[Clang importer] Don't prefix-strip notification names.

Author: DougGregor

lib/ClangImporter/ClangImporter.cpp

@@ -2318,18 +2318,25 @@ static clang::SwiftNameAttr *findSwiftNameAttr(const clang::Decl *decl,
 
 /// Prepare global name for importing onto a swift_newtype.
 static StringRef determineSwiftNewtypeBaseName(StringRef baseName,
-                                               StringRef newtypeName) {
-  baseName = stripLeadingK(baseName);
-
-  bool nonIdentifier = false;
-  auto pre = getCommonWordPrefix(newtypeName, baseName, nonIdentifier);
-  if (pre.size())
-    baseName = baseName.drop_front(pre.size());
+                                               StringRef newtypeName,
+                                               bool &strippedPrefix) {
+  StringRef newBaseName = stripLeadingK(baseName);
+  if (newBaseName != baseName) {
+    baseName = newBaseName;
+    strippedPrefix = true;
+  }
 
   // Special case: Strip Notification for NSNotificationName
   auto stripped = stripNotification(baseName);
   if (!stripped.empty())
-    baseName = stripped;
+    return stripped;
+
+  bool nonIdentifier = false;
+  auto pre = getCommonWordPrefix(newtypeName, baseName, nonIdentifier);
+  if (pre.size()) {
+    baseName = baseName.drop_front(pre.size());
+    strippedPrefix = true;
+  }
 
   return baseName;
 }
@@ -2822,8 +2829,8 @@ auto ClangImporter::Implementation::importFullName(
   // swift_newtype-ed declarations may have common words with the type name
   // stripped.
   if (auto newtypeDecl = findSwiftNewtype(D, clangSema, swift2Name)) {
-    baseName = determineSwiftNewtypeBaseName(baseName, newtypeDecl->getName());
-    strippedPrefix = true;
+    baseName = determineSwiftNewtypeBaseName(baseName, newtypeDecl->getName(),
+                                             strippedPrefix);
   }
 
   if (!result.isSubscriptAccessor() && !swift2Name) {

test/IDE/Inputs/custom-modules/Newtype.h

@@ -40,6 +40,7 @@ extern NSURLResourceKey const NSURLLocalizedNameKey;
 // Special case: Notifications
 extern const NSString *FooNotification;
 extern const NSString *kBarNotification;
+extern const NSString *NSWibbleNotification;
 
 // But not just 'Notification'
 extern const NSString *kNotification;

test/IDE/newtype.swift

@@ -54,8 +54,9 @@
 // PRINT-NEXT:    static let localizedNameKey: NSURLResourceKey
 // PRINT-NEXT:  }
 // PRINT-NEXT:  extension NSNotificationName {
-// PRINT-NEXT:    static let foo: NSNotificationName
+// PRINT-NEXT:    static let Foo: NSNotificationName
 // PRINT-NEXT:    static let bar: NSNotificationName
+// PRINT-NEXT:    static let NSWibble: NSNotificationName
 // PRINT-NEXT:  }
 // PRINT-NEXT:  let kNotification: String
 // PRINT-NEXT:  let Notification: String
@@ -79,7 +80,7 @@ func tests() {
 	let _ = ErrorDomain(rawValue: thirdEnum.rawValue!)
 	let _ = ClosedEnum(rawValue: errOne.rawValue)
 
-	let _ = NSNotificationName.foo
+	let _ = NSNotificationName.Foo
 	let _ = NSNotificationName.bar
 }
 

test/IRGen/newtype.swift

@@ -14,7 +14,7 @@ public func getErrorDomain() -> ErrorDomain {
 
 // CHECK-LABEL: _TF7newtype6getFooFT_VSC18NSNotificationName
 public func getFoo() -> NSNotificationName {
-  return NSNotificationName.foo
+  return NSNotificationName.Foo
   // CHECK: load {{.*}} @FooNotification
   // CHECK: ret
 }