bug#50194: 28.0.50; tabulated-list-print (with non-nil UPDATE argument) doesn't clean up excess entries

[Shitikanth <shitikanth1@gmail.com>]

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Proposed fix.

On Wed, 25 Aug 2021 at 00:26, Shitikanth <shitikanth1@gmail.com> wrote:
>
> (tabulated-list-print nil t) does not seem to clean up excess remaining
> entries/lines if the number of tabulated-list-entries has decreased.
>
> Demo:
>     (defun demo-generate-entries (n)
>         (mapcar (lambda (i)
>                   (list i (vector (format "title %s" i))))
>                 (number-sequence 1 n)))
>
>     (let ((buf (get-buffer-create "*demo*")))
>       (with-current-buffer buf
>         (tabulated-list-mode)
>         (setq tabulated-list-format '[("title" 70 t)])
>         (setq tabulated-list-sort-key '("title"))
>         (setq tabulated-list-entries (demo-generate-entries 8))
>         (tabulated-list-print)
>         (pop-to-buffer buf)
>         (setq tabulated-list-entries (demo-generate-entries 4))
>         (tabulated-list-print nil t)
>         ))
>
> Expected behaviour:
> At the end, *demo* buffer should show only 4 entries.
>
> Observed behaviour:
> *demo* buffer still holds 8 entries, still showing 4 entries that are
> now removed from tabulated-list-entries.
>
>
>

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From 3a910de8512c125810f8681b1bcae41fa3135318 Mon Sep 17 00:00:00 2001
From: Shitikanth Kashyap <shitikanth1@gmail.com>
Date: Wed, 25 Aug 2021 00:33:55 +0530
Subject: [PATCH] tabulated-list-print delete excess lines (bug#50194)

---
 lisp/emacs-lisp/tabulated-list.el | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lisp/emacs-lisp/tabulated-list.el b/lisp/emacs-lisp/tabulated-list.el
index f0ee78745a..fecfa91147 100644
--- a/lisp/emacs-lisp/tabulated-list.el
+++ b/lisp/emacs-lisp/tabulated-list.el
@@ -481,6 +481,8 @@ tabulated-list-print
               (forward-line 1)
               (delete-region old (point))))))
       (setq entries (cdr entries)))
+    (when update
+      (delete-region (point) (point-max)))
     (set-buffer-modified-p nil)
     ;; If REMEMBER-POS was specified, move to the "old" location.
     (if saved-pt
-- 
2.25.1