Add argument error for int.parse(null).

runtime/lib/integers_patch.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Dart core library.
 
 // VM implementation of int.
 
 patch class int {
 
   static bool is64Bit() => 1 << 32 is _Smi;
 
   static int _tryParseSmi(String str, int first, int last) {
     assert(first <= last);
     var ix = first;
     var sign = 1;
     var c = str.codeUnitAt(ix);
     // Check for leading '+' or '-'.
     if ((c == 0x2b) || (c == 0x2d)) {
       ix++;
       sign = 0x2c - c;  // -1 for '-', +1 for '+'.
       if (ix > last) {
         return null;  // Empty.
       }
     }
-    int smiLimit = is64Bit() ? 18 : 9;
+    var smiLimit = is64Bit() ? 18 : 9;
     if ((last - ix) >= smiLimit) {
       return null;  // May not fit into a Smi.
     }
     var result = 0;
     for (int i = ix; i <= last; i++) {
-      var c = str.codeUnitAt(i) - 0x30;
-      if ((c > 9) || (c < 0)) {
+      var c = 0x30 ^ str.codeUnitAt(i);
+      if (9 < c) {
         return null;
       }
-      result = result * 10 + c;
+      result = 10 * result + c;
     }
     return sign * result;
   }
 
   static int _tryParseSmiWhitespace(String str) {
     int first = str._firstNonWhitespace();
     if (first < str.length) {
       int last = str._lastNonWhitespace();
       int res = _tryParseSmi(str, first, last);
       if (res != null) return res;
     }
     return _native_parse(str);
   }
 
   static int _parse(String str) {
     int res = _tryParseSmi(str, 0, str.length - 1);
     if (res != null) return res;
     return _tryParseSmiWhitespace(str);
   }
 
   static int _native_parse(String str) native "Integer_parse";
 
   static int _throwFormatException(String source, int position) {
     throw new FormatException("", source, position);
   }
 
   /* patch */ static int parse(String source,
                                { int radix,
                                  int onError(String str) }) {
+    if (identical(source, null)) throw new ArgumentError(source);

[srdjan, 2014/09/17 15:13:53]

Please explain why you are using identical instead of ==.

[Lasse Reichstein Nielsen, 2014/09/17 15:28:04]

Ack, a silly attempt to see if it made any difference (it didn't), but I forgot
to roll it back.
I'll undo that.

     if (radix == null) {
       int result;
       if (source.isNotEmpty) result = _parse(source);
       if (result == null) {
         if (onError == null) {
           throw new FormatException("", source);
         }
         return onError(source);
       }
       return result;
@@ skipping 46 matching lines @@
       int digit = digits[code - 0x30];
       if (digit >= radix) return onError(source);
       result = result * radix + digit;
       i++;
       if (i == end) break;
       code = source.codeUnitAt(i);
     } while (true);
     return negative ? -result : result;
   }
 }