feat(aucmd_win): allow crazy things with hidden buffers (#21250)

Problem:    Crash when doing crazy things with hidden buffers.
Solution:   Dynamically allocate the list of autocommand windows.

1 files changed, 12 insertions, 22 deletions

diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 2060f799bd..c9fe5f9670 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -181,13 +181,11 @@ void buffer_ensure_loaded(buf_T *buf)
   if (buf->b_ml.ml_mfp == NULL) {
     aco_save_T aco;
 
-    // Make sure the buffer is in a window.  If not then skip it.
+    // Make sure the buffer is in a window.
     aucmd_prepbuf(&aco, buf);
-    if (curbuf == buf) {
-      swap_exists_action = SEA_NONE;
-      open_buffer(false, NULL, 0);
-      aucmd_restbuf(&aco);
-    }
+    swap_exists_action = SEA_NONE;
+    open_buffer(false, NULL, 0);
+    aucmd_restbuf(&aco);
   }
 }
 
@@ -369,20 +367,17 @@ int open_buffer(int read_stdin, exarg_T *eap, int flags_arg)
     aco_save_T aco;
 
     // Go to the buffer that was opened, make sure it is in a window.
-    // If not then skip it.
     aucmd_prepbuf(&aco, old_curbuf.br_buf);
-    if (curbuf == old_curbuf.br_buf) {
-      do_modelines(0);
-      curbuf->b_flags &= ~(BF_CHECK_RO | BF_NEVERLOADED);
-
-      if ((flags & READ_NOWINENTER) == 0) {
-        apply_autocmds_retval(EVENT_BUFWINENTER, NULL, NULL, false, curbuf,
-                              &retval);
-      }
+    do_modelines(0);
+    curbuf->b_flags &= ~(BF_CHECK_RO | BF_NEVERLOADED);
 
-      // restore curwin/curbuf and a few other things
-      aucmd_restbuf(&aco);
+    if ((flags & READ_NOWINENTER) == 0) {
+      apply_autocmds_retval(EVENT_BUFWINENTER, NULL, NULL, false, curbuf,
+                            &retval);
     }
+
+    // restore curwin/curbuf and a few other things
+    aucmd_restbuf(&aco);
   }
 
   return retval;
@@ -4177,11 +4172,6 @@ bool buf_contents_changed(buf_T *buf)
   // Set curwin/curbuf to buf and save a few things.
   aco_save_T aco;
   aucmd_prepbuf(&aco, newbuf);
-  if (curbuf != newbuf) {
-    // Failed to find a window for "newbuf".
-    wipe_buffer(newbuf, false);
-    return true;
-  }
 
   if (ml_open(curbuf) == OK
       && readfile(buf->b_ffname, buf->b_fname,