RE: [External] : Supplying DOC string in a `defun' using `defvar'

[Drew Adams]

> > (defun my-fun (x)
> >   (:documentation my-doc)
> >   (+ x 42))
> 
> Had noticed what happened, but (:documentation my-doc) is not taking effect
> and get "function not documented".

It works for me.  However, at least in Emacs 27.2,
`:documentation' is not documented in the Elisp manual,
except for use by `cl-generic'.  That seems like a bug.

(But `:doc' is documented, for use by `defcustom'.
And grepping shows that there is also `:doc-spec'.)