Sema: Downgrade nonisolated lazy error to warning until -swift-version 6

Fixes rdar://139238003.

Author: slavapestov

lib/Sema/TypeCheckAttr.cpp

@@ -7274,7 +7274,7 @@ void AttributeChecker::visitNonisolatedAttr(NonisolatedAttr *attr) {
 
     if (var->getAttrs().hasAttribute<LazyAttr>()) {
       diagnoseAndRemoveAttr(attr, diag::nonisolated_lazy)
-        .warnUntilSwiftVersionIf(attr->isImplicit(), 6);
+        .warnUntilSwiftVersion(6);
       return;
     }
 

test/Concurrency/actor_isolation.swift

@@ -834,29 +834,29 @@ actor LazyActor {
     lazy var l25: Int = { [unowned self] in self.l }()
 
     nonisolated lazy var l31: Int = { v }()
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     // expected-warning@-2 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l32: Int = v
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l33: Int = { self.v }()
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     // expected-warning@-2 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l34: Int = self.v
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l35: Int = { [unowned self] in self.v }()
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     // expected-warning@-2 {{actor-isolated default value in a nonisolated context; this is an error in the Swift 6 language mode}}
 
     nonisolated lazy var l41: Int = { l }()
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l42: Int = l
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l43: Int = { self.l }()
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l44: Int = self.l
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
     nonisolated lazy var l45: Int = { [unowned self] in self.l }()
-    // expected-error@-1 {{'nonisolated' is not supported on lazy properties}}
+    // expected-warning@-1 {{'nonisolated' is not supported on lazy properties; this is an error in the Swift 6 language mode}}
 }
 
 // Infer global actors from context only for instance members.