Trying to build 5.0.91 for Fedora rawhide with gcc 9.0.1 pre-release:
general/logspace.m
............................................./usr/include/c++/9/complex:696:
std::complex<_Tp> std::polar(const _Tp&, const _Tp&) [with _Tp =
double]: Assertion '__rho >= 0' failed.
BUILDSTDERR: fatal: caught signal Aborted -- stopping myself...
BUILDSTDERR: /bin/sh: line 1: 7442 Aborted (core
dumped) /bin/sh ../run-octave --norc --silent --no-history -p
/builddir/build/BUILD/octave-5.0.91
https://copr-be.cloud.fedoraproject.org/results/@scitech/octave5.1/fedora-rawhide-x86_64/00855554-octave/build.log.gz
Unfortunately I don't have direct access to a rawhide machine at the
moment to try to debug further.