fix: setting tabline option not redrawing tabline

With #20374 tabline option is marked with 'statuslines' redraw flag.
But 'statuslines' doesn't redraw tabline. As a result, tabline doesn't
get redrawn when tabline option is set and statuslines get unnecessarily redrawn.

This patch fixes the issue by adding a new redraw flag P_RTABL to redraw
tabline.

4 files changed, 8 insertions, 2 deletions

diff --git a/src/nvim/generators/gen_options.lua b/src/nvim/generators/gen_options.lua
index 6dba6552b3..4e4dd83367 100644
--- a/src/nvim/generators/gen_options.lua
+++ b/src/nvim/generators/gen_options.lua
@@ -30,6 +30,7 @@ local type_flags={
 
 local redraw_flags={
   statuslines='P_RSTAT',
+  tabline = 'P_RTABL',
   current_window='P_RWIN',
   current_window_only='P_RWINONLY',
   current_buffer='P_RBUF',
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 1a6cd0c1af..06662afd08 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -2648,6 +2648,10 @@ void check_redraw(uint32_t flags)
     status_redraw_all();
   }
 
+  if ((flags & P_RTABL) || all) {  // mark tablines dirty
+    redraw_tabline = true;
+  }
+
   if ((flags & P_RBUF) || (flags & P_RWIN) || all) {
     changed_window_setting();
   }
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index c4333a6f61..19e4780e0a 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -24,6 +24,7 @@
 #define P_NO_MKRC      0x200U       ///< don't include in :mkvimrc output
 
 // when option changed, what to display:
+#define P_RTABL        0x800U       ///< redraw tabline
 #define P_RSTAT        0x1000U      ///< redraw status lines
 #define P_RWIN         0x2000U      ///< redraw current window and recompute text
 #define P_RBUF         0x4000U      ///< redraw current buffer and recompute text
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index 8a883a09c3..ba483d3714 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -19,7 +19,7 @@
 -- types: bool, number, string
 -- lists: (nil), comma, onecomma, flags, flagscomma
 -- scopes: global, buffer, window
--- redraw options: statuslines, current_window, curent_window_only,
+-- redraw options: statuslines, tabline, current_window, curent_window_only,
 --                 current_buffer, all_windows, curswant
 -- defaults: {condition=#if condition, if_true=default, if_false=default}
 -- #if condition:
@@ -2407,7 +2407,7 @@ return {
       short_desc=N_("custom format for the console tab pages line"),
       type='string', scope={'global'},
       modelineexpr=true,
-      redraw={'statuslines'},
+      redraw={'tabline'},
       varname='p_tal',
       defaults={if_true=""}
     },