Thank you for the kind response. I understand what I was doing wrong now.

On Tue, Jun 6, 2023 at 2:31 AM Mattias Engdegård <
mattias.engdegard@gmail.com> wrote:

> The problem is that re-builder's handling of rx is badly designed, and you
> are not the first to be annoyed by this. In 'rx' mode, re-builder expects
> you to write a Lisp expression that can be used as argument to
> `rx-to-string`, something that nobody wants to do. In your case, instead of
>
>   (rx (or "a" "b") "c")
>
> you would have to write something like
>
>   '(seq (or "a" "b") "c")
>
> Note the quote (because the expression is evaluated) and `seq` (because
> `rx-to-string` only takes a single rx expression as input; `rx` forms an
> implicit `seq` of its arguments).
>
> Previous bugs:
>
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=60196
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=54107
>
>