On Wednesday, 6 December 2023 at 12:38:35 UTC, Nick Treleaven
wrote:
Correct. So I expected a NaN output for x. However, I wasn't
expecting lo == 13835058055282163712 and hi == 32767 where x
is of type real, or lo == 9221120237041090560 and hi = 0 where
x is of type double. Based on the default initialization
rules, I expected both lo and hi to have a value of zero
regardless if x is of type double or real. This is what I'm
trying to understand, how are these values derived?
ulong.sizeof is 8, like double.sizeof. So F.init.lo should have
the same bit pattern as F.init.x because they share storage
exactly. F.init.hi should be 0 and it is on my system. (*"If
the union is larger than the first field, the remaining bits
are set to 0"*). I don't know why you don't get zero for that.
Oops, you said you did get zero in that case, so all is well.
When `x` is `real`, that may overlap with `F.hi` because `real`
can be more than 8 bytes.
