vim-patch:9.0.0965: using one window for executing autocommands is insufficient

Problem:    Using one window for executing autocommands is insufficient.
Solution:   Use up to five windows for executing autocommands.

https://github.com/vim/vim/commit/e76062c078debed0df818f70e4db14ad7a7cb53a

N/A patches for version.c:

vim-patch:9.0.0966: some compilers don't allow a declaration after a label

Problem:    Some compilers don't allow a declaration after a label.
Solution:   Move the declaration to the start of the block. (John Marriott)

https://github.com/vim/vim/commit/f86490ed4fdab213a28f667abd055c023a73d645

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

3 files changed, 14 insertions, 8 deletions

diff --git a/src/nvim/eval/buffer.c b/src/nvim/eval/buffer.c
index 72eb0f8d67..6ebf54ef0f 100644
--- a/src/nvim/eval/buffer.c
+++ b/src/nvim/eval/buffer.c
@@ -86,6 +86,8 @@ static void find_win_for_curbuf(void)
 ///
 /// Information is saved in "cob" and MUST be restored by calling
 /// change_other_buffer_restore().
+///
+/// If this fails then "curbuf" will not be equal to "buf".
 static void change_other_buffer_prepare(cob_T *cob, buf_T *buf)
 {
   CLEAR_POINTER(cob);
@@ -103,7 +105,9 @@ static void change_other_buffer_prepare(cob_T *cob, buf_T *buf)
     // curwin->w_buffer differ from "curbuf", use the autocmd window.
     curbuf = curwin->w_buffer;
     aucmd_prepbuf(&cob->cob_aco, buf);
-    cob->cob_using_aco = true;
+    if (curbuf == buf) {
+      cob->cob_using_aco = true;
+    }
   }
 }
 
diff --git a/src/nvim/eval/vars.c b/src/nvim/eval/vars.c
index 5459eac5bf..f002071ad2 100644
--- a/src/nvim/eval/vars.c
+++ b/src/nvim/eval/vars.c
@@ -1800,13 +1800,15 @@ void f_setbufvar(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     if (*varname == '&') {
       aco_save_T aco;
 
-      // set curbuf to be our buf, temporarily
+      // Set curbuf to be our buf, temporarily.
       aucmd_prepbuf(&aco, buf);
+      if (curbuf == buf) {
+        // Only when it worked to set "curbuf".
+        set_option_from_tv(varname + 1, varp);
 
-      set_option_from_tv(varname + 1, varp);
-
-      // reset notion of buffer
-      aucmd_restbuf(&aco);
+        // reset notion of buffer
+        aucmd_restbuf(&aco);
+      }
     } else {
       const size_t varname_len = strlen(varname);
       char *const bufvarname = xmalloc(varname_len + 3);
diff --git a/src/nvim/eval/window.c b/src/nvim/eval/window.c
index d6c761bc66..7cb346216d 100644
--- a/src/nvim/eval/window.c
+++ b/src/nvim/eval/window.c
@@ -590,7 +590,7 @@ static void win_move_into_split(win_T *wp, win_T *targetwin, int size, int flags
   int height = wp->w_height;
   win_T *oldwin = curwin;
 
-  if (wp == targetwin || wp == aucmd_win) {
+  if (wp == targetwin || is_aucmd_win(wp)) {
     return;
   }
 
@@ -674,7 +674,7 @@ void f_win_gettype(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
       return;
     }
   }
-  if (wp == aucmd_win) {
+  if (is_aucmd_win(wp)) {
     rettv->vval.v_string = xstrdup("autocmd");
   } else if (wp->w_p_pvw) {
     rettv->vval.v_string = xstrdup("preview");