[Issue 15720] iota(long.max, long.min, step) does not work properly

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15720

Ender KaShae <astrothayne at gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |astrothayne at gmail.com

--- Comment #1 from Ender KaShae <astrothayne at gmail.com> ---
This happens because the operation to compute the length is

```
unsigned((start - stop) / -step)
```

but `long.max - long.min` overflows the long and results in -1. 

The reason it works for a step of 1 is that -1 is cast to a ulong, which
results in the maximum value of ulong (18446744073709551615). 

Maybe this could be fixed by casting to the unsigned type before dividing by
the step.

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