Revert "SR-1464: NSNumber.description is not compatible between OS X and linux"

This reverts commit d99a2f6.

See discussion in #1929 for details.

Author: weissi

CoreFoundation/String.subproj/CFString.c

@@ -5996,7 +5996,7 @@ enum {
     CFFormatDummyPointerType = 42	/* special case for %n */
 };
 
-#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_WINDOWS || DEPLOYMENT_TARGET_LINUX
+#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_WINDOWS
 /* Only come in here if spec->type is CFFormatLongType or CFFormatDoubleType. Pass in 0 for width or precision if not specified. Returns false if couldn't do the format (with the assumption the caller falls back to unlocalized).
 */
 static Boolean __CFStringFormatLocalizedNumber(CFMutableStringRef output, CFLocaleRef locale, const CFPrintValue *values, const CFFormatSpec *spec, SInt32 width, SInt32 precision, Boolean hasPrecision) {
@@ -6980,7 +6980,7 @@ static void __CFStringAppendFormatCore(CFMutableStringRef outputString, CFString
 	switch (specs[curSpec].type) {
 	case CFFormatLongType:
 	case CFFormatDoubleType:
-#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_WINDOWS || DEPLOYMENT_TARGET_LINUX
+#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_WINDOWS
             if (localizedFormatting && (specs[curSpec].flags & kCFStringFormatLocalizable)) {    // We have a locale, so we do localized formatting
                 if (__CFStringFormatLocalizedNumber(outputString, (CFLocaleRef)formatOptions, values, &specs[curSpec], width, precision, hasPrecision)) break;
             }

Foundation/NSNumber.swift

@@ -915,7 +915,7 @@ open class NSNumber : NSValue {
     }
 
     open var stringValue: String {
-        return self.description
+        return description(withLocale: nil)
     }
 
     /// Create an instance initialized to `value`.
@@ -958,86 +958,39 @@ open class NSNumber : NSValue {
         }
     }
 
-    open func description(withLocale locale: Locale?) -> String {
-        guard let locale = locale else { return self.description }
-        switch _CFNumberGetType2(_cfObject) {
-        case kCFNumberSInt8Type, kCFNumberCharType:
-            return String(format: "%d", locale: locale, self.int8Value)
-
-        case kCFNumberSInt16Type, kCFNumberShortType:
-            return String(format: "%hi", locale: locale, self.int16Value)
-
-        case kCFNumberSInt32Type:
-            return String(format: "%d", locale: locale, self.int32Value)
+    private static let _numberFormatterForNilLocale: CFNumberFormatter = {
+        let formatter: CFNumberFormatter
+        formatter = CFNumberFormatterCreate(nil, CFLocaleCopyCurrent(), kCFNumberFormatterNoStyle)
+        CFNumberFormatterSetProperty(formatter, kCFNumberFormatterMaxFractionDigits, 15._bridgeToObjectiveC())
+        return formatter
+    }()
 
-        case kCFNumberIntType, kCFNumberLongType, kCFNumberNSIntegerType, kCFNumberCFIndexType:
-            return String(format: "%ld", locale: locale, self.intValue)
-
-        case kCFNumberSInt64Type, kCFNumberLongLongType:
-            return String(format: "%lld", locale: locale, self.int64Value)
-
-        case kCFNumberSInt128Type:
-            let value = self.int128Value
-            if value.high == 0 {
-                return value.low.description    // BUG: "%llu" doesnt work correctly and treats number as signed
-            } else {
-                // BUG: Note the locale is actually ignored here as this is converted using CFNumber.c:emit128()
-                return String(format: "%@", locale: locale, unsafeBitCast(_cfObject, to: UnsafePointer<CFNumber>.self))
-            }
-
-        case kCFNumberFloatType, kCFNumberFloat32Type:
-            return String(format: "%0.7g", locale: locale, self.floatValue)
-
-        case kCFNumberFloat64Type, kCFNumberDoubleType:
-            return String(format: "%0.16g", locale: locale, self.doubleValue)
+    open func description(withLocale locale: Locale?) -> String {
+        // CFNumberFormatterCreateStringWithNumber() does not like numbers of type
+        // SInt128Type, as it loses the type when looking it up and treats it as
+        // an SInt64Type, so special case them.
+        if _CFNumberGetType2(_cfObject) == kCFNumberSInt128Type {
+            return String(format: "%@", unsafeBitCast(_cfObject, to: UnsafePointer<CFNumber>.self))
+        }
 
-        case kCFNumberCGFloatType:
-            if Int.max == Int32.max {
-                return String(format: "%0.7g", locale: locale, self.floatValue)
-            } else {
-                return String(format: "%0.16g", locale: locale, self.doubleValue)
-            }
-        default: fatalError("Unknown NSNumber Type")
+        let aLocale = locale
+        let formatter: CFNumberFormatter
+        if (aLocale == nil) {
+            formatter = NSNumber._numberFormatterForNilLocale
+        } else {
+            formatter = CFNumberFormatterCreate(nil, aLocale?._cfObject, kCFNumberFormatterDecimalStyle)
         }
+        return CFNumberFormatterCreateStringWithNumber(nil, formatter, self._cfObject)._swiftObject
     }
 
     override open var _cfTypeID: CFTypeID {
         return CFNumberGetTypeID()
     }
 
     open override var description: String {
-        switch _CFNumberGetType2(_cfObject) {
-        case kCFNumberSInt8Type, kCFNumberCharType, kCFNumberSInt16Type, kCFNumberShortType,
-             kCFNumberSInt32Type, kCFNumberIntType, kCFNumberLongType, kCFNumberNSIntegerType, kCFNumberCFIndexType:
-            return self.intValue.description
-
-        case kCFNumberSInt64Type, kCFNumberLongLongType:
-            return self.int64Value.description
-
-        case kCFNumberSInt128Type:
-            let value = self.int128Value
-            if value.high == 0 {
-                return value.low.description
-            } else {
-                return String(format: "%@", locale: nil, unsafeBitCast(_cfObject, to: UnsafePointer<CFNumber>.self))
-            }
-
-        case kCFNumberFloatType, kCFNumberFloat32Type:
-            return self.floatValue.description
-
-        case kCFNumberFloat64Type, kCFNumberDoubleType:
-            return self.doubleValue.description
-
-        case kCFNumberCGFloatType:
-            if Int.max == Int32.max {
-                return self.floatValue.description
-            } else {
-                return self.doubleValue.description
-            }
-        default: fatalError("Unknown NSNumber Type")
-        }
+        return description(withLocale: nil)
     }
-
+    
     internal func _cfNumberType() -> CFNumberType {
         switch objCType.pointee {
         case 0x42: return kCFNumberCharType