This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
hexfp: signbit() works on NVs (nv), not on long doubles (fv).
The nv value should be a valid version of the fv value.
Why the fv is a long double, not a NV, is a long (haha) story.
Short version: the printf code expects to be able to work with long
doubles, if long doubles are available, even without -Duselongdouble.
The problem became obvious in VMS which has true 128-bit long
(little-endian) doubles, and trying the signbit() on those did
not work.
https://perl5.git.perl.org / perl5.git / commit