[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.

Author: lilyball

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -139,9 +139,7 @@ class ObjCPrinter : private DeclVisitor<ObjCPrinter>,
 
   bool shouldInclude(const ValueDecl *VD) {
     return (VD->isObjC() || VD->getAttrs().hasAttribute<CDeclAttr>()) &&
-      VD->getFormalAccess() >= minRequiredAccess &&
-      !(isa<ConstructorDecl>(VD) && 
-        cast<ConstructorDecl>(VD)->hasStubImplementation());
+      VD->getFormalAccess() >= minRequiredAccess;
   }
 
 private:
@@ -479,7 +477,9 @@ 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()) {
+        os << " SWIFT_UNAVAILABLE";
+      } else if (ctor->isDesignatedInit() &&
           !isa<ProtocolDecl>(ctor->getDeclContext())) {
         os << " OBJC_DESIGNATED_INITIALIZER";
       }
@@ -1961,6 +1961,9 @@ 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

@@ -122,6 +122,25 @@ class ClassWithCustomNameSub : ClassWithCustomName {}
   init(forFun: ()) { }
 }
 
+// CHECK-LABEL: @interface InheritedInitializers
+// CHECK-NEXT: - (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
+// CHECK-NEXT: - (nonnull instancetype)initForFun SWIFT_UNAVAILABLE;
+// CHECK-NEXT: @end
+@objc class InheritedInitializers : Initializers {
+  override init() {
+    super.init()
+  }
+}
+
+// CHECK-LABEL: @interface InheritedInitializersAgain
+// CHECK-NEXT: - (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
+// CHECK-NEXT: @end
+@objc class InheritedInitializersAgain : InheritedInitializers {
+  override init() {
+    super.init()
+  }
+}
+
 // NEGATIVE-NOT: NotObjC
 class 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 {