hash.h: warnings produced with -Wfloat-equal

[digimokan]

In hash.h, when compiling with -Wfloat-equal, the "v == -0.0f" on line 401 (and similar on lines 435 and 469) produce "warning: comparing floating-point with '==' or '!=' is unsafe."

Using fpclassify and FP_ZERO to fix this issue would work, but I think these are not portable. It looks like signbit is portable (assuming you can use math.h or cmath?), so maybe something with signbit and '>' or '<' comparisons would work?

if (!(v < 0) && !(v > 0) && signbit(v))

[jwellbelove]

The issue is that fpclassify & signbit are not available for C++98 or C++03, which the ETL still maintains compatibility with. I may have to disable the warning for those lines or use !(v < 0) && !(v > 0).

[digimokan]

Ok, I didn't realize that. I'm not sure how to replace signbit portably.

[jwellbelove]

I think the test !(v < 0) && !(v > 0) should be enough, as the effective check is "For any variant of zero, make it positive zero".

[jwellbelove]

Fixed 20.38.7