Confusing LLDB output

Question

There's probably a hole in my C knowledge here, but I'm a little confused as to why this happening.

(lldb) p lineGroup
(NSInteger) $17 = -1
(lldb) p (lineGroup > 4)
(bool) $18 = true
(lldb) p (lineGroup < 0 )
(bool) $19 = false
(lldb) p (-1 < 0)
(bool) $20 = true
(lldb) p ((int)lineGroup < 0 )
(bool) $21 = false
(lldb) p ((int)lineGroup > 4)
(bool) $22 = true
(lldb) 

The lineGroup variable is assigned as follows:

- (void)gotLineGroupInformation:(NSString *)lineGroupString
{
    NSInteger lineGroup = [lineGroupString integerValue];
    if(lineGroup >= 0)
    {
        // Always gets called
    }
    else
    {
        // Never gets called
    }
}

Thanks, Andy

Answer 1

The lldb issue seem to be the exact same as in Objective C integer comparison error :

Carl Norum said in his response :

Confirmed - it's a bug in the lldb IR interpreter.

Here's a link to the patch that fixes it: http://lists.cs.uiuc.edu/pipermail/lldb-commits/Week-of-Mon-20130520/008569.html

---

Concerning your code, I tried to reproduce the bug without succes with this test:

NSString *lineGroupString = @"-1";
NSInteger lineGroup = [lineGroupString integerValue];
if(lineGroup >= 0)
{
    NSLog(@"positive");
}
else
{
    NSLog(@"negative"); // This log is correctly called every time
}

Maybe you should try to debug with NSLog for this one (in particular what is the value of lineGroupString right after entering the function ?).