Alter members to be static and make observation methods be nonisolated for future actor adoption

Author: phausler

stdlib/public/Observation/Sources/Observation/MemberKeyPaths.swift

@@ -145,11 +145,11 @@ public struct MemberKeyPaths<Root>: SetAlgebra, Hashable {
 @available(SwiftStdlib 5.9, *)
 extension MemberKeyPaths where Root: Observable {
   @inlinable
-  public init(members: MemberKeyPaths<Root>, root: Root) {
+  public init(members: MemberKeyPaths<Root>) {
     self.init()
     for raw in members.raw {
       self.formUnion(
-        root.memberKeyPaths(for: 
+        Root.memberKeyPaths(for: 
           Unmanaged<PartialKeyPath<Root>>.fromOpaque(raw)
             .takeUnretainedValue()))
     }

stdlib/public/Observation/Sources/Observation/Observable.swift

@@ -14,18 +14,20 @@
 public protocol Observable: Identifiable {
   associatedtype Token
 
-  func addObserver(
+  nonisolated func addObserver(
     _ observer: some Observer<Self>, 
     for members: MemberKeyPaths<Self>, 
     using transactionModel: some ObservationTransactionModel
   ) -> Token
-  func removeObserver(_ observation: Token)
-  func memberKeyPaths(for keyPath: PartialKeyPath<Self>) -> MemberKeyPaths<Self>
+  nonisolated func removeObserver(_ observation: Token)
+  nonisolated static func memberKeyPaths(
+    for keyPath: PartialKeyPath<Self>
+  ) -> MemberKeyPaths<Self>
 }
 
 @available(SwiftStdlib 5.9, *)
 extension Observable {
-  public func addObserver<O: Observer>(
+  public nonisolated func addObserver<O: Observer>(
     _ observer: O, 
     for fields: MemberKeyPaths<Self>
   ) -> Token where O.Subject == Self {
@@ -34,15 +36,15 @@ extension Observable {
       using: ImmediateObservationTransactionModel())
   }
 
-  public func addObserver<Member>(
+  public nonisolated func addObserver<Member>(
     _ observer: some Observer<Self>, 
     for keyPath: KeyPath<Self, Member>, 
     using transactionModel: some ObservationTransactionModel
   ) -> Token {
     addObserver(observer, for: [keyPath], using: transactionModel)
   }
 
-  public func addObserver<O: Observer, Member>(
+  public nonisolated func addObserver<O: Observer, Member>(
     _ observer: O, 
     for keyPath: KeyPath<Self, Member>
   ) -> Token where O.Subject == Self {
@@ -51,7 +53,7 @@ extension Observable {
       using: ImmediateObservationTransactionModel())
   }
 
-  public func memberKeyPaths(
+  public nonisolated static func memberKeyPaths(
     for keyPath: PartialKeyPath<Self>
   ) -> MemberKeyPaths<Self> {
     return [keyPath]

stdlib/public/Observation/Sources/Observation/ObservationRegistrar.swift

@@ -94,10 +94,11 @@ public struct ObservationRegistar<Subject: Observable>: @unchecked Sendable {
 
   public func addObserver<Model: ObservationTransactionModel>(_ observer: some Observer<Subject>, for members: MemberKeyPaths<Subject>, using transactionModel: Model) -> ObservationToken {
     let token = ObservationToken()
+    let observedMembers = MemberKeyPaths(members: members)
     state.withCriticalRegion { state in
-      let entry = Entry(observer: observer, members: members, token: token, model: transactionModel)
+      let entry = Entry(observer: observer, members: observedMembers, token: token, model: transactionModel)
       state.observers[token] = entry
-      for keyPath in members.raw {
+      for keyPath in observedMembers.raw {
         state.registrations[keyPath, default: []].insert(entry)
       }
     }