vim-patch:8.0.1073: may get an endless loop if 'statusline' changes a highlight

Problem:    May get an endless loop if 'statusline' changes a highlight.
Solution:   Do not let evaluating 'statusline' trigger a redraw.
https://github.com/vim/vim/commit/ba2929b6afd2fc20479912a8dec789be26a38244

1 files changed, 14 insertions, 4 deletions

diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 7b90cbe4f4..802eba06a5 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -3224,6 +3224,9 @@ int build_stl_str_hl(
 #define TMPLEN 70
   char_u tmp[TMPLEN];
   char_u      *usefmt = fmt;
+  const int save_must_redraw = must_redraw;
+  const int save_redr_type = curwin->w_redr_type;
+  const int save_highlight_shcnaged = need_highlight_changed;
 
   // When the format starts with "%!" then evaluate it as an expression and
   // use the result as the actual format string.
@@ -3632,16 +3635,16 @@ int build_stl_str_hl(
       vim_snprintf((char *)tmp, sizeof(tmp), "%d", curbuf->b_fnum);
       set_internal_string_var((char_u *)"g:actual_curbuf", tmp);
 
-      buf_T *o_curbuf = curbuf;
-      win_T *o_curwin = curwin;
+      buf_T *const save_curbuf = curbuf;
+      win_T *const save_curwin = curwin;
       curwin = wp;
       curbuf = wp->w_buffer;
 
       // Note: The result stored in `t` is unused.
       str = eval_to_string_safe(out_p, &t, use_sandbox);
 
-      curwin = o_curwin;
-      curbuf = o_curbuf;
+      curwin = save_curwin;
+      curbuf = save_curbuf;
 
       // Remove the variable we just stored
       do_unlet(S_LEN("g:actual_curbuf"), true);
@@ -4262,6 +4265,13 @@ int build_stl_str_hl(
     cur_tab_rec->def.func = NULL;
   }
 
+  // We do not want redrawing a stausline, ruler, title, etc. to trigger
+  // another redraw, it may cause an endless loop.  This happens when a
+  // statusline changes a highlight group.
+  must_redraw = save_must_redraw;
+  curwin->w_redr_type = save_redr_type;
+  need_highlight_changed = save_highlight_shcnaged;
+
   return width;
 }