Merge pull request swiftlang#8496 from DougGregor/se-0160-objc-nonobjc-extensions

Author: swift-ci

include/swift/AST/Attr.def

@@ -92,7 +92,7 @@ SIMPLE_DECL_ATTR(final, Final,
                  OnClass | OnFunc | OnVar | OnSubscript|DeclModifier, 2)
 
 DECL_ATTR(objc, ObjC,
-          OnFunc | OnClass | OnProtocol | OnVar | OnSubscript |
+          OnFunc | OnClass | OnProtocol | OnExtension | OnVar | OnSubscript |
           OnConstructor | OnDestructor | OnEnum | OnEnumElement, 3)
 
 SIMPLE_DECL_ATTR(required, Required,
@@ -158,7 +158,7 @@ DECL_ATTR(autoclosure, AutoClosure, OnParam, 28)
 SIMPLE_DECL_ATTR(noescape, NoEscape, OnParam, 29)
 
 SIMPLE_DECL_ATTR(nonobjc, NonObjC,
-                 OnFunc | OnVar | OnSubscript | OnConstructor, 30)
+                 OnExtension | OnFunc | OnVar | OnSubscript | OnConstructor, 30)
 
 SIMPLE_DECL_ATTR(_fixed_layout, FixedLayout,
                  OnVar | OnClass | OnStruct | OnEnum | UserInaccessible, 31)

include/swift/AST/DiagnosticsSema.def

@@ -2983,13 +2983,16 @@ ERROR(invalid_objc_decl_context,none,
       "@objc can only be used with members of classes, @objc protocols, and "
       "concrete extensions of classes", ())
 ERROR(invalid_objc_decl,none,
-      "only classes, protocols, methods, initializers, properties, and "
-      "subscript declarations can be declared @objc", ())
+      "only classes (and their extensions), protocols, methods, initializers, "
+      "properties, and subscript declarations can be declared @objc", ())
 ERROR(invalid_objc_swift_rooted_class,none,
       "only classes that inherit from NSObject can be declared @objc", ())
 ERROR(invalid_nonobjc_decl,none,
       "only methods, initializers, properties and subscript declarations can "
       "be declared @nonobjc", ())
+ERROR(invalid_nonobjc_extension,none,
+      "only extensions of classes can be declared @nonobjc", ())
+
 ERROR(objc_in_extension_context,none,
       "members of constrained extensions cannot be declared @objc", ())
 ERROR(objc_in_generic_extension,none,
@@ -3050,8 +3053,11 @@ ERROR(objc_enum_case_req_objc_enum,none,
 ERROR(objc_enum_case_multi,none,
       "'@objc' enum case declaration defines multiple enum cases with the same Objective-C name", ())
 
+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 @NSManaged|a member of an @objc protocol|implicitly @objc|an @objc override|an implementation of an @objc requirement|marked @IBInspectable|marked @GKInspectable}"
+#define OBJC_ATTR_SELECT "select{marked @_cdecl|marked dynamic|marked @objc|marked @IBOutlet|marked @IBAction|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)}"
 
 ERROR(objc_invalid_on_var,none,
       "property cannot be %" OBJC_ATTR_SELECT "0 "

lib/Sema/TypeCheckDecl.cpp

@@ -2285,6 +2285,15 @@ static void checkAccessibility(TypeChecker &TC, const Decl *D) {
   }
 }
 
+/// Whether this declaration is a member of a class extension marked @objc.
+static bool isMemberOfObjCClassExtension(const ValueDecl *VD) {
+  auto ext = dyn_cast<ExtensionDecl>(VD->getDeclContext());
+  if (!ext) return false;
+
+  return ext->getAsClassOrClassExtensionContext() &&
+    ext->getAttrs().hasAttribute<ObjCAttr>();
+}
+
 /// Whether this declaration is a member of a class with the `@objcMembers`
 /// attribute.
 static bool isMemberOfObjCMembersClass(const ValueDecl *VD) {
@@ -2341,8 +2350,13 @@ static Optional<ObjCReason> shouldMarkAsObjC(TypeChecker &TC,
     return ObjCReason::MemberOfObjCProtocol;
   // A @nonobjc is not @objc, even if it is an override of an @objc, so check
   // for @nonobjc first.
-  if (VD->getAttrs().hasAttribute<NonObjCAttr>())
+  if (VD->getAttrs().hasAttribute<NonObjCAttr>() ||
+      (isa<ExtensionDecl>(VD->getDeclContext()) &&
+       cast<ExtensionDecl>(VD->getDeclContext())->getAttrs()
+        .hasAttribute<NonObjCAttr>()))
     return None;
+  if (isMemberOfObjCClassExtension(VD))
+    return ObjCReason::MemberOfObjCExtension;
   if (isMemberOfObjCMembersClass(VD) && canInferImplicitObjC())
     return ObjCReason::MemberOfObjCMembersClass;
   // An override of an @objc declaration is implicitly @objc.
@@ -8404,6 +8418,9 @@ static void validateAttributes(TypeChecker &TC, Decl *D) {
     if (isa<ClassDecl>(D) ||
         isa<ProtocolDecl>(D)) {
       /* ok */
+    } else if (auto Ext = dyn_cast<ExtensionDecl>(D)) {
+      if (!Ext->getAsClassOrClassExtensionContext())
+        error = diag::objc_extension_not_class;
     } else if (auto ED = dyn_cast<EnumDecl>(D)) {
       if (ED->isGenericContext())
         error = diag::objc_enum_generic;
@@ -8501,7 +8518,8 @@ static void validateAttributes(TypeChecker &TC, Decl *D) {
   }
 
   if (auto nonObjcAttr = Attrs.getAttribute<NonObjCAttr>()) {
-    // Only methods, properties, subscripts and constructors can be NonObjC.
+    // Only extensions of classes; methods, properties, subscripts
+    // and constructors can be NonObjC.
     // The last three are handled automatically by generic attribute
     // validation -- for the first one, we have to check FuncDecls
     // ourselves.
@@ -8515,6 +8533,11 @@ static void validateAttributes(TypeChecker &TC, Decl *D) {
       error = diag::invalid_nonobjc_decl;
     }
 
+    if (auto ext = dyn_cast<ExtensionDecl>(D)) {
+      if (!ext->getAsClassOrClassExtensionContext())
+        error = diag::invalid_nonobjc_extension;
+    }
+
     if (error) {
       TC.diagnose(D->getStartLoc(), *error)
         .fixItRemove(nonObjcAttr->getRangeWithAt());

lib/Sema/TypeChecker.h

@@ -539,6 +539,8 @@ enum class ObjCReason {
   ExplicitlyIBInspectable,
   /// Has an explicit '@GKInspectable' attribute.
   ExplicitlyGKInspectable,
+  /// Is it a member of an @objc extension of a class.
+  MemberOfObjCExtension,
   /// Is it a member of an @objcMembers class.
   MemberOfObjCMembersClass,
   /// A member of an Objective-C-defined class or subclass.
@@ -547,7 +549,8 @@ enum class ObjCReason {
   Accessor,
 };
 
-/// Determine whether we should diagnose conflicts due yo
+/// Determine whether we should diagnose conflicts due to inferring @objc
+/// with this particular reason.
 static inline bool shouldDiagnoseObjCReason(ObjCReason reason) {
   switch(reason) {
   case ObjCReason::ExplicitlyCDecl:
@@ -562,6 +565,7 @@ static inline bool shouldDiagnoseObjCReason(ObjCReason reason) {
   case ObjCReason::ImplicitlyObjC:
   case ObjCReason::ExplicitlyIBInspectable:
   case ObjCReason::ExplicitlyGKInspectable:
+  case ObjCReason::MemberOfObjCExtension:
     return true;
 
   case ObjCReason::MemberOfObjCSubclass:
@@ -587,6 +591,7 @@ static inline unsigned getObjCDiagnosticAttrKind(ObjCReason reason) {
   case ObjCReason::ImplicitlyObjC:
   case ObjCReason::ExplicitlyIBInspectable:
   case ObjCReason::ExplicitlyGKInspectable:
+  case ObjCReason::MemberOfObjCExtension:
     return static_cast<unsigned>(reason);
 
   case ObjCReason::MemberOfObjCSubclass:

test/attr/attr_nonobjc.swift

@@ -102,3 +102,6 @@ class NSManagedAndNonObjCNotAllowed {
     }
   }
 }
+
+struct SomeStruct { }
+@nonobjc extension SomeStruct { } // expected-error{{only extensions of classes can be declared @nonobjc}}

test/attr/attr_objc.swift

@@ -30,7 +30,7 @@ protocol Protocol_Class2 : class {}
 
 //===--- Subjects of @objc attribute.
 
-@objc extension PlainClass { } // expected-error{{@objc cannot be applied to this declaration}}{{1-7=}}
+@objc extension PlainStruct { } // expected-error{{'@objc' can only be applied to an extension of a class}}{{1-7=}}
 
 @objc  
 var subject_globalVar: Int // expected-error {{@objc can only be used with members of classes, @objc protocols, and concrete extensions of classes}}
@@ -2159,6 +2159,17 @@ class ConformsToProtocolThrowsObjCName2 : ProtocolThrowsObjCName {
   @objc func func_dictionary2b(x: Dictionary<String, Int>) { }
 }
 
+@objc extension PlainClass {
+  // CHECK-LABEL: @objc final func objc_ext_objc_okay(_: Int) {
+  final func objc_ext_objc_okay(_: Int) { }
+
+  final func objc_ext_objc_not_okay(_: PlainStruct) { }
+  // expected-error@-1{{method cannot be in an @objc extension of a class (without @nonobjc) because the type of the parameter cannot be represented in Objective-C}}
+  // expected-note@-2 {{Swift structs cannot be represented in Objective-C}}
+
+  // CHECK-LABEL: {{^}} @nonobjc final func objc_ext_objc_explicit_nonobjc(_: PlainStruct) {
+  @nonobjc final func objc_ext_objc_explicit_nonobjc(_: PlainStruct) { }
+}
 
 @objc class ObjC_Class1 : Hashable { 
   var hashValue: Int { return 0 }

test/attr/attr_objcMembers.swift

@@ -31,3 +31,11 @@ func selectorTest() {
   _ = #selector(SubClassOfSomeClassWithObjCMembers.baz)
   _ = #selector(SubClassOfSomeClassWithObjCMembers.wibble)
 }
+
+@nonobjc extension SomeClassWithObjCMembers {
+  func notInferredObjC() { } // expected-note{{add '@objc' to expose this instance method to Objective-C}}
+}
+
+func selectorTestFail() {
+  _ = #selector(SomeClassWithObjCMembers.notInferredObjC) // expected-error{{argument of '#selector' refers to instance method 'notInferredObjC()' that is not exposed to Objective-C}}
+}