[Diagnostics] Clarify the wording of error_in_future_swift_version.

Author: hborla

include/swift/AST/DiagnosticsCommon.def

@@ -45,7 +45,7 @@ NOTE(brace_stmt_suggest_do,none,
      "did you mean to use a 'do' statement?", ())
 
 WARNING(error_in_future_swift_version,none,
-        "%0; this is an error in Swift %1",
+        "%0; this is an error in the Swift %1 language mode",
         (DiagnosticInfo *, unsigned))
 
 // Generic disambiguation

include/swift/AST/DiagnosticsSema.def

@@ -6802,7 +6802,7 @@ WARNING(inlinable_decl_ref_from_hidden_module_warn,
       none, "%kind0 cannot be used in " FRAGILE_FUNC_KIND "1 "
       "because %select{<<ERROR>>|<<ERROR>>|<<ERROR>>|<<ERROR>>|"
       "%2 was not imported by this file}3"
-      "; this is an error in Swift 6",
+      "; this is an error in the Swift 6 language mode",
       (const ValueDecl *, unsigned, Identifier, unsigned))
 
 ERROR(inlinable_typealias_desugars_to_type_from_hidden_module,

test/ClangImporter/objc_async.swift

@@ -298,7 +298,7 @@ class BarFrame: PictureFrame {
 @available(SwiftStdlib 5.5, *)
 @SomeGlobalActor
 class BazFrame: NotIsolatedPictureFrame {
-// expected-warning@-1 {{global actor 'SomeGlobalActor'-isolated class 'BazFrame' has different actor isolation from nonisolated superclass 'NotIsolatedPictureFrame'; this is an error in Swift 6}}
+// expected-warning@-1 {{global actor 'SomeGlobalActor'-isolated class 'BazFrame' has different actor isolation from nonisolated superclass 'NotIsolatedPictureFrame'; this is an error in the Swift 6 language mode}}
   init() {
     super.init(size: 0)
   }
@@ -365,7 +365,7 @@ func testSender(
 
   sender.sendAnyArray([sendableObject])
   sender.sendAnyArray([nonSendableObject])
-  // expected-warning@-1 {{conformance of 'NonSendableClass' to 'Sendable' is unavailable; this is an error in Swift 6}}
+  // expected-warning@-1 {{conformance of 'NonSendableClass' to 'Sendable' is unavailable; this is an error in the Swift 6 language mode}}
 
   sender.sendGeneric(sendableGeneric) // no warning
 
@@ -393,7 +393,7 @@ extension SomeWrapper: Sendable where T: Sendable {}
   func makeCall(slowServer: SlowServer) {
     slowServer.doSomethingSlow("churn butter") { (_ : Int) in
       let _ = self.isolatedThing
-      // expected-warning@-1 {{main actor-isolated property 'isolatedThing' can not be referenced from a Sendable closure; this is an error in Swift 6}}
+      // expected-warning@-1 {{main actor-isolated property 'isolatedThing' can not be referenced from a Sendable closure; this is an error in the Swift 6 language mode}}
     }
   }
 }

test/ClangImporter/objc_async_conformance.swift

@@ -87,7 +87,7 @@ class SelectorBothAsync2: NSObject, SelectorBothAsyncProto {
   func hello() async -> Bool // expected-note {{method 'hello()' declared here}}
 
   @objc(helloWithCompletion:)
-  func hello(completion: @escaping (Bool) -> Void) // expected-warning {{method 'hello(completion:)' with Objective-C selector 'helloWithCompletion:' conflicts with method 'hello()' with the same Objective-C selector; this is an error in Swift 6}}
+  func hello(completion: @escaping (Bool) -> Void) // expected-warning {{method 'hello(completion:)' with Objective-C selector 'helloWithCompletion:' conflicts with method 'hello()' with the same Objective-C selector; this is an error in the Swift 6 language mode}}
 }
 
 // additional coverage for situation like C4, where the method names don't

test/ClangImporter/objc_bridging_custom.swift

@@ -161,7 +161,7 @@ protocol TestProto {
 
   @objc optional subscript(a a: Refrigerator) -> Refrigerator? { get } // expected-note 2 {{here}} {{none}}
   @objc optional subscript(generic a: ManufacturerInfo<NSString>) -> ManufacturerInfo<NSString>? { get } // expected-note {{here}} {{none}}
-  // expected-warning@-1 {{subscript getter with Objective-C selector 'objectForKeyedSubscript:' conflicts with previous declaration with the same Objective-C selector; this is an error in Swift 6}}
+  // expected-warning@-1 {{subscript getter with Objective-C selector 'objectForKeyedSubscript:' conflicts with previous declaration with the same Objective-C selector; this is an error in the Swift 6 language mode}}
 
   @objc optional var prop: Refrigerator? { get } // expected-note {{here}} {{none}}
   @objc optional var propGeneric: ManufacturerInfo<NSString>? { get } // expected-note {{here}} {{none}}

test/Concurrency/Inputs/sendable_cycle_other.swift

@@ -1,3 +1,3 @@
 struct Foo {
-  static let member = Bar() // expected-complete-warning {{static property 'member' is not concurrency-safe because it is not either conforming to 'Sendable' or isolated to a global actor; this is an error in Swift 6}}
+  static let member = Bar() // expected-complete-warning {{static property 'member' is not concurrency-safe because it is not either conforming to 'Sendable' or isolated to a global actor; this is an error in the Swift 6 language mode}}
 }

test/Concurrency/actor_inout_isolation.swift

@@ -318,7 +318,7 @@ actor ProtectDictionary {
 
   func invalid() async {
     await dict[0].mutate()
-    // expected-warning@-1 {{cannot call mutating async function 'mutate()' on actor-isolated property 'dict'; this is an error in Swift 6}}
+    // expected-warning@-1 {{cannot call mutating async function 'mutate()' on actor-isolated property 'dict'; this is an error in the Swift 6 language mode}}
     // expected-targeted-complete-warning@-2 {{passing argument of non-sendable type 'inout Optional<Int>' outside of actor-isolated context may introduce data races}}
   }
 }