Variable below zero but if statement doesn't grab?

[rumbu via Digitalmars-d-learn]

On Sunday, 27 December 2015 at 23:24:55 UTC, TheDGuy wrote:
> On Sunday, 27 December 2015 at 22:51:27 UTC, Ali Çehreli wrote:
>> On 12/27/2015 07:53 AM, TheDGuy wrote:
>>> Any idea what i am doing wrong?
>>> https://www.youtube.com/watch?v=j_VCa-5VeP8
>>
>> YouTube says that the video has been removed by the user. 
>> That's exactly the reason why I don't like even dpaste. There 
>> is no guarantee that such threads will be useful forever. :) 
>> For me, sample code should be right here, and it should be 
>> short enough to practically be here.
>>
>> Ali
>
> I deleted the video because the problem was solved, it was 
> neither a problem with the single '&' nor with my code it just 
> showed a strange behaviour while debugging but the function 
> returned the right value. Sample code is in my second post.

Get used to it :) Unfortunately, DMD is not emitting the best 
debug information. The program flow is correct, but the line info 
is not, that's why the execution step will not be triggered in 
the real location of the source code.

The simplest example is this:

import std.stdio;

void foo(int x)
{
     if (x > 0)              //step 1, correct
     {
         writeln("bigger");  //step 2, correct
     }
     else
     {
         writeln("lower");   //step 3, wrong
     }
}

int main(string[] argv)
{
     foo(20);   //breakpoint with step in
     return 0;
}

If you really want to confuse the debugger, write some asserts or 
contracts here and there and your program will be impossible to 
debug :)