[ObjC Interop] Map Swift @objc properties named isFoo to ObjC Cocoa conventions

The Objective-C Cocoa convention eschew "is" on property names, but
use it on the getter, while the Swift API guidelines state that
Boolean properties should read as assertions (e.g., "isEmpty" rather
than "empty"). Map Swift properties named "isFoo" to Objective-C by
removing the "is" from the resulting Objective-C property name (so it
will be named "foo") and from the setter (which will have the
Objective-C selector "setFoo:") while retaining the "is" for the
getter selector ("isFoo").

Fixes rdar://problem/17090661.

Author: DougGregor

include/swift/AST/Decl.h

@@ -4141,11 +4141,6 @@ class VarDecl : public AbstractStorageDecl {
   /// Return the Objective-C runtime name for this property.
   Identifier getObjCPropertyName() const;
 
-  /// Retrieve the default Objective-C selector for the getter of a
-  /// property of the given name.
-  static ObjCSelector getDefaultObjCGetterSelector(ASTContext &ctx,
-                                                   Identifier propertyName);
-
   /// Retrieve the default Objective-C selector for the setter of a
   /// property of the given name.
   static ObjCSelector getDefaultObjCSetterSelector(ASTContext &ctx,

lib/AST/Decl.cpp

@@ -2936,9 +2936,15 @@ ObjCSelector AbstractStorageDecl::getObjCGetterSelector(
     }
   }
 
-  // The getter selector is the property name itself.
+  // If the Swift name starts with the word "is", use that Swift name as the
+  // getter name.
   auto var = cast<VarDecl>(this);
-  return VarDecl::getDefaultObjCGetterSelector(ctx, var->getObjCPropertyName());
+  if (ctx.LangOpts.OmitNeedlessWords &&
+      camel_case::getFirstWord(var->getName().str()) == "is")
+    return ObjCSelector(ctx, 0, { var->getName() });
+
+  // The getter selector is the property name itself.
+  return ObjCSelector(ctx, 0, { var->getObjCPropertyName() });
 }
 
 ObjCSelector AbstractStorageDecl::getObjCSetterSelector(
@@ -3217,21 +3223,26 @@ Identifier VarDecl::getObjCPropertyName() const {
       return name->getSelectorPieces()[0];
   }
 
-  return getName();
-}
+  // If the Swift property name starts with the word "is", strip the
+  // "is" and lowercase the rest when forming the Objective-C property
+  // name.
+  ASTContext &ctx = getASTContext();
+  StringRef nameStr = getName().str();
+  if (ctx.LangOpts.OmitNeedlessWords &&
+      camel_case::getFirstWord(nameStr) == "is") {
+    SmallString<16> scratch;
+    return ctx.getIdentifier(camel_case::toLowercaseWord(nameStr.substr(2),
+                                                         scratch));
+  }
 
-ObjCSelector VarDecl::getDefaultObjCGetterSelector(ASTContext &ctx,
-                                                   Identifier propertyName) {
-  return ObjCSelector(ctx, 0, propertyName);
+  return getName();
 }
 
-
 ObjCSelector VarDecl::getDefaultObjCSetterSelector(ASTContext &ctx,
                                                    Identifier propertyName) {
   llvm::SmallString<16> scratch;
   scratch += "set";
   camel_case::appendSentenceCase(scratch, propertyName.str());
-
   return ObjCSelector(ctx, 1, ctx.getIdentifier(scratch));
 }
 

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -587,8 +587,7 @@ class ObjCPrinter : private DeclVisitor<ObjCPrinter>,
     // Handle custom accessor names.
     llvm::SmallString<64> buffer;
     if (hasReservedName ||
-        VD->getObjCGetterSelector() !=
-          VarDecl::getDefaultObjCGetterSelector(ctx, objCName)) {
+        VD->getObjCGetterSelector() != ObjCSelector(ctx, 0, { objCName })) {
       os << ", getter=" << VD->getObjCGetterSelector().getString(buffer);
     }
     if (VD->isSettable(nullptr)) {

test/PrintAsObjC/classes.swift

@@ -6,15 +6,15 @@
 // RUN: mkdir %t
 
 // FIXME: BEGIN -enable-source-import hackaround
-// RUN:  %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t  %S/../Inputs/clang-importer-sdk/swift-modules/ObjectiveC.swift
-// RUN:  %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t  %S/../Inputs/clang-importer-sdk/swift-modules/CoreGraphics.swift
-// RUN:  %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t  %S/../Inputs/clang-importer-sdk/swift-modules/Foundation.swift
-// RUN:  %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t  %S/../Inputs/clang-importer-sdk/swift-modules/AppKit.swift
+// RUN:  %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t -enable-omit-needless-words %S/../Inputs/clang-importer-sdk/swift-modules/ObjectiveC.swift
+// RUN:  %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t -enable-omit-needless-words  %S/../Inputs/clang-importer-sdk/swift-modules/CoreGraphics.swift
+// RUN:  %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t -enable-omit-needless-words  %S/../Inputs/clang-importer-sdk/swift-modules/Foundation.swift
+// RUN:  %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t -enable-omit-needless-words  %S/../Inputs/clang-importer-sdk/swift-modules/AppKit.swift
 // FIXME: END -enable-source-import hackaround
 
 
-// RUN: %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t %s -disable-objc-attr-requires-foundation-module
-// RUN: %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -parse-as-library %t/classes.swiftmodule -parse -emit-objc-header-path %t/classes.h -import-objc-header %S/../Inputs/empty.h -disable-objc-attr-requires-foundation-module
+// RUN: %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t %s -enable-omit-needless-words -disable-objc-attr-requires-foundation-module
+// RUN: %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -parse-as-library -enable-omit-needless-words %t/classes.swiftmodule -parse -emit-objc-header-path %t/classes.h -import-objc-header %S/../Inputs/empty.h -disable-objc-attr-requires-foundation-module
 // RUN: FileCheck %s < %t/classes.h
 // RUN: FileCheck --check-prefix=NEGATIVE %s < %t/classes.h
 // RUN: %check-in-clang %t/classes.h
@@ -91,8 +91,11 @@ class ClassWithCustomNameSub : ClassWithCustomName {}
 // CHECK-NEXT: @end
 @objc class ClassWithNSObjectProtocol : NSObjectProtocol {
   var description: String { return "me" }
-  func conformsToProtocol(_: Protocol) -> Bool { return false }
-  func isKindOfClass(aClass: AnyClass) -> Bool { return false }
+  @objc(conformsToProtocol:)
+  func conforms(to _: Protocol) -> Bool { return false }
+
+  @objc(isKindOfClass:)
+  func isKind(of aClass: AnyClass) -> Bool { return false }
 }
 
 // CHECK-LABEL: @interface Initializers
@@ -236,7 +239,7 @@ typealias AliasForNSRect = NSRect
   func emptyArray() -> NSArray { return NSArray() }
   func maybeArray() -> NSArray? { return nil }
 
-  func someEnum() -> NSRuncingMode { return .Mince }
+  func someEnum() -> NSRuncingMode { return .mince }
 
   func zone() -> NSZone { return nil }
 
@@ -394,6 +397,7 @@ public class NonObjCClass { }
 // CHECK-NEXT: + (double)staticDouble;
 // CHECK-NEXT: @property (nonatomic, strong) Properties * _Nullable wobble;
 // CHECK-NEXT: @property (nonatomic, getter=isEnabled, setter=setIsEnabled:) BOOL enabled;
+// CHECK-NEXT: @property (nonatomic, getter=isAnimated) BOOL animated;
 // CHECK-NEXT: @property (nonatomic, getter=register, setter=setRegister:) BOOL register_;
 // CHECK-NEXT: @property (nonatomic, readonly, strong, getter=this) Properties * _Nonnull this_;
 // CHECK-NEXT: init
@@ -425,15 +429,15 @@ public class NonObjCClass { }
 
   weak var weakProto: MyProtocol?
   weak var weakCF: CFTypeRef?
-  weak var weakCFString: CFStringRef?
+  weak var weakCFString: CFString?
 
   typealias CFTypeRefAlias = CFTypeRef
 
   var strongCF: CFTypeRef?
   var strongCFAlias: CFTypeRefAlias?
 
   var anyCF: CFAliasForType?
-  var anyCF2: CFAliasForTypeRef?
+  var anyCF2: CFAliasForType?
 
   @IBOutlet weak var outlet: AnyObject!
   @IBOutlet var typedOutlet: Properties!
@@ -468,6 +472,8 @@ public class NonObjCClass { }
     @objc(setIsEnabled:) set { }
   }
 
+  var isAnimated: Bool = true
+
   var register: Bool = false
   var this: Properties { return self }
 }