map the nil sentinel back to .none.
-    // NB that the signature of _forceBridgeFromObjectiveC adds another level
-    // of optionality, so we need to wrap the immediate result of the conversion
-    // in `.some` to indicate success of the bridging operation, with a nil
-    // result.
-    if source === _nilSentinel {
-      result = .some(.none)
-      return true
-    }
-    // Otherwise, try to bridge the underlying value.
-    if let unwrappedResult = source as? Wrapped {
-      result = .some(.some(unwrappedResult))
-      return true
-    } else {
-      result = .none
-      return false
-    }
-  }
-
-  public static func _unconditionallyBridgeFromObjectiveC(_ source: AnyObject?)
-      -> Optional<Wrapped> {
-    if let nonnullSource = source {
-      // Map the nil sentinel back to none.
-      if nonnullSource === _nilSentinel {
-        return .none
-      } else {
-        return .some(nonnullSource as! Wrapped)
-      }
-    } else {
-      // If we unexpectedly got nil, just map it to `none` too.
-      return .none
-    }
-  }
-}
-#endif

stdlib/public/runtime/Casting.cpp

@@ -2513,18 +2513,6 @@ bool swift::swift_dynamicCast(OpaqueValue *dest,
     // unwrapping the target. This handles an optional source wrapped within an
     // existential that Optional conforms to (Any).
     if (auto srcExistentialType = dyn_cast<ExistentialTypeMetadata>(srcType)) {
-#if SWIFT_OBJC_INTEROP
-      // If coming from AnyObject, we may want to bridge.
-      if (srcExistentialType->Flags.getSpecialProtocol()
-            == SpecialProtocol::AnyObject) {
-        if (auto targetBridgeWitness = findBridgeWitness(targetType)) {
-          return _dynamicCastClassToValueViaObjCBridgeable(dest, src, srcType,
-                                                           targetType,
-                                                           targetBridgeWitness,
-                                                           flags);
-        }
-      }
-#endif
       return _dynamicCastFromExistential(dest, src, srcExistentialType,
                                          targetType, flags);
     }

stdlib/public/stubs/CMakeLists.txt

@@ -6,7 +6,6 @@ if(SWIFT_HOST_VARIANT MATCHES "${SWIFT_DARWIN_VARIANTS}")
       Availability.mm
       DispatchShims.mm
       FoundationHelpers.mm
-      OptionalBridgingHelper.mm
       Reflection.mm
       SwiftNativeNSXXXBase.mm.gyb)
   set(LLVM_OPTIONAL_SOURCES

test/SILGen/objc_bridging_any.swift

@@ -126,29 +126,27 @@ func passingToId<T: CP, U>(receiver: NSIdLover,
   // CHECK: apply [[METHOD]]([[ANYOBJECT]], [[SELF]])
   receiver.takesId(knownUnbridged)
 
-  // These cases bridge using Optional's _ObjectiveCBridgeable conformance.
-
   // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF]] : $NSIdLover,
-  // CHECK: [[BRIDGE_OPTIONAL:%.*]] = function_ref @_TFSq19_bridgeToObjectiveCfT_Ps9AnyObject_
   // CHECK: [[TMP:%.*]] = alloc_stack $Optional<String>
   // CHECK: store [[OPT_STRING]] to [[TMP]]
-  // CHECK: [[ANYOBJECT:%.*]] = apply [[BRIDGE_OPTIONAL]]<String>([[TMP]])
+  // CHECK: [[BRIDGE_ANYTHING:%.*]] = function_ref @_TFs27_bridgeAnythingToObjectiveC
+  // CHECK: [[ANYOBJECT:%.*]] = apply [[BRIDGE_ANYTHING]]<Optional<String>>([[TMP]])
   // CHECK: apply [[METHOD]]([[ANYOBJECT]], [[SELF]])
   receiver.takesId(optionalA)
 
   // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF]] : $NSIdLover,
-  // CHECK: [[BRIDGE_OPTIONAL:%.*]] = function_ref @_TFSq19_bridgeToObjectiveCfT_Ps9AnyObject_
   // CHECK: [[TMP:%.*]] = alloc_stack $Optional<NSString>
   // CHECK: store [[OPT_NSSTRING]] to [[TMP]]
-  // CHECK: [[ANYOBJECT:%.*]] = apply [[BRIDGE_OPTIONAL]]<NSString>([[TMP]])
+  // CHECK: [[BRIDGE_ANYTHING:%.*]] = function_ref @_TFs27_bridgeAnythingToObjectiveC
+  // CHECK: [[ANYOBJECT:%.*]] = apply [[BRIDGE_ANYTHING]]<Optional<NSString>>([[TMP]])
   // CHECK: apply [[METHOD]]([[ANYOBJECT]], [[SELF]])
   receiver.takesId(optionalB)
 
   // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF]] : $NSIdLover,
   // CHECK: [[TMP:%.*]] = alloc_stack $Optional<Any>
   // CHECK: copy_addr [[OPT_ANY]] to [initialization] [[TMP]]
-  // CHECK: [[BRIDGE_OPTIONAL:%.*]] = function_ref @_TFSq19_bridgeToObjectiveCfT_Ps9AnyObject_
-  // CHECK: [[ANYOBJECT:%.*]] = apply [[BRIDGE_OPTIONAL]]<Any>([[TMP]])
+  // CHECK: [[BRIDGE_ANYTHING:%.*]] = function_ref @_TFs27_bridgeAnythingToObjectiveC
+  // CHECK: [[ANYOBJECT:%.*]] = apply [[BRIDGE_ANYTHING]]<Optional<Any>>([[TMP]])
   // CHECK: apply [[METHOD]]([[ANYOBJECT]], [[SELF]])
   receiver.takesId(optionalC)