[Issue 14786] The built-in exponentiation operator ^^ sometimes returns a value with the wrong sign.

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14786

--- Comment #2 from Iain Buclaw <ibuclaw at gdcproject.org> ---
This seems to be the correct extract from std.math to look at:

---
5675│             // Result is real only if y is an integer
5676│             // Check for a non-zero fractional part
5677├>            if (y > -1.0 / real.epsilon && y < 1.0 / real.epsilon)
5678│             {
5679│                 long w = cast(long)y;
5680│                 if (w != y)
5681│                     return sqrt(x); // Complex result -- create a NaN
5682│                 if (w & 1) sign = -1.0;
5683│             }
5684│             x = -x;
---


If 'e = long.max', it is representable, and the (w & 1) check sets sign to
'-1.0'

As instead 'e = long.max + 2', it is not representable, and so the signed-ness
is not adjusted.


Checked result against libm routines, and yes it looks like a bug on our side.

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