From 5db4ec20fe4b428e15aa53208c9a9bfb037c0f30 Mon Sep 17 00:00:00 2001
From: Eli Zaretskii <eliz@gnu.org>
Date: Sun, 17 Jul 2022 12:33:34 +0300
Subject: [PATCH] Fix tab-bar resizing under 'auto-resize-tab-bars' =
 'grow-only'

* src/xdisp.c (redisplay_tab_bar): Compute the desired height of
the tab-bar before iterating over the tab-bar string, to detect
the required resizing earlier.  Default 'change_p' to 'false'.

* lisp/tab-bar.el (tab-bar--update-tab-bar-lines): Support
'auto-resize-tab-bars' set to 'grow-only'.
---
 lisp/tab-bar.el |  4 +++-
 src/xdisp.c     | 50 +++++++++++++++++++++++++++++--------------------
 2 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/lisp/tab-bar.el b/lisp/tab-bar.el
index c769dbabce4..1a3f35891ef 100644
--- a/lisp/tab-bar.el
+++ b/lisp/tab-bar.el
@@ -200,7 +200,9 @@ a list of frames to update."
                          (t frames))))
     ;; Loop over all frames and update `tab-bar-lines'
     (dolist (frame frame-lst)
-      (unless (frame-parameter frame 'tab-bar-lines-keep-state)
+      (unless (or (frame-parameter frame 'tab-bar-lines-keep-state)
+                  (and (eq auto-resize-tab-bars 'grow-only)
+                       (> (frame-parameter frame 'tab-bar-lines) 1)))
         (set-frame-parameter frame 'tab-bar-lines
                              (tab-bar--tab-bar-lines-for-frame frame)))))
   ;; Update `default-frame-alist'
diff --git a/src/xdisp.c b/src/xdisp.c
index 842277039d4..c0ef15f218c 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -14054,15 +14054,41 @@ redisplay_tab_bar (struct frame *f)
       return false;
     }
 
+  /* Build a string that represents the contents of the tab-bar.  */
+  build_desired_tab_bar_string (f);
+
+  int new_nrows;
+  int new_height = tab_bar_height (f, &new_nrows, true);
+
+  if (f->n_tab_bar_rows == 0)
+    {
+      f->n_tab_bar_rows = new_nrows;
+      if (new_height != WINDOW_PIXEL_HEIGHT (w))
+	frame_default_tab_bar_height = new_height;
+    }
+
+  /* If new_height or new_nrows indicate that we need to enlarge the
+     tab-bar window, we can return right away.  */
+  if (new_nrows > f->n_tab_bar_rows
+      || (EQ (Vauto_resize_tab_bars, Qgrow_only)
+	  && !f->minimize_tab_bar_window_p
+	  && new_height > WINDOW_PIXEL_HEIGHT (w)))
+    {
+      if (FRAME_TERMINAL (f)->change_tab_bar_height_hook)
+	FRAME_TERMINAL (f)->change_tab_bar_height_hook (f, new_height);
+      if (new_nrows != f->n_tab_bar_rows)
+	f->n_tab_bar_rows = new_nrows;
+      clear_glyph_matrix (w->desired_matrix);
+      f->fonts_changed = true;
+      return true;
+    }
+
   /* Set up an iterator for the tab-bar window.  */
   init_iterator (&it, w, -1, -1, w->desired_matrix->rows, TAB_BAR_FACE_ID);
   it.first_visible_x = 0;
   it.last_visible_x = WINDOW_PIXEL_WIDTH (w);
   row = it.glyph_row;
   row->reversed_p = false;
-
-  /* Build a string that represents the contents of the tab-bar.  */
-  build_desired_tab_bar_string (f);
   reseat_to_string (&it, NULL, f->desired_tab_bar_string, 0, 0, 0,
                     STRING_MULTIBYTE (f->desired_tab_bar_string));
   /* FIXME: This should be controlled by a user option.  But it
@@ -14074,22 +14100,6 @@ redisplay_tab_bar (struct frame *f)
      do.  */
   it.paragraph_embedding = L2R;
 
-  if (f->n_tab_bar_rows == 0)
-    {
-      int new_height = tab_bar_height (f, &f->n_tab_bar_rows, true);
-
-      if (new_height != WINDOW_PIXEL_HEIGHT (w))
-	{
-          if (FRAME_TERMINAL (f)->change_tab_bar_height_hook)
-            FRAME_TERMINAL (f)->change_tab_bar_height_hook (f, new_height);
-	  frame_default_tab_bar_height = new_height;
-	  /* Always do that now.  */
-	  clear_glyph_matrix (w->desired_matrix);
-	  f->fonts_changed = true;
-	  return true;
-	}
-    }
-
   /* Display as many lines as needed to display all tab-bar items.  */
 
   if (f->n_tab_bar_rows > 0)
@@ -14135,7 +14145,7 @@ redisplay_tab_bar (struct frame *f)
 
   if (!NILP (Vauto_resize_tab_bars))
     {
-      bool change_height_p = true;
+      bool change_height_p = false;
 
       /* If we couldn't display everything, change the tab-bar's
 	 height if there is room for more.  */
-- 
2.39.5