BUILD FAILED (macOS 15.6.1 on arm64 using ruby-build 20251008)

[TristinL]

Hiyah! I'm new to rbenv and I can't seem to install any version of ruby on my machine.
rbenv error log.txt

I see one error in the log:
readline.c:1903:37: error: use of undeclared identifier 'username_completion_function'; did you mean 'rl_username_completion_function'?
1903 | rl_username_completion_function);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| rl_username_completion_function
readline.c:79:42: note: expanded from macro 'rl_username_completion_function'
79 | # define rl_username_completion_function username_completion_function
| ^
/usr/local/opt/readline/include/readline/readline.h:496:14: note: 'rl_username_completion_function' declared here
496 | extern char *rl_username_completion_function (const char *, int);
| ^
1 error generated.

I truthfully am out of my depth here and have no idea what is causing this error. Any ideas would be greatly appreciated. I'm worried googling would lead me down a more broken path than just asking the experts.

[TristinL]

Okay it seems the issue was my install of homebrew.
Had to follow the info HERE to uninstall homebrew and reinstall it.
Note for any others to make sure your mac M3 chip isn't to blame/your homebrew isn't installed improperly