(134376602) Change @_nonSendable to unavailable extensions (#892)

Author: jmschonfeld

Sources/FoundationEssentials/AttributedString/AttributeScope.swift

@@ -22,11 +22,17 @@ public protocol AttributeScope : DecodingConfigurationProviding, EncodingConfigu
     static var encodingConfiguration: AttributeScopeCodableConfiguration { get }
 }
 
-@_nonSendable
 @frozen
 @available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
 public enum AttributeScopes { }
 
+@available(macOS, unavailable, introduced: 12.0)
+@available(iOS, unavailable, introduced: 15.0)
+@available(tvOS, unavailable, introduced: 15.0)
+@available(watchOS, unavailable, introduced: 8.0)
+@available(*, unavailable)
+extension AttributeScopes : Sendable {}
+
 #if FOUNDATION_FRAMEWORK
 
 import Darwin

Sources/FoundationEssentials/AttributedString/AttributedStringAttribute.swift

@@ -133,7 +133,6 @@ extension AttributedStringKey {
 
 // MARK: Attribute Scopes
 
-@_nonSendable
 @dynamicMemberLookup @frozen
 @available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
 public enum AttributeDynamicLookup {
@@ -142,6 +141,13 @@ public enum AttributeDynamicLookup {
     }
 }
 
+@available(macOS, unavailable, introduced: 12.0)
+@available(iOS, unavailable, introduced: 15.0)
+@available(tvOS, unavailable, introduced: 15.0)
+@available(watchOS, unavailable, introduced: 8.0)
+@available(*, unavailable)
+extension AttributeDynamicLookup : Sendable {}
+
 @dynamicMemberLookup
 @available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
 public struct ScopedAttributeContainer<S: AttributeScope> : Sendable {