NSNumber Bug I can't fix

[Marcus Müller]

Hi,

I just stumbled across a bug in NSNumber that I can't fix as I don't understand the NSNumber code. The problem is easy to see, though:

#import <Foundation/Foundation.h>

int main(int argc, char *argv[]) {

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

NSNumber *n   = [NSNumber numberWithInt:2];

NSNumber *nan = [NSDecimalNumber notANumber];

NSLog(@"%@ (class:%@ double:%g) == %@ -> %s",

  n, NSStringFromClass([n class]), [n doubleValue],

  nan, [n isEqualToNumber:nan] ? "YES" : "NO");

[pool release];

return 0;

}

On FreeBSD-8.2rc3 (amd64) this produces the following output:

2011-02-17 16:02:15.316 NumberTest[59574] 2 (class:NSIntNumber double:2) == NaN -> YES

Which is clearly wrong.

I came across this issue via NSNumberFormatter, which instead of formatting any integer numbers always printed NaN. In my project  I tried to debug into the issue and found this:

769  if ([anObject isEqual: [NSDecimalNumber notANumber]])

(gdb) s

-[NSNumber isEqual:] (self=0x803e8d1d0, _cmd=0x801410980, anObject=0x805e625c0)

    at NSNumber.m:376

376  if ([anObject isKindOfClass: NSNumberClass])

(gdb) n

378      return [self isEqualToNumber: anObject];

(gdb) po anObject

NaN

(gdb) po [anObject class]

NSDecimalNumber

(gdb) s

-[NSNumber isEqualToNumber:] (self=0x803e8d1d0, _cmd=0x80140d300, 

    aNumber=0x805e625c0) at NSNumber.m:371

371  return ([self compare: aNumber] == NSOrderedSame) ? YES : NO;

(gdb) s

-[NSSignedIntegerNumber compare:] (self=0x803e8d1d0, _cmd=0x80140d2e0, 

    aNumber=0x805e625c0) at NSNumber.m:107

107  if (aNumber == self)

[…]

(gdb) n

165  double value = [self doubleValue];

(gdb) p other

$3 = nan(0x8000000000000)

(gdb) p value

$4 = 6.9533556002420585e-310

As you can see above, asking an NSIntNumber instance for its doubleValue works properly, however, it fails at NSNumber.m:165. I don't know the reason, but I also don't understand the implications of the macros used. Can somebody elaborate? Please note that I'm on a 64-bit (amd64) system.

Thanks,

  Marcus

-- 

Marcus Mueller  .  .  .  crack-admin/coder ;-)

Mulle kybernetiK  .  http://www.mulle-kybernetik.com

Current projects: http://www.mulle-kybernetik.com/znek/

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