Casting double to ulong weirdness

[via Digitalmars-d]

On Tuesday, 25 August 2015 at 14:54:41 UTC, Steven Schveighoffer 
wrote:
> On 8/25/15 9:51 AM, "=?UTF-8?B?Ik3DoXJjaW8=?= Martins\" 
> <marcioapm at gmail.com>\"" wrote:
>>      [...]
>
> Sorry, I misunderstood what epsilon was (I think it's the 
> smallest incremental value for a given floating point type with 
> an exponent of 1). Because your number is further away than 
> this value, it doesn't help.
>
> You need to add something to correct for the error that might 
> exist. The best thing to do is to add a very small number, as 
> that will only adjust truly close numbers.
>
> In this case, the number you could add is 0.1, since it's not 
> going to affect anything other than a slightly-off value. It 
> depends on where you expect the error to be.
>
> As bachmeier says, it's not something that's easy to get right.
>
>>      [...]
>
> these work because you have converted to double, which appears 
> to round up.
>
> -Steve

I didn't convert to double. My computations are all in double to 
start with, as you can see for my explicit types everywhere.

If you compile it with *GDC* it works fine. If you compile a port 
with clang, gcc or msvc, it works right as well. I suspect it 
will also work fine with LDC.