`narrow-to-defun' fixup

* emacs-lisp/lisp.el (narrow-to-defun): `beginning-of-defun' goes
to previous function when point is on the first character of a
function. Take care of that in `narrow-to-defun'.

Fixes: debbugs:6157

1 files changed, 15 insertions, 1 deletions

diff --git a/lisp/emacs-lisp/lisp.el b/lisp/emacs-lisp/lisp.el
index 4efdc3240cd..bcb7fab026b 100644
--- a/lisp/emacs-lisp/lisp.el
+++ b/lisp/emacs-lisp/lisp.el
@@ -447,7 +447,21 @@ Optional ARG is ignored."
       ;; Try first in this order for the sake of languages with nested
       ;; functions where several can end at the same place as with
       ;; the offside rule, e.g. Python.
-      (beginning-of-defun)
+
+      ;; Finding the start of the function is a bit problematic since
+      ;; `beginning-of-defun' when we are on the first character of
+      ;; the function might go to the previous function.
+      ;;
+      ;; Therefore we first move one character forward and then call
+      ;; `beginning-of-defun'.  However now we must check that we did
+      ;; not move into the next function.
+      (let ((here (point)))
+        (unless (eolp)
+	  (forward-char))
+        (beginning-of-defun)
+        (when (< (point) here)
+          (goto-char here)
+          (beginning-of-defun)))
       (setq beg (point))
       (end-of-defun)
       (setq end (point))