Name and label changes for closure parameters (for review only) (#2981)

Implement SE-0118 Name and label changes for closure parameters

[SE-0118](https://github.com/apple/swift-evolution/blob/master/proposals/0118-closure-parameter-names-and-labels.md)

Author: Dave Abrahams

benchmark/single-source/CaptureProp.swift

@@ -21,7 +21,7 @@ func benchCaptureProp<S : Sequence
 
   var it = s.makeIterator()
   let initial = it.next()!
-  return IteratorSequence(it).reduce(initial, combine: f)
+  return IteratorSequence(it).reduce(initial, f)
 }
 
 public func run_CaptureProp(_ N: Int) {

benchmark/single-source/MapReduce.swift

@@ -20,7 +20,7 @@ public func run_MapReduce(_ N: Int) {
   var c = 0
   for _ in 1...N*100 {
     numbers = numbers.map({$0 &+ 5})
-    c += numbers.reduce(0, combine: &+)
+    c += numbers.reduce(0, &+)
   }
   CheckResults(c != 0, "IncorrectResults in MapReduce")
 }

benchmark/single-source/SortStrings.swift

@@ -1021,7 +1021,7 @@ func benchSortStrings(_ words: [String]) {
   // Notice that we _copy_ the array of words before we sort it.
   // Pass an explicit '<' predicate to benchmark reabstraction thunks.
   var tempwords = words
-  tempwords.sort(isOrderedBefore: <)
+  tempwords.sort(by: <)
 }
 
 public func run_SortStrings(_ N: Int) {

stdlib/private/StdlibCollectionUnittest/LoggingWrappers.swift.gyb

@@ -229,10 +229,10 @@ public struct ${Self}<
   }
 
   public func filter(
-    _ includeElement: @noescape (Base.Iterator.Element) throws -> Bool
+    _ isIncluded: @noescape (Base.Iterator.Element) throws -> Bool
   ) rethrows -> [Base.Iterator.Element] {
     Log.filter[selfType] += 1
-    return try base.filter(includeElement)
+    return try base.filter(isIncluded)
   }
 
   public func forEach(
@@ -274,13 +274,13 @@ public struct ${Self}<
   public func split(
     maxSplits: Int = Int.max,
     omittingEmptySubsequences: Bool = true,
-    isSeparator: @noescape (Base.Iterator.Element) throws -> Bool
+    whereSeparator isSeparator: @noescape (Base.Iterator.Element) throws -> Bool
   ) rethrows -> [SubSequence] {
     Log.split[selfType] += 1
     return try base.split(
       maxSplits: maxSplits,
       omittingEmptySubsequences: omittingEmptySubsequences,
-      isSeparator: isSeparator)
+      whereSeparator: isSeparator)
   }
 
   public func _customContainsEquatableElement(

stdlib/private/StdlibUnittest/RaceTest.swift

@@ -596,7 +596,9 @@ internal struct ClosureBasedRaceTest : RaceTestWithPerTrialData {
   ) {}
 }
 
-public func runRaceTest(trials: Int, threads: Int? = nil, body: () -> ()) {
+public func runRaceTest(
+  trials: Int, threads: Int? = nil, invoking body: () -> ()
+) {
   ClosureBasedRaceTest.thread = body
   runRaceTest(ClosureBasedRaceTest.self, trials: trials, threads: threads)
 }

stdlib/private/StdlibUnittest/StdlibCoreExtras.swift

@@ -214,7 +214,7 @@ extension MutableCollection
 }
 
 /// Generate all permutations.
-public func forAllPermutations(_ size: Int, body: ([Int]) -> Void) {
+public func forAllPermutations(_ size: Int, _ body: ([Int]) -> Void) {
   var data = Array(0..<size)
   repeat {
     body(data)
@@ -223,7 +223,7 @@ public func forAllPermutations(_ size: Int, body: ([Int]) -> Void) {
 
 /// Generate all permutations.
 public func forAllPermutations<S : Sequence>(
-  _ sequence: S, body: ([S.Iterator.Element]) -> Void
+  _ sequence: S, _ body: ([S.Iterator.Element]) -> Void
 ) {
   let data = Array(sequence)
   forAllPermutations(data.count) {

stdlib/private/StdlibUnittest/StdlibUnittest.swift.gyb

@@ -107,7 +107,7 @@ var _seenExpectCrash = false
 /// Run `body` and expect a failure to happen.
 ///
 /// The check passes iff `body` triggers one or more failures.
-public func expectFailure(${TRACE}, body: () -> Void) {
+public func expectFailure(${TRACE}, invoking body: () -> Void) {
   let startAnyExpectFailed = _anyExpectFailed
   _anyExpectFailed = false
   body()
@@ -2228,7 +2228,7 @@ public func expectEqualSequence<
 ) where
   Expected.Iterator.Element == Actual.Iterator.Element {
 
-  if !expected.elementsEqual(actual, isEquivalent: sameValue) {
+  if !expected.elementsEqual(actual, by: sameValue) {
     expectationFailure("expected elements: \"\(expected)\"\n"
       + "actual: \"\(actual)\" (of type \(String(reflecting: actual.dynamicType)))",
       trace: ${trace})
@@ -2246,9 +2246,9 @@ public func expectEqualsUnordered<
   Expected.Iterator.Element == Actual.Iterator.Element {
 
   let x: [Expected.Iterator.Element] =
-    expected.sorted(isOrderedBefore: compose(compare, { $0.isLT() }))
+    expected.sorted(by: compose(compare, { $0.isLT() }))
   let y: [Actual.Iterator.Element] =
-    actual.sorted(isOrderedBefore: compose(compare, { $0.isLT() }))
+    actual.sorted(by: compose(compare, { $0.isLT() }))
   expectEqualSequence(
     x, y, ${trace}, sameValue: compose(compare, { $0.isEQ() }))
 }
@@ -2345,10 +2345,10 @@ public func expectEqualsUnordered<
   }
 
   let x: [(T, T)] =
-    expected.sorted(isOrderedBefore: comparePairLess)
+    expected.sorted(by: comparePairLess)
   let y: [(T, T)] =
     actual.map { ($0.0, $0.1) }
-      .sorted(isOrderedBefore: comparePairLess)
+      .sorted(by: comparePairLess)
 
   func comparePairEquals(_ lhs: (T, T), rhs: (key: T, value: T)) -> Bool {
     return lhs.0 == rhs.0 && lhs.1 == rhs.1

stdlib/private/StdlibUnittest/TypeIndexed.swift

@@ -59,7 +59,7 @@ extension TypeIndexed where Value : Strideable {
     showFrame: Bool = true,
     stackTrace: SourceLocStack = SourceLocStack(),  
     file: String = #file, line: UInt = #line,
-    body: () -> R
+    invoking body: () -> R
   ) -> R {
     let expected = self[t].advanced(by: 1)
     let r = body()
@@ -77,7 +77,7 @@ extension TypeIndexed where Value : Equatable {
     showFrame: Bool = true,
     stackTrace: SourceLocStack = SourceLocStack(),  
     file: String = #file, line: UInt = #line,
-    body: () -> R
+    invoking body: () -> R
   ) -> R {
     let expected = self[t]
     let r = body()

stdlib/private/StdlibUnittestFoundationExtras/StdlibUnittestFoundationExtras.swift

@@ -65,7 +65,7 @@ public func withOverriddenLocaleCurrentLocale<Result>(
 /// return-autoreleased optimization.)
 @inline(never)
 public func autoreleasepoolIfUnoptimizedReturnAutoreleased(
-  _ body: @noescape () -> Void
+  invoking body: @noescape () -> Void
 ) {
 #if arch(i386) && (os(iOS) || os(watchOS))
   autoreleasepool(body)

stdlib/public/SDK/Foundation/NSStringAPI.swift

@@ -76,7 +76,8 @@ extension Optional {
   /// `body` is complicated than that results in unnecessarily repeated code.
   internal func _withNilOrAddress<NSType : AnyObject, ResultType>(
     of object: inout NSType?,
-    body: @noescape (AutoreleasingUnsafeMutablePointer<NSType?>?) -> ResultType
+    _ body:
+      @noescape (AutoreleasingUnsafeMutablePointer<NSType?>?) -> ResultType
   ) -> ResultType {
     return self == nil ? body(nil) : body(&object)
   }
@@ -495,7 +496,9 @@ extension String {
   //     enumerateLinesUsing:(void (^)(NSString *line, BOOL *stop))block
 
   /// Enumerates all the lines in a string.
-  public func enumerateLines(_ body: (line: String, stop: inout Bool) -> ()) {
+  public func enumerateLines(
+    invoking body: (line: String, stop: inout Bool) -> ()
+  ) {
     _ns.enumerateLines {
       (line: String, stop: UnsafeMutablePointer<ObjCBool>)
     in
@@ -526,7 +529,7 @@ extension String {
     scheme tagScheme: String,
     options opts: NSLinguisticTagger.Options = [],
     orthography: NSOrthography? = nil,
-    _ body:
+    invoking body:
       (String, Range<Index>, Range<Index>, inout Bool) -> ()
   ) {
     _ns.enumerateLinguisticTags(