Bison HEAD failure on RHEL 7.7

[Paul Eggert]

On RHEL 7.7 when I attempt to build Bison HEAD (commit 58302c6079f380c47237843dff3793de16e53419) on RHEL 7.7, I get several failures complaining "error: new declaration 'bool isnan(double)". I presume this is some Gnulib C++ thing, which is outside of my wheelhouse. I'm attaching one error directory to give more details.

bison-262-failure.tgz
Description: application/compressed-tar