Respect @preconcurrency in check of nonisoalted let variables

(cherry picked from commit fc85f98)

Author: DougGregor

lib/Sema/TypeCheckAttr.cpp

@@ -6948,13 +6948,16 @@ void AttributeChecker::visitNonisolatedAttr(NonisolatedAttr *attr) {
 
       // 'nonisolated' without '(unsafe)' is not allowed on non-Sendable variables.
       auto type = var->getTypeInContext();
-      if (!attr->isUnsafe() && !type->hasError() &&
-          !type->isSendableType()) {
-        Ctx.Diags.diagnose(attr->getLocation(),
-                           diag::nonisolated_non_sendable,
-                           type)
-          .warnUntilSwiftVersion(6);
-        return;
+      if (!attr->isUnsafe() && !type->hasError()) {
+        bool diagnosed = diagnoseIfAnyNonSendableTypes(
+            type,
+            SendableCheckContext(dc),
+            Type(),
+            SourceLoc(),
+            attr->getLocation(),
+            diag::nonisolated_non_sendable);
+        if (diagnosed)
+          return;
       }
 
       if (auto nominal = dyn_cast<NominalTypeDecl>(dc)) {

test/Concurrency/concurrent_value_checking.swift

@@ -215,7 +215,7 @@ func testUnsafeSendableInAsync() async {
 // ----------------------------------------------------------------------
 // Sendable restriction on key paths.
 // ----------------------------------------------------------------------
-class NC: Hashable { // expected-note 2{{class 'NC' does not conform to the 'Sendable' protocol}}
+class NC: Hashable { // expected-note 3{{class 'NC' does not conform to the 'Sendable' protocol}}
   func hash(into: inout Hasher) { }
   static func==(_: NC, _: NC) -> Bool { true }
 }

test/Concurrency/global_variables.swift

@@ -23,7 +23,7 @@ final class TestSendable: Sendable {
   init() {}
 }
 
-final class TestNonsendable { // expected-note 2{{class 'TestNonsendable' does not conform to the 'Sendable' protocol}}
+final class TestNonsendable { // expected-note 3{{class 'TestNonsendable' does not conform to the 'Sendable' protocol}}
   init() {}
 }
 

test/Concurrency/predates_concurrency_import.swift

@@ -41,3 +41,13 @@ extension NonStrictClass {
 extension StrictStruct {
   @Sendable func f() { } // expected-warning{{instance method of non-Sendable type 'StrictStruct' cannot be marked as '@Sendable'}}
 }
+
+
+struct HasStatics {
+  nonisolated static let ns: NonStrictClass = NonStrictClass()
+
+  nonisolated static let ss: StrictStruct = StrictStruct()
+  // expected-warning@-1{{'nonisolated' can not be applied to variable with non-'Sendable' type 'StrictStruct'}}
+  // expected-warning@-2{{static property 'ss' is not concurrency-safe because non-'Sendable' type 'StrictStruct' may have shared mutable state}}
+  // expected-note@-3{{isolate 'ss' to a global actor, or conform 'StrictStruct' to 'Sendable'}}
+}