[PrintAsObjC] Add unavailable attribute to unavailable obj-c initializers (#3852)

* [PrintAsObjC] Add unavailable attribute to non-inherited initializers

Initializers that aren't inherited by subclasses cannot be called, so we
should make this visible to Obj-C.

Due to SR-2211, non-inherited convenience initializers do not get this
same treatment.

* [PrintAsObjC] Add unavailable initializers for private overrides

When a public initializer is overridden with a private one, we need to
mark these as unavailable to Obj-C as they're not supposed to be
callable even though they do exist.

Author: lilyball

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -137,11 +137,19 @@ class ObjCPrinter : private DeclVisitor<ObjCPrinter>,
     visit(const_cast<Decl *>(D));
   }
 
-  bool shouldInclude(const ValueDecl *VD) {
-    return (VD->isObjC() || VD->getAttrs().hasAttribute<CDeclAttr>()) &&
-      VD->getFormalAccess() >= minRequiredAccess &&
-      !(isa<ConstructorDecl>(VD) && 
-        cast<ConstructorDecl>(VD)->hasStubImplementation());
+  bool shouldInclude(const ValueDecl *VD, bool checkParent = true) {
+    if (!(VD->isObjC() || VD->getAttrs().hasAttribute<CDeclAttr>()))
+      return false;
+    if (VD->getFormalAccess() >= minRequiredAccess) {
+      return true;
+    } else if (checkParent) {
+      if (auto ctor = dyn_cast<ConstructorDecl>(VD)) {
+        // Check if we're overriding an initializer that is visible to obj-c
+        if (auto parent = ctor->getOverriddenDecl())
+          return shouldInclude(parent, false);
+      }
+    }
+    return false;
   }
 
 private:
@@ -479,7 +487,12 @@ class ObjCPrinter : private DeclVisitor<ObjCPrinter>,
 
     // Swift designated initializers are Objective-C designated initializers.
     if (auto ctor = dyn_cast<ConstructorDecl>(AFD)) {
-      if (ctor->isDesignatedInit() &&
+      if (ctor->hasStubImplementation()
+          || ctor->getFormalAccess() < minRequiredAccess) {
+        // This will only be reached if the overridden initializer has the
+        // required access
+        os << " SWIFT_UNAVAILABLE";
+      } else if (ctor->isDesignatedInit() &&
           !isa<ProtocolDecl>(ctor->getDeclContext())) {
         os << " OBJC_DESIGNATED_INITIALIZER";
       }
@@ -1961,6 +1974,9 @@ class ModuleWriter {
              "SWIFT_ENUM(_type, _name)\n"
            "# endif\n"
            "#endif\n"
+           "#if !defined(SWIFT_UNAVAILABLE)\n"
+           "# define SWIFT_UNAVAILABLE __attribute__((unavailable))\n"
+           "#endif\n"
            ;
     static_assert(SWIFT_MAX_IMPORTED_SIMD_ELEMENTS == 4,
                 "need to add SIMD typedefs here if max elements is increased");

test/PrintAsObjC/classes.swift

@@ -108,6 +108,8 @@ class ClassWithCustomNameSub : ClassWithCustomName {}
 // CHECK-NEXT: - (nonnull instancetype)initWithString:(NSString * _Nonnull)s boolean:(BOOL)b;
 // CHECK-NEXT: - (nullable instancetype)initWithBoolean:(BOOL)b;
 // CHECK-NEXT: - (nonnull instancetype)initForFun OBJC_DESIGNATED_INITIALIZER;
+// CHECK-NEXT: - (nonnull instancetype)initWithMoreFun OBJC_DESIGNATED_INITIALIZER;
+// CHECK-NEXT: - (nonnull instancetype)initWithEvenMoreFun OBJC_DESIGNATED_INITIALIZER;
 // CHECK-NEXT: @end
 @objc class Initializers {
   init() {}
@@ -120,6 +122,39 @@ class ClassWithCustomNameSub : ClassWithCustomName {}
   convenience init?(boolean b: ObjCBool) { self.init() }
 
   init(forFun: ()) { }
+
+  init(moreFun: ()) { }
+
+  init(evenMoreFun: ()) { }
+}
+
+// CHECK-LABEL: @interface InheritedInitializers
+// CHECK-NEXT: - (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
+// CHECK-NEXT: - (nonnull instancetype)initWithFloat:(float)f SWIFT_UNAVAILABLE;
+// CHECK-NEXT: - (nonnull instancetype)initWithMoreFun SWIFT_UNAVAILABLE;
+// CHECK-NEXT: - (nonnull instancetype)initForFun SWIFT_UNAVAILABLE;
+// CHECK-NEXT: - (nonnull instancetype)initWithEvenMoreFun SWIFT_UNAVAILABLE;
+// CHECK-NEXT: @end
+@objc class InheritedInitializers : Initializers {
+  override init() {
+    super.init()
+  }
+
+  private convenience init(float f: Float) { self.init() }
+
+  private override init(moreFun: ()) { super.init() }
+}
+
+// CHECK-LABEL: @interface InheritedInitializersAgain
+// CHECK-NEXT: - (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
+// CHECK-NEXT: - (nonnull instancetype)initWithEvenMoreFun OBJC_DESIGNATED_INITIALIZER;
+// CHECK-NEXT: @end
+@objc class InheritedInitializersAgain : InheritedInitializers {
+  override init() {
+    super.init()
+  }
+
+  init(evenMoreFun: ()) { super.init() }
 }
 
 // NEGATIVE-NOT: NotObjC

test/PrintAsObjC/protocols.swift

@@ -75,7 +75,8 @@ protocol CustomNameType2 {}
 }
 
 // CHECK-LABEL: @interface MyObject : NSObject <NSCoding>
-// CHECK-NEXT: init
+// CHECK-NEXT: initWithCoder
+// CHECK-NEXT: init SWIFT_UNAVAILABLE
 // CHECK-NEXT: @end
 // NEGATIVE-NOT: @protocol NSCoding
 class MyObject : NSObject, NSCoding {