vim-patch:9.0.0245: mechanism to prevent recursive screen updating is incomplete (#27448)

Problem:    Mechanism to prevent recursive screen updating is incomplete.
Solution:   Add "redraw_not_allowed" and set it in build_stl_str_hl().
            (issue vim/vim#10952)

https://github.com/vim/vim/commit/471c0fa3eed4f6207d1cb7636970547bfd2eee26

Co-authored-by: Bram Moolenaar <Bram@vim.org>

7 files changed, 33 insertions, 31 deletions

diff --git a/src/nvim/change.c b/src/nvim/change.c
index 2db3d007d7..a7c885bf4d 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -322,7 +322,7 @@ static void changed_common(buf_T *buf, linenr_T lnum, colnr_T col, linenr_T lnum
   FOR_ALL_TAB_WINDOWS(tp, wp) {
     if (wp->w_buffer == buf) {
       // Mark this window to be redrawn later.
-      if (wp->w_redr_type < UPD_VALID) {
+      if (!redraw_not_allowed && wp->w_redr_type < UPD_VALID) {
         wp->w_redr_type = UPD_VALID;
       }
 
@@ -390,9 +390,7 @@ static void changed_common(buf_T *buf, linenr_T lnum, colnr_T col, linenr_T lnum
 
   // Call update_screen() later, which checks out what needs to be redrawn,
   // since it notices b_mod_set and then uses b_mod_*.
-  if (must_redraw < UPD_VALID) {
-    must_redraw = UPD_VALID;
-  }
+  set_must_redraw(UPD_VALID);
 
   // when the cursor line is changed always trigger CursorMoved
   if (last_cursormoved_win == curwin && curwin->w_buffer == buf
diff --git a/src/nvim/drawscreen.c b/src/nvim/drawscreen.c
index 4df01d9476..7e1a453497 100644
--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@@ -2647,7 +2647,7 @@ void redraw_later(win_T *wp, int type)
 {
   // curwin may have been set to NULL when exiting
   assert(wp != NULL || exiting);
-  if (!exiting && wp->w_redr_type < type) {
+  if (!exiting && !redraw_not_allowed && wp->w_redr_type < type) {
     wp->w_redr_type = type;
     if (type >= UPD_NOT_VALID) {
       wp->w_lines_valid = 0;
@@ -2665,7 +2665,14 @@ void redraw_all_later(int type)
     redraw_later(wp, type);
   }
   // This may be needed when switching tabs.
-  if (must_redraw < type) {
+  set_must_redraw(type);
+}
+
+/// Set "must_redraw" to "type" unless it already has a higher value
+/// or it is currently not allowed.
+void set_must_redraw(int type)
+{
+  if (!redraw_not_allowed && must_redraw < type) {
     must_redraw = type;
   }
 }
@@ -2730,9 +2737,7 @@ void redraw_buf_status_later(buf_T *buf)
             || (wp == curwin && global_stl_height())
             || wp->w_winbar_height)) {
       wp->w_redr_status = true;
-      if (must_redraw < UPD_VALID) {
-        must_redraw = UPD_VALID;
-      }
+      set_must_redraw(UPD_VALID);
     }
   }
 }
diff --git a/src/nvim/drawscreen.h b/src/nvim/drawscreen.h
index 1f6f41fae2..f804345bca 100644
--- a/src/nvim/drawscreen.h
+++ b/src/nvim/drawscreen.h
@@ -21,6 +21,10 @@ enum {
 /// ('lines' and 'rows') must not be changed.
 EXTERN bool updating_screen INIT( = false);
 
+/// While computing a statusline and the like we do not want any w_redr_type or
+/// must_redraw to be set.
+EXTERN bool redraw_not_allowed INIT( = false);
+
 EXTERN match_T screen_search_hl INIT( = { 0 });  ///< used for 'hlsearch' highlight matching
 
 #define W_ENDCOL(wp)   ((wp)->w_wincol + (wp)->w_width)
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 307fd480cc..8af5730ffe 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -902,9 +902,7 @@ static uint8_t *command_line_enter(int firstc, int count, int indent, bool clear
   // not get printed in the middle of it.
   msg_check();
   if (p_ch == 0 && !ui_has(kUIMessages)) {
-    if (must_redraw < UPD_VALID) {
-      must_redraw = UPD_VALID;
-    }
+    set_must_redraw(UPD_VALID);
   }
   msg_scroll = s->save_msg_scroll;
   redir_off = false;
diff --git a/src/nvim/message.c b/src/nvim/message.c
index d879fa1423..b4e1d61cc7 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -2419,9 +2419,7 @@ static void inc_msg_scrolled(void)
     xfree(tofree);
   }
   msg_scrolled++;
-  if (must_redraw < UPD_VALID) {
-    must_redraw = UPD_VALID;
-  }
+  set_must_redraw(UPD_VALID);
 }
 
 static msgchunk_T *last_msgchunk = NULL;  // last displayed text
@@ -3067,9 +3065,7 @@ void msg_ext_clear_later(void)
 {
   if (msg_ext_is_visible()) {
     msg_ext_need_clear = true;
-    if (must_redraw < UPD_VALID) {
-      must_redraw = UPD_VALID;
-    }
+    set_must_redraw(UPD_VALID);
   }
 }
 
diff --git a/src/nvim/statusline.c b/src/nvim/statusline.c
index 0a716067c6..b403f840ca 100644
--- a/src/nvim/statusline.c
+++ b/src/nvim/statusline.c
@@ -935,14 +935,20 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, OptIndex op
   char buf_tmp[TMPLEN];
   char win_tmp[TMPLEN];
   char *usefmt = fmt;
-  const int save_must_redraw = must_redraw;
-  const int save_redr_type = curwin->w_redr_type;
+  const bool save_redraw_not_allowed = redraw_not_allowed;
   const bool save_KeyTyped = KeyTyped;
   // TODO(Bram): find out why using called_emsg_before makes tests fail, does it
   // matter?
   // const int called_emsg_before = called_emsg;
   const int did_emsg_before = did_emsg;
 
+  // When inside update_screen() we do not want redrawing a statusline,
+  // ruler, title, etc. to trigger another redraw, it may cause an endless
+  // loop.
+  if (updating_screen) {
+    redraw_not_allowed = true;
+  }
+
   if (stl_items == NULL) {
     stl_items = xmalloc(sizeof(stl_item_t) * stl_items_len);
     stl_groupitems = xmalloc(sizeof(int) * stl_items_len);
@@ -1938,16 +1944,16 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, OptIndex op
       stl_items[curitem].type = Empty;
     }
 
+    if (num >= 0 || (!itemisflag && str && *str)) {
+      prevchar_isflag = false;              // Item not NULL, but not a flag
+    }
+
     // Only free the string buffer if we allocated it.
     // Note: This is not needed if `str` is pointing at `tmp`
     if (opt == STL_VIM_EXPR) {
       XFREE_CLEAR(str);
     }
 
-    if (num >= 0 || (!itemisflag && str && *str)) {
-      prevchar_isflag = false;              // Item not NULL, but not a flag
-    }
-
     // Item processed, move to the next
     curitem++;
   }
@@ -2172,12 +2178,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, OptIndex op
     cur_tab_rec->def.func = NULL;
   }
 
-  // When inside update_screen we do not want redrawing a statusline, ruler,
-  // title, etc. to trigger another redraw, it may cause an endless loop.
-  if (updating_screen) {
-    must_redraw = save_must_redraw;
-    curwin->w_redr_type = save_redr_type;
-  }
+  redraw_not_allowed = save_redraw_not_allowed;
 
   // Check for an error.  If there is one the display will be messed up and
   // might loop redrawing.  Avoid that by making the corresponding option
diff --git a/src/nvim/winfloat.c b/src/nvim/winfloat.c
index 83a04a1bcf..8fe0315230 100644
--- a/src/nvim/winfloat.c
+++ b/src/nvim/winfloat.c
@@ -184,7 +184,7 @@ void win_config_float(win_T *wp, WinConfig fconfig)
   }
 
   win_set_inner_size(wp, true);
-  must_redraw = MAX(must_redraw, UPD_VALID);
+  set_must_redraw(UPD_VALID);
 
   wp->w_pos_changed = true;
   if (change_external || change_border) {