Add workaround for double-call to macro extension method call

Author: natecook1000

test/stdlib/Observation/Observable.swift

@@ -17,29 +17,36 @@
 import StdlibUnittest
 import Observation
 
+@available(SwiftStdlib 5.9, *)
+@attached(member, names: named(_$observationRegistrar), named(access), named(withMutation), arbitrary)
+@attached(memberAttribute)
+@attached(extension, conformances: Observable)
+public macro ObservableTest() =
+  #externalMacro(module: "ObservationMacros", type: "ObservableMacro")
+
 @usableFromInline
 @inline(never)
 func _blackHole<T>(_ value: T) { }
 
-@Observable
-class ContainsNothing { }
+@ObservableTest
+public class ContainsNothing: Observable { }
 
-@Observable
+@ObservableTest
 class ContainsWeak {
   weak var obj: AnyObject? = nil
 }
 
-@Observable
-public class PublicContainsWeak {
-  public weak var obj: AnyObject? = nil
+@ObservableTest
+class PublicContainsWeak {
+  weak var obj: AnyObject? = nil
 }
 
-@Observable
+@ObservableTest
 class ContainsUnowned {
   unowned var obj: AnyObject? = nil
 }
 
-@Observable
+@ObservableTest
 class ContainsIUO {
   var obj: Int! = nil
 }
@@ -48,7 +55,7 @@ class NonObservable {
 
 }
 
-@Observable
+@ObservableTest
 class InheritsFromNonObservable: NonObservable {
 
 }
@@ -57,29 +64,29 @@ protocol NonObservableProtocol {
 
 }
 
-@Observable
+@ObservableTest
 class ConformsToNonObservableProtocol: NonObservableProtocol {
 
 }
 
 struct NonObservableContainer {
-  @Observable
+  @ObservableTest
   class ObservableContents {
     var field: Int = 3
   }
 }
 
-@Observable
+@ObservableTest
 final class SendableClass: Sendable {
   var field: Int = 3
 }
 
-@Observable
+@ObservableTest
 class CodableClass: Codable {
   var field: Int = 3
 }
 
-@Observable
+@ObservableTest
 final class HashableClass {
   var field: Int = 3
 }
@@ -94,7 +101,7 @@ extension HashableClass: Hashable {
   }
 }
 
-@Observable
+@ObservableTest
 class ImplementsAccessAndMutation {
   var field = 3
   let accessCalled: (PartialKeyPath<ImplementsAccessAndMutation>) -> Void
@@ -121,18 +128,18 @@ class ImplementsAccessAndMutation {
   }
 }
 
-@Observable
+@ObservableTest
 class HasIgnoredProperty {
   var field = 3
   @ObservationIgnored var ignored = 4
 }
 
-@Observable
+@ObservableTest
 class Entity {
   var age: Int = 0
 }
 
-@Observable
+@ObservableTest
 class Person : Entity {
   var firstName = ""
   var lastName = ""
@@ -142,30 +149,30 @@ class Person : Entity {
   var fullName: String { firstName + " " + lastName }
 }
 
-@Observable
+@ObservableTest
 class MiddleNamePerson: Person {
   var middleName = ""
 
   override var fullName: String { firstName + " " + middleName + " " + lastName }
 }
 
-@Observable
+@ObservableTest
 class IsolatedClass {
   @MainActor var test = "hello"
 }
 
 @MainActor
-@Observable
+@ObservableTest
 class IsolatedInstance {
   var test = "hello"
 }
 
-@Observable
+@ObservableTest
 class ClassHasExistingConformance: Observable { }
 
 protocol Intermediary: Observable { }
 
-@Observable
+@ObservableTest
 class HasIntermediaryConformance: Intermediary { }
 
 class CapturedState<State>: @unchecked Sendable {