I think autotools build is safe as it does the readline availability test with the very rl_completion_suppress_append symbol that is causing the problem here -> it won't consider libedit as readline.
There might be space for improvement in the autotools side in the documentation (some people may miss readline support as getting it enabled with homebrew can be a bit more involved than running ./configure with default parameters) and in our own CI build (that might lack readline support at the moment)
On a homebrew/macOS meson build (but might be relevant to autotools, in principle) where I think I don't have readline installed (unless it gets automatically installed as dependency of something else)
../server/stdinhand.c:7546:9: error: use of undeclared identifier 'rl_completion_suppress_append'
rl_completion_suppress_append = (setting_type(pset) == SST_BITWISE);
Homebrew readline documentation tells:
This formula is keg-only. Mac OS X provides similar software, and installing this software in parallel can cause all kinds of trouble.
OS X provides the BSD libedit library, which shadows libreadline. In order to prevent conflicts when programs look for libreadline we are defaulting this GNU Readline installation to keg-only.
So maybe I've got that libedit detected as a readline so the relevant functionality gets enabled. Yet the build fails against libedit.