Ban @objcMembers Without Importing Foundation

rdar://98734024

Author: CodaFi

include/swift/AST/DiagnosticsSema.def

@@ -5238,7 +5238,7 @@ ERROR(objc_extension_not_class,none,
       "'@objc' can only be applied to an extension of a class", ())
 
 // If you change this, also change enum ObjCReason
-#define OBJC_ATTR_SELECT "select{marked @_cdecl|marked dynamic|marked @objc|marked @IBOutlet|marked @IBAction|marked @IBSegueAction|marked @NSManaged|a member of an @objc protocol|implicitly @objc|an @objc override|an implementation of an @objc requirement|marked @IBInspectable|marked @GKInspectable|in an @objc extension of a class (without @nonobjc)|marked @objc by an access note}"
+#define OBJC_ATTR_SELECT "select{marked @_cdecl|marked dynamic|marked @objc|marked @objcMembers|marked @IBOutlet|marked @IBAction|marked @IBSegueAction|marked @NSManaged|a member of an @objc protocol|implicitly @objc|an @objc override|an implementation of an @objc requirement|marked @IBInspectable|marked @GKInspectable|in an @objc extension of a class (without @nonobjc)|marked @objc by an access note}"
 
 WARNING(attribute_meaningless_when_nonobjc,none,
         "'@%0' attribute is meaningless on a property that cannot be "

lib/Sema/TypeCheckAttr.cpp

@@ -1147,9 +1147,11 @@ static bool checkObjCDeclContext(Decl *D) {
   return false;
 }
 
-static void diagnoseObjCAttrWithoutFoundation(ObjCAttr *attr, Decl *decl,
+static void diagnoseObjCAttrWithoutFoundation(DeclAttribute *attr, Decl *decl,
                                               ObjCReason reason,
                                               DiagnosticBehavior behavior) {
+  assert(attr->getKind() == DeclAttrKind::DAK_ObjC ||
+         attr->getKind() == DeclAttrKind::DAK_ObjCMembers);
   auto *SF = decl->getDeclContext()->getParentSourceFile();
   assert(SF);
 
@@ -1369,6 +1371,10 @@ void AttributeChecker::visitNonObjCAttr(NonObjCAttr *attr) {
 void AttributeChecker::visitObjCMembersAttr(ObjCMembersAttr *attr) {
   if (!isa<ClassDecl>(D))
     diagnoseAndRemoveAttr(attr, diag::objcmembers_attribute_nonclass);
+
+  auto reason = ObjCReason(ObjCReason::ExplicitlyObjCMembers, attr);
+  auto behavior = behaviorLimitForObjCReason(reason, Ctx);
+  diagnoseObjCAttrWithoutFoundation(attr, D, reason, behavior);
 }
 
 void AttributeChecker::visitOptionalAttr(OptionalAttr *attr) {

lib/Sema/TypeCheckDeclObjC.cpp

@@ -37,6 +37,7 @@ swift::behaviorLimitForObjCReason(ObjCReason reason, ASTContext &ctx) {
   case ObjCReason::ExplicitlyCDecl:
   case ObjCReason::ExplicitlyDynamic:
   case ObjCReason::ExplicitlyObjC:
+  case ObjCReason::ExplicitlyObjCMembers:
   case ObjCReason::ExplicitlyIBOutlet:
   case ObjCReason::ExplicitlyIBAction:
   case ObjCReason::ExplicitlyIBSegueAction:
@@ -71,6 +72,7 @@ unsigned swift::getObjCDiagnosticAttrKind(ObjCReason reason) {
   case ObjCReason::ExplicitlyCDecl:
   case ObjCReason::ExplicitlyDynamic:
   case ObjCReason::ExplicitlyObjC:
+  case ObjCReason::ExplicitlyObjCMembers:
   case ObjCReason::ExplicitlyIBOutlet:
   case ObjCReason::ExplicitlyIBAction:
   case ObjCReason::ExplicitlyIBSegueAction:
@@ -128,6 +130,7 @@ void ObjCReason::describe(const Decl *D) const {
   case ObjCReason::ExplicitlyCDecl:
   case ObjCReason::ExplicitlyDynamic:
   case ObjCReason::ExplicitlyObjC:
+  case ObjCReason::ExplicitlyObjCMembers:
   case ObjCReason::ExplicitlyIBOutlet:
   case ObjCReason::ExplicitlyIBAction:
   case ObjCReason::ExplicitlyIBSegueAction:

lib/Sema/TypeCheckObjC.h

@@ -49,6 +49,8 @@ class ObjCReason {
     ExplicitlyDynamic,
     /// Has an explicit '@objc' attribute.
     ExplicitlyObjC,
+    /// Has an explicit '@objcmembers' attribute.
+    ExplicitlyObjCMembers,
     /// Has an explicit '@IBOutlet' attribute.
     ExplicitlyIBOutlet,
     /// Has an explicit '@IBAction' attribute.
@@ -101,6 +103,7 @@ class ObjCReason {
     case ExplicitlyCDecl:
     case ExplicitlyDynamic:
     case ExplicitlyObjC:
+    case ExplicitlyObjCMembers:
     case ExplicitlyIBOutlet:
     case ExplicitlyIBAction:
     case ExplicitlyIBSegueAction:

test/Sema/objcmembers_attr_requires_module.swift

@@ -0,0 +1,6 @@
+// RUN: %target-swift-frontend -typecheck -verify -enable-objc-interop %s
+// RUN: %target-swift-frontend -typecheck -verify -enable-objc-interop %s -parse-as-library
+
+@objcMembers class Oof {
+  // expected-error@-1 {{@objcMembers attribute used without importing module 'Foundation'}}
+}