>
> The command "C-u C-h d regexp RET" brings up 111 matching functions.
> Who will have patience looking through that list, unless the likely
> candidates are near the beginning?  And this is even before we added
> aliases that use the regexp- prefix.


If the goal is to list all the functions related to manipulating the topic
of regexp (something like
https://docs.python.org/2/library/re.html#regular-expression-objects or
https://ruby-doc.org/core-2.7.1/Regexp.html), then the search you propose
is a poor tool.

It starts with the following list: grep-regexp-alist, gmm-regexp-concat,
project-find-regexp, shell-dumb-shell-regexp, rmail-secondary-file-regexp,
rmail-user-mail-address-regexp, tramp-file-name-regexp,
whitespace-indentation-regexp, project-or-external-find-regexp... All of
which are irrelevant to what we search.

What it should list is
https://www.gnu.org/software/emacs/manual/html_node/elisp/Regexp-Search.html,
but also merged with the Match Data documentation, presented in a much more
condensed manner, etc.

Philippe