On Saturday, 8 August 2020 at 22:13:57 UTC, Bruce Carneal wrote:
Per the original post in this thread, the current compiler
doesn't convert decimal floating point literals to binary form
correctly in all normal cases. Assuming people actually want
to be correct/consistent to the last bit wherever possible,
that should change.
Additionally, the default library conversions should match
those of the compiler. They should also be correct/consistent.
This could be accomplished by introducing Mir dependencies in a
few places but I think fully accredited copying is a better way
to go. There is more to maintain, true, but accurate
conversion is fundamental in nature. We're not talking about
some high level library here. Hard to get right? Apparently.
Esoteric? No.
As to timing, if the subnormal update Ilya mentioned is very
close it would make sense to wait for that version.
Side note: the truly persnickety/paranoid might favor hex
floating point literals but those are pretty hard on human
readers. At least the conversion implementations should not
require heroics.
OTOH, this is pretty small potatoes when compared to other CTFE
floating point discrepancies (no control of precision, all to
'real' IIUC). Maybe the best that can be done is to align the
library with better practice.
