fix(cmdline): avoid 'incsearch' recursion after redraw #39303

Problem:  A vim.ui_attach() callback that redraws to show a 'verbose'
          regex message during 'incsearch' results in recusive redrawing.

Solution: Check that curwin was redrawn instead of just any window when
          determining if 'incsearch' highlighting was cleared.

src/nvim/buffer_defs.h

@@ -1294,6 +1294,7 @@ struct window_S {
   bool w_redr_status;               // if true statusline/winbar must be redrawn
   bool w_redr_border;               // if true border must be redrawn
   bool w_redr_statuscol;            // if true 'statuscolumn' must be redrawn
+  disptick_T w_display_tick;        // when window was last drawn.
 
   // remember what is shown in the 'statusline'-format elements
   pos_T w_stl_cursor;                // cursor position when last redrawn

src/nvim/drawscreen.c

@@ -2321,6 +2321,8 @@ redr_statuscol:
 
   wp->w_lines_valid = MAX(wp->w_lines_valid, idx);
 
+  wp->w_display_tick = display_tick;
+
   // Let the syntax stuff know we stop parsing here.
   if (syntax_last_parsed != 0 && syntax_present(wp)) {
     syntax_end_parsing(wp, syntax_last_parsed + 1);

src/nvim/ex_getln.c

@@ -1291,7 +1291,7 @@ static int command_line_execute(VimState *state, int key)
     return -1;  // get another key
   }
 
-  disptick_T display_tick_saved = display_tick;
+  disptick_T display_tick_saved = curwin->w_display_tick;
   CommandLineState *s = (CommandLineState *)state;
   s->c = key;
 
@@ -1322,7 +1322,7 @@ static int command_line_execute(VimState *state, int key)
       init_incsearch_state(&s->is_state);
     }
     // Re-apply 'incsearch' highlighting in case it was cleared.
-    if (display_tick > display_tick_saved && s->is_state.did_incsearch) {
+    if (curwin->w_display_tick > display_tick_saved && s->is_state.did_incsearch) {
       may_do_incsearch_highlighting(s->firstc, s->count, &s->is_state);
     }
     // If f_setcmdline() changed the cmdline treat it as such.

test/functional/ui/cmdline2_spec.lua

@@ -263,6 +263,18 @@ describe('cmdline2', function()
     ]])
     t.eq({ CmdlineChanged = 1, CursorMovedC = 1 }, exec_lua('return _G.events'))
   end)
+
+  it("no 'incsearch' recursion with 'verbose' regex message", function()
+    exec('set verbose=1')
+    feed([[:%s/.\{//}]])
+    screen:expect([[
+                                                           |
+      {1:~                                                    }|*9
+      {3:                                                     }|
+      Switching to backtracking RE engine for pattern: .\{ |*2
+      {16::}%{15:s}{16:/.\{//}^ }                                          |
+    ]])
+  end)
 end)
 
 describe('cmdline2', function()