2 files changed, 75 insertions, 9 deletions

diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 24ad7d5fbc..43bf4eaf31 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -958,21 +958,21 @@ Buffer nvim_create_buf(Boolean listed, Boolean scratch, Error *err)
   FUNC_API_SINCE(6)
 {
   try_start();
+  // Block autocommands for now so they don't mess with the buffer before we
+  // finish configuring it.
+  block_autocmds();
+
   buf_T *buf = buflist_new(NULL, NULL, 0,
                            BLN_NOOPT | BLN_NEW | (listed ? BLN_LISTED : 0));
-  try_end(err);
   if (buf == NULL) {
+    unblock_autocmds();
     goto fail;
   }
 
   // Open the memline for the buffer. This will avoid spurious autocmds when
   // a later nvim_buf_set_lines call would have needed to "open" the buffer.
-  try_start();
-  block_autocmds();
-  int status = ml_open(buf);
-  unblock_autocmds();
-  try_end(err);
-  if (status == FAIL) {
+  if (ml_open(buf) == FAIL) {
+    unblock_autocmds();
     goto fail;
   }
 
@@ -983,7 +983,7 @@ Buffer nvim_create_buf(Boolean listed, Boolean scratch, Error *err)
   buf->b_last_changedtick_pum = buf_get_changedtick(buf);
 
   // Only strictly needed for scratch, but could just as well be consistent
-  // and do this now. buffer is created NOW, not when it latter first happen
+  // and do this now. Buffer is created NOW, not when it later first happens
   // to reach a window or aucmd_prepbuf() ..
   buf_copy_options(buf, BCO_ENTER | BCO_NOHELP);
 
@@ -994,10 +994,26 @@ Buffer nvim_create_buf(Boolean listed, Boolean scratch, Error *err)
     buf->b_p_swf = false;
     buf->b_p_ml = false;
   }
+
+  unblock_autocmds();
+
+  bufref_T bufref;
+  set_bufref(&bufref, buf);
+  if (apply_autocmds(EVENT_BUFNEW, NULL, NULL, false, buf)
+      && !bufref_valid(&bufref)) {
+    goto fail;
+  }
+  if (listed
+      && apply_autocmds(EVENT_BUFADD, NULL, NULL, false, buf)
+      && !bufref_valid(&bufref)) {
+    goto fail;
+  }
+
+  try_end(err);
   return buf->b_fnum;
 
 fail:
-  if (!ERROR_SET(err)) {
+  if (!try_end(err)) {
     api_set_error(err, kErrorTypeException, "Failed to create buffer");
   }
   return 0;
diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index 09a45242ec..ef602b3a51 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -3135,6 +3135,56 @@ describe('API', function()
       -- nowadays this works because we don't execute any spurious autocmds at all #24824
       assert_alive()
     end)
+
+    it('no memory leak when autocommands load the buffer immediately', function()
+      exec([[
+        autocmd BufNew * ++once call bufload(expand("<abuf>")->str2nr())
+                             \| let loaded = bufloaded(expand("<abuf>")->str2nr())
+      ]])
+      api.nvim_create_buf(false, true)
+      eq(1, eval('g:loaded'))
+    end)
+
+    it('creating scratch buffer where autocommands set &swapfile works', function()
+      exec([[
+        autocmd BufNew * ++once execute expand("<abuf>") "buffer"
+                             \| file foobar
+                             \| setlocal swapfile
+      ]])
+      local new_buf = api.nvim_create_buf(false, true)
+      neq('', fn.swapname(new_buf))
+    end)
+
+    it('fires expected autocommands', function()
+      exec([=[
+        " Append the &buftype to check autocommands trigger *after* the buffer was configured to be
+        " scratch, if applicable.
+        autocmd BufNew * let fired += [["BufNew", expand("<abuf>")->str2nr(),
+                                      \ getbufvar(expand("<abuf>")->str2nr(), "&buftype")]]
+        autocmd BufAdd * let fired += [["BufAdd", expand("<abuf>")->str2nr(),
+                                      \ getbufvar(expand("<abuf>")->str2nr(), "&buftype")]]
+
+        " Don't want to see OptionSet; buffer options set from passing true for "scratch", etc.
+        " should be configured invisibly, and before autocommands.
+        autocmd OptionSet * let fired += [["OptionSet", expand("<amatch>")]]
+
+        let fired = []
+      ]=])
+      local new_buf = api.nvim_create_buf(false, false)
+      eq({ { 'BufNew', new_buf, '' } }, eval('g:fired'))
+
+      command('let fired = []')
+      new_buf = api.nvim_create_buf(false, true)
+      eq({ { 'BufNew', new_buf, 'nofile' } }, eval('g:fired'))
+
+      command('let fired = []')
+      new_buf = api.nvim_create_buf(true, false)
+      eq({ { 'BufNew', new_buf, '' }, { 'BufAdd', new_buf, '' } }, eval('g:fired'))
+
+      command('let fired = []')
+      new_buf = api.nvim_create_buf(true, true)
+      eq({ { 'BufNew', new_buf, 'nofile' }, { 'BufAdd', new_buf, 'nofile' } }, eval('g:fired'))
+    end)
   end)
 
   describe('nvim_get_runtime_file', function()