stdlib: make the non-native Array.count smaller more efficient.

eeckstein · eeckstein · commit 87298c07c837 · 2019-11-26T18:20:39.000+01:00
Use _CocoaArrayWrapper.endIndex which returns the NSArray.count.
In the old version, "count" translated to RandomAccessCollection.count, which ended up in multiple calls to endIndex.
diff --git a/stdlib/public/core/ArrayBuffer.swift b/stdlib/public/core/ArrayBuffer.swift
@@ -266,7 +266,7 @@ extension _ArrayBuffer {
   internal var count: Int {
     @inline(__always)
     get {
-      return _fastPath(_isNative) ? _native.count : _nonNative.count
+      return _fastPath(_isNative) ? _native.count : _nonNative.endIndex
     }
     set {
       _internalInvariant(_isNative, "attempting to update count of Cocoa array")

Original file line number	Diff line number	Diff line change
`@@ -266,7 +266,7 @@ extension _ArrayBuffer {`
`266`	`266`	`internal var count: Int {`
`267`	`267`	`@inline(__always)`
`268`	`268`	`get {`
`269`		`- return _fastPath(_isNative) ? _native.count : _nonNative.count`
	`269`	`+ return _fastPath(_isNative) ? _native.count : _nonNative.endIndex`
`270`	`270`	`}`
`271`	`271`	`set {`
`272`	`272`	`_internalInvariant(_isNative, "attempting to update count of Cocoa array")`