Add enableUpcomingFeature("ExistentialAny") and update accordingly.

Enable the feature on all targets, and then go through doing the fixits within
Xcode 15 that are triggered as a result.

This basically replaces #1509

Package.swift

@@ -39,30 +39,41 @@ let package = Package(
         name: "SwiftProtobuf",
         exclude: ["CMakeLists.txt"],
         swiftSettings: [
+          .enableUpcomingFeature("ExistentialAny"),
           .enableExperimentalFeature("StrictConcurrency=complete"),
         ]
     ),
     .target(
         name: "SwiftProtobufPluginLibrary",
         dependencies: ["SwiftProtobuf"],
-        exclude: ["CMakeLists.txt"]
+        exclude: ["CMakeLists.txt"],
+        swiftSettings: [
+          .enableUpcomingFeature("ExistentialAny"),
+        ]
     ),
     .target(
         name: "SwiftProtobufTestHelpers",
         dependencies: ["SwiftProtobuf"],
         swiftSettings: [
+          .enableUpcomingFeature("ExistentialAny"),
           .enableExperimentalFeature("StrictConcurrency=complete"),
         ]
     ),
     .executableTarget(
         name: "protoc-gen-swift",
         dependencies: ["SwiftProtobufPluginLibrary", "SwiftProtobuf"],
-        exclude: ["CMakeLists.txt"]
+        exclude: ["CMakeLists.txt"],
+        swiftSettings: [
+          .enableUpcomingFeature("ExistentialAny")
+        ]
     ),
     .executableTarget(
         name: "Conformance",
         dependencies: ["SwiftProtobuf"],
-        exclude: ["failure_list_swift.txt", "text_format_failure_list_swift.txt"]
+        exclude: ["failure_list_swift.txt", "text_format_failure_list_swift.txt"],
+        swiftSettings: [
+          .enableUpcomingFeature("ExistentialAny"),
+        ]
     ),
     .plugin(
         name: "SwiftProtobufPlugin",
@@ -75,16 +86,25 @@ let package = Package(
         name: "SwiftProtobufTests",
         dependencies: ["SwiftProtobuf"],
         swiftSettings: [
+          .enableUpcomingFeature("ExistentialAny"),
           .enableExperimentalFeature("StrictConcurrency=complete"),
         ]
     ),
     .testTarget(
         name: "SwiftProtobufPluginLibraryTests",
-        dependencies: ["SwiftProtobufPluginLibrary", "SwiftProtobufTestHelpers"]
+        dependencies: ["SwiftProtobufPluginLibrary", "SwiftProtobufTestHelpers"],
+        swiftSettings: [
+          .enableUpcomingFeature("ExistentialAny"),
+          .enableExperimentalFeature("StrictConcurrency=complete"),
+        ]
     ),
     .testTarget(
         name: "protoc-gen-swiftTests",
-        dependencies: ["protoc-gen-swift", "SwiftProtobufTestHelpers"]
+        dependencies: ["protoc-gen-swift", "SwiftProtobufTestHelpers"],
+        swiftSettings: [
+          .enableUpcomingFeature("ExistentialAny"),
+          .enableExperimentalFeature("StrictConcurrency=complete"),
+        ]
     ),
   ],
   swiftLanguageVersions: [.v5]

Sources/Conformance/main.swift

@@ -84,8 +84,8 @@ func buildResponse(serializedBytes: [UInt8]) -> Conformance_ConformanceResponse
         return response
     }
 
-    let msgType: SwiftProtobuf.Message.Type
-    let extensions: SwiftProtobuf.ExtensionMap
+    let msgType: any SwiftProtobuf.Message.Type
+    let extensions: any SwiftProtobuf.ExtensionMap
     switch request.messageType {
     case "":
         // Note: This case is here to cover using a old version of the conformance test
@@ -102,7 +102,7 @@ func buildResponse(serializedBytes: [UInt8]) -> Conformance_ConformanceResponse
         return response
     }
 
-    let testMessage: SwiftProtobuf.Message
+    let testMessage: any SwiftProtobuf.Message
     switch request.payload {
     case .protobufPayload(let data)?:
         do {

Sources/SwiftProtobuf/AnyMessageStorage.swift

@@ -16,14 +16,14 @@
 import Foundation
 
 fileprivate func serializeAnyJSON(
-  for message: Message,
+  for message: any Message,
   typeURL: String,
   options: JSONEncodingOptions
 ) throws -> String {
   var visitor = try JSONEncodingVisitor(type: type(of: message), options: options)
   visitor.startObject(message: message)
   visitor.encodeField(name: "@type", stringValue: typeURL)
-  if let m = message as? _CustomJSONCodable {
+  if let m = message as? (any _CustomJSONCodable) {
     let value = try m.encodedJSONString(options: options)
     visitor.encodeField(name: "value", jsonText: value)
   } else {
@@ -33,7 +33,7 @@ fileprivate func serializeAnyJSON(
   return visitor.stringResult
 }
 
-fileprivate func emitVerboseTextForm(visitor: inout TextFormatEncodingVisitor, message: Message, typeURL: String) {
+fileprivate func emitVerboseTextForm(visitor: inout TextFormatEncodingVisitor, message: any Message, typeURL: String) {
   let url: String
   if typeURL.isEmpty {
     url = buildTypeURL(forMessage: message, typePrefix: defaultAnyTypeURLPrefix)
@@ -53,10 +53,10 @@ fileprivate func asJSONObject(body: [UInt8]) -> Data {
 }
 
 fileprivate func unpack(contentJSON: [UInt8],
-                        extensions: ExtensionMap,
+                        extensions: any ExtensionMap,
                         options: JSONDecodingOptions,
-                        as messageType: Message.Type) throws -> Message {
-  guard messageType is _CustomJSONCodable.Type else {
+                        as messageType: any Message.Type) throws -> any Message {
+  guard messageType is any _CustomJSONCodable.Type else {
     let contentJSONAsObject = asJSONObject(body: contentJSON)
     return try messageType.init(jsonUTF8Bytes: contentJSONAsObject, extensions: extensions, options: options)
   }
@@ -135,7 +135,7 @@ internal class AnyMessageStorage {
     // unpacking that takes new options when a developer decides to decode it.
     case binary(Data)
     // a message
-    case message(Message)
+    case message(any Message)
     // parsed JSON with the @type removed and the decoding options.
     case contentJSON([UInt8], JSONDecodingOptions)
   }
@@ -162,7 +162,7 @@ internal class AnyMessageStorage {
   // replaced during the unpacking and never as a merge.
   func unpackTo<M: Message>(
     target: inout M,
-    extensions: ExtensionMap?,
+    extensions: (any ExtensionMap)?,
     options: BinaryDecodingOptions
   ) throws {
     guard isA(M.self) else {

Sources/SwiftProtobuf/AsyncMessageSequence.swift

@@ -34,7 +34,7 @@ extension AsyncSequence where Element == UInt8 {
   @inlinable
   public func binaryProtobufDelimitedMessages<M: Message>(
     of messageType: M.Type = M.self,
-    extensions: ExtensionMap? = nil,
+    extensions: (any ExtensionMap)? = nil,
     partial: Bool = false,
     options: BinaryDecodingOptions = BinaryDecodingOptions()
   ) -> AsyncMessageSequence<Self, M> {
@@ -58,7 +58,7 @@ public struct AsyncMessageSequence<
   public typealias Element = M
 
   private let base: Base
-  private let extensions: ExtensionMap?
+  private let extensions: (any ExtensionMap)?
   private let partial: Bool
   private let options: BinaryDecodingOptions
 
@@ -80,7 +80,7 @@ public struct AsyncMessageSequence<
   ///           messages.
   public init(
     base: Base,
-    extensions: ExtensionMap? = nil,
+    extensions: (any ExtensionMap)? = nil,
     partial: Bool = false,
     options: BinaryDecodingOptions = BinaryDecodingOptions()
   ) {
@@ -95,15 +95,15 @@ public struct AsyncMessageSequence<
     @usableFromInline
     var iterator: Base.AsyncIterator?
     @usableFromInline
-    let extensions: ExtensionMap?
+    let extensions: (any ExtensionMap)?
     @usableFromInline
     let partial: Bool
     @usableFromInline
     let options: BinaryDecodingOptions
 
     init(
       iterator: Base.AsyncIterator,
-      extensions: ExtensionMap?,
+      extensions: (any ExtensionMap)?,
       partial: Bool,
       options: BinaryDecodingOptions
     ) {

Sources/SwiftProtobuf/BinaryDecoder.swift

@@ -33,7 +33,7 @@ internal struct BinaryDecoder: Decoder {
     // Field number for last-parsed field tag
     private var fieldNumber: Int = 0
     // Collection of extension fields for this decode
-    private var extensions: ExtensionMap?
+    private var extensions: (any ExtensionMap)?
     // The current group number. See decodeFullGroup(group:fieldNumber:) for how
     // this is used.
     private var groupFieldNumber: Int?
@@ -54,7 +54,7 @@ internal struct BinaryDecoder: Decoder {
       forReadingFrom pointer: UnsafeRawPointer,
       count: Int,
       options: BinaryDecodingOptions,
-      extensions: ExtensionMap? = nil
+      extensions: (any ExtensionMap)? = nil
     ) {
         // Assuming baseAddress is not nil.
         p = pointer
@@ -1088,7 +1088,7 @@ internal struct BinaryDecoder: Decoder {
 
     internal mutating func decodeExtensionField(
       values: inout ExtensionFieldValueSet,
-      messageType: Message.Type,
+      messageType: any Message.Type,
       fieldNumber: Int
     ) throws {
         if let ext = extensions?[messageType, fieldNumber] {
@@ -1102,9 +1102,9 @@ internal struct BinaryDecoder: Decoder {
     /// Helper to reuse between Extension decoding and MessageSet Extension decoding.
     private mutating func decodeExtensionField(
       values: inout ExtensionFieldValueSet,
-      messageType: Message.Type,
+      messageType: any Message.Type,
       fieldNumber: Int,
-      messageExtension ext: AnyMessageExtension
+      messageExtension ext: any AnyMessageExtension
     ) throws {
         assert(!consumed)
         assert(fieldNumber == ext.fieldNumber)
@@ -1129,7 +1129,7 @@ internal struct BinaryDecoder: Decoder {
 
     internal mutating func decodeExtensionFieldsAsMessageSet(
       values: inout ExtensionFieldValueSet,
-      messageType: Message.Type
+      messageType: any Message.Type
     ) throws {
         // Spin looking for the Item group, everything else will end up in unknown fields.
         while let fieldNumber = try self.nextFieldNumber() {
@@ -1173,14 +1173,14 @@ internal struct BinaryDecoder: Decoder {
 
     private mutating func decodeMessageSetItem(
       values: inout ExtensionFieldValueSet,
-      messageType: Message.Type
+      messageType: any Message.Type
     ) throws -> DecodeMessageSetItemResult {
         // This is loosely based on the C++:
         //   ExtensionSet::ParseMessageSetItem()
         //   WireFormat::ParseAndMergeMessageSetItem()
         // (yes, there have two versions that are almost the same)
 
-        var msgExtension: AnyMessageExtension?
+      var msgExtension: (any AnyMessageExtension)?
         var fieldData: Data?
 
         // In this loop, if wire types are wrong, things don't decode,

Sources/SwiftProtobuf/BinaryDelimited.swift

@@ -65,7 +65,7 @@ public enum BinaryDelimited {
   ///           `BinaryDelimited.Error` for some writing errors, or the
   ///           underlying `OutputStream.streamError` for a stream error.
   public static func serialize(
-    message: Message,
+    message: any Message,
     to stream: OutputStream,
     partial: Bool = false
   ) throws {
@@ -125,7 +125,7 @@ public enum BinaryDelimited {
   public static func parse<M: Message>(
     messageType: M.Type,
     from stream: InputStream,
-    extensions: ExtensionMap? = nil,
+    extensions: (any ExtensionMap)? = nil,
     partial: Bool = false,
     options: BinaryDecodingOptions = BinaryDecodingOptions()
   ) throws -> M {
@@ -166,7 +166,7 @@ public enum BinaryDelimited {
   public static func merge<M: Message>(
     into message: inout M,
     from stream: InputStream,
-    extensions: ExtensionMap? = nil,
+    extensions: (any ExtensionMap)? = nil,
     partial: Bool = false,
     options: BinaryDecodingOptions = BinaryDecodingOptions()
   ) throws {

Sources/SwiftProtobuf/Decoder.swift

@@ -204,11 +204,11 @@ public protocol Decoder {
   // Decode extension fields
 
   /// Decode an extension field
-  mutating func decodeExtensionField(values: inout ExtensionFieldValueSet, messageType: Message.Type, fieldNumber: Int) throws
+  mutating func decodeExtensionField(values: inout ExtensionFieldValueSet, messageType: any Message.Type, fieldNumber: Int) throws
 
   // Run a decode loop decoding the MessageSet format for Extensions.
   mutating func decodeExtensionFieldsAsMessageSet(values: inout ExtensionFieldValueSet,
-                                                  messageType: Message.Type) throws
+                                                  messageType: any Message.Type) throws
 }
 
 /// Most Decoders won't care about Extension handing as in MessageSet
@@ -217,7 +217,7 @@ public protocol Decoder {
 extension Decoder {
   public mutating func decodeExtensionFieldsAsMessageSet(
     values: inout ExtensionFieldValueSet,
-    messageType: Message.Type
+    messageType: any Message.Type
   ) throws {
     while let fieldNumber = try self.nextFieldNumber() {
       try self.decodeExtensionField(values: &values,

Sources/SwiftProtobuf/Enum.swift

@@ -49,7 +49,7 @@ extension Enum {
   /// Since the text format and JSON names are always identical, we don't need
   /// to distinguish them.
   internal var name: _NameMap.Name? {
-    guard let nameProviding = Self.self as? _ProtoNameProviding.Type else {
+    guard let nameProviding = Self.self as? any _ProtoNameProviding.Type else {
       return nil
     }
     return nameProviding._protobuf_nameMap.names(for: rawValue)?.proto
@@ -63,7 +63,7 @@ extension Enum {
   ///
   /// - Parameter name: The name of the enum case.
   internal init?(name: String) {
-    guard let nameProviding = Self.self as? _ProtoNameProviding.Type,
+    guard let nameProviding = Self.self as? any _ProtoNameProviding.Type,
       let number = nameProviding._protobuf_nameMap.number(forJSONName: name) else {
       return nil
     }
@@ -78,7 +78,7 @@ extension Enum {
   ///
   /// - Parameter name: Buffer holding the UTF-8 bytes of the desired name.
   internal init?(rawUTF8: UnsafeRawBufferPointer) {
-    guard let nameProviding = Self.self as? _ProtoNameProviding.Type,
+    guard let nameProviding = Self.self as? any _ProtoNameProviding.Type,
       let number = nameProviding._protobuf_nameMap.number(forJSONName: rawUTF8) else {
       return nil
     }

Sources/SwiftProtobuf/ExtensionFieldValueSet.swift

@@ -15,7 +15,7 @@
 // -----------------------------------------------------------------------------
 
 public struct ExtensionFieldValueSet: Hashable, Sendable {
-  fileprivate var values = [Int : AnyExtensionField]()
+  fileprivate var values = [Int : any AnyExtensionField]()
 
   public static func ==(lhs: ExtensionFieldValueSet,
                         rhs: ExtensionFieldValueSet) -> Bool {
@@ -62,12 +62,12 @@ public struct ExtensionFieldValueSet: Hashable, Sendable {
     }
   }
 
-  public subscript(index: Int) -> AnyExtensionField? {
+  public subscript(index: Int) -> (any AnyExtensionField)? {
     get { return values[index] }
     set { values[index] = newValue }
   }
 
-  mutating func modify<ReturnType>(index: Int, _ modifier: (inout AnyExtensionField?) throws -> ReturnType) rethrows -> ReturnType {
+  mutating func modify<ReturnType>(index: Int, _ modifier: (inout (any AnyExtensionField)?) throws -> ReturnType) rethrows -> ReturnType {
     // This internal helper exists to invoke the _modify accessor on Dictionary for the given operation, which can avoid CoWs
     // during the modification operation.
     return try modifier(&values[index])