[Omit Needless Words] Don't remove a first argument label when the parameter has as default argument.

Parameters that have default arguments should have argument labels;
don't remove them on import. Fixes rdar://problem/26611977.

Author: DougGregor

lib/Basic/StringExtras.cpp

@@ -1254,6 +1254,7 @@ bool swift::omitNeedlessWords(StringRef &baseName,
     NameRole role = i > 0 ? NameRole::SubsequentParameter
       : argNames[0].empty() ? NameRole::BaseName
       : baseName == "init" ? NameRole::SubsequentParameter
+      : paramTypes[0].hasDefaultArgument() ? NameRole::SubsequentParameter
       : NameRole::FirstParameter;
 
     // Omit needless words from the name.

stdlib/public/SDK/Foundation/NSStringAPI.swift

@@ -1415,12 +1415,19 @@ extension String {
   //     stringByFoldingWithOptions:(NSStringCompareOptions)options
   //     locale:(NSLocale *)locale
 
+  @available(*, unavailable, renamed: "folding(options:locale:)")
+  public func folding(
+    _ options: NSStringCompareOptions = [], locale: NSLocale?
+  ) -> String {
+    return folding(options: options, locale: locale)
+  }
+
   /// Returns a string with the given character folding options
   /// applied.
   public func folding(
-    _ options: NSStringCompareOptions = [], locale: NSLocale?
+    options: NSStringCompareOptions = [], locale: NSLocale?
   ) -> String {
-    return _ns.folding(options, locale: locale)
+    return _ns.folding(options: options, locale: locale)
   }
 
   // - (NSString *)stringByPaddingToLength:(NSUInteger)newLength
@@ -1884,13 +1891,6 @@ extension String {
     fatalError("unavailable function can't be called")
   }
 
-  @available(*, unavailable, renamed: "folding(_:locale:)")
-  public func folding(
-    options: NSStringCompareOptions = [], locale: NSLocale?
-  ) -> String {
-    fatalError("unavailable function can't be called")
-  }
-
   @available(*, unavailable, renamed: "padding(toLength:with:startingAt:)")
   public func byPaddingToLength(
     _ newLength: Int, withString padString: String, startingAt padIndex: Int

test/1_stdlib/NSStringAPI.swift

@@ -1391,12 +1391,12 @@ NSStringAPIs.test("deletingLastPathComponent") {
   expectEqual("/tmp", "/tmp/a.txt".deletingLastPathComponent)
 }
 
-NSStringAPIs.test("folding(_:locale:)") {
+NSStringAPIs.test("folding(options:locale:)") {
 
   func fwo(
     _ s: String, _ options: NSStringCompareOptions
   ) -> (NSLocale?) -> String {
-    return { loc in s.folding(options, locale: loc) }
+    return { loc in s.folding(options: options, locale: loc) }
   }
 
   expectLocalizedEquality("abcd", fwo("abCD", .caseInsensitiveSearch), "en")

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

@@ -7,6 +7,11 @@
 @interface SEGreebieArray : NSObject
 @end
 
+typedef NS_OPTIONS(NSUInteger, OMWWobbleOptions) {
+  OMWWobbleSideToSide = 0x01,
+  OMWWobbleBackAndForth = 0x02
+};
+
 @interface OmitNeedlessWords : NSObject
 -(void)jumpToUrl:(nonnull NSURL *)url;
 -(BOOL)objectIsCompatibleWithObject:(nonnull id)other;
@@ -35,6 +40,7 @@
 +(nonnull OmitNeedlessWords *)currentOmitNeedlessWords;
 +(void)setCurrentOmitNeedlessWords:(nonnull OmitNeedlessWords *)value;
 -(void)compilerPlugInValue:(NSInteger)value;
+-(void)wobbleWithOptions:(OMWWobbleOptions)options;
 @end
 
 @interface ABCDoodle : NSObject

test/IDE/print_omit_needless_words.swift

@@ -78,7 +78,7 @@
 // CHECK-FOUNDATION: var isMakingHoney: Bool
 
 // Note: multi-word enum name matching; "with" splits the first piece.
-// CHECK-FOUNDATION: func someMethod(_: DeprecatedOptions = [])
+// CHECK-FOUNDATION: func someMethod(deprecatedOptions: DeprecatedOptions = [])
 
 // Note: class name matching; don't drop "With".
 // CHECK-FOUNDATION: class func withString(_: String!) -> Self!
@@ -135,10 +135,10 @@
 
 // Note: usingBlock -> body
 // CHECK-FOUNDATION: func enumerateObjects(_: ((AnyObject?, Int, UnsafeMutablePointer<ObjCBool>?) -> Void)!)
-// CHECK-FOUNDATION: func enumerateObjects(_: EnumerationOptions = [], using: ((AnyObject?, Int, UnsafeMutablePointer<ObjCBool>?) -> Void)!)
+// CHECK-FOUNDATION: func enumerateObjects(options: EnumerationOptions = [], using: ((AnyObject?, Int, UnsafeMutablePointer<ObjCBool>?) -> Void)!)
 
 // Note: WithBlock -> body, nullable closures default to nil.
-// CHECK-FOUNDATION: func enumerateObjectsRandomly(_: ((AnyObject?, Int, UnsafeMutablePointer<ObjCBool>?) -> Void)? = nil)
+// CHECK-FOUNDATION: func enumerateObjectsRandomly(block: ((AnyObject?, Int, UnsafeMutablePointer<ObjCBool>?) -> Void)? = nil)
 
 // Note: id<Proto> treated as "Proto".
 // CHECK-FOUNDATION: func doSomething(with: Copying)
@@ -311,6 +311,10 @@
 // Don't split "PlugIn".
 // CHECK-OMIT-NEEDLESS-WORDS: func compilerPlugInValue(_: Int)
 
+// Don't strip away argument label completely when there is a default
+// argument.
+// CHECK-OMIT-NEEDLESS-WORDS: func wobble(options: OMWWobbleOptions = [])
+
 // Property-name sensitivity in the base name "Self" stripping.
 // CHECK-OMIT-NEEDLESS-WORDS: func addDoodle(_: ABCDoodle)