Don't call undefined function elisp-eldoc-documentation-function (bug#42493)

* lisp/ielm.el (inferior-emacs-lisp-mode): Add
`elisp-eldoc-var-docstring' and `elisp-eldoc-funcall' as
`eldoc-documentation-functions' instead of the undefined
elisp-eldoc-documentation-function (bug#42493).

1 files changed, 3 insertions, 1 deletions

diff --git a/lisp/ielm.el b/lisp/ielm.el
index 47c5158ce41..b3654b91d37 100644
--- a/lisp/ielm.el
+++ b/lisp/ielm.el
@@ -537,7 +537,9 @@ Customized bindings may be defined in `ielm-map', which currently contains:
        '(comint-replace-by-expanded-history
          ielm-complete-filename elisp-completion-at-point))
   (add-hook 'eldoc-documentation-functions
-            #'elisp-eldoc-documentation-function nil t)
+            #'elisp-eldoc-var-docstring nil t)
+  (add-hook 'eldoc-documentation-functions
+            #'elisp-eldoc-funcall nil t)
   (set (make-local-variable 'ielm-prompt-internal) ielm-prompt)
   (set (make-local-variable 'comint-prompt-read-only) ielm-prompt-read-only)
   (setq comint-get-old-input 'ielm-get-old-input)