Fix NSString.boolValue not matching Darwin Foundation

Author: otaviolima

Foundation/NSString.swift

@@ -633,12 +633,16 @@ extension NSString {
         let scanner = Scanner(string: _swiftObject)
         // skip initial whitespace if present
         let _ = scanner.scanCharactersFromSet(.whitespaces)
-        // scan a single optional '+' or '-' character, followed by zeroes
-        if scanner.scanString("+") == nil {
-            let _ = scanner.scanString("-")
-        }
+        // scan a single optional '+' or '-' character
+        let hasSignal = scanner.scanString("+") != nil || scanner.scanString("-") != nil
         // scan any following zeroes
-        let _ = scanner.scanCharactersFromSet(CharacterSet(charactersIn: "0"))
+        let hasZeros = scanner.scanCharactersFromSet(CharacterSet(charactersIn: "0")) != nil
+
+        // If has leading signal or zeros then scan only numbers
+        if hasSignal || hasZeros {
+            return scanner.scanCharactersFromSet(CharacterSet(charactersIn: "123456789")) != nil
+        }
+
         return scanner.scanCharactersFromSet(CharacterSet(charactersIn: "tTyY123456789")) != nil
     }
 

TestFoundation/TestNSString.swift

@@ -99,7 +99,7 @@ class TestNSString: LoopbackServerTest {
         for string in trueStrings {
             XCTAssert(string.boolValue)
         }
-        let falseStrings: [NSString] = ["false", "FALSE", "fAlSe", "no", "NO", "0", "<true>", "_true", "-00000"]
+        let falseStrings: [NSString] = ["false", "FALSE", "fAlSe", "no", "NO", "0", "<true>", "_true", "-00000", "+t", "+", "0t", "++"]
         for string in falseStrings {
             XCTAssertFalse(string.boolValue)
         }