api(nvim_open_win): add "noautocmd" option

This option, when set, stops nvim_open_win() from potentially firing
buffer-related autocmd events
(BufEnter, BufLeave and BufWinEnter in the case of nvim_open_win()).

src/nvim/api/private/helpers.c

@@ -1645,7 +1645,7 @@ bool api_object_to_bool(Object obj, const char *what,
   } else if (obj.type == kObjectTypeNil) {
     return nil_value;  // caller decides what NIL (missing retval in lua) means
   } else {
-    api_set_error(err, kErrorTypeValidation, "%s is not an boolean", what);
+    api_set_error(err, kErrorTypeValidation, "%s is not a boolean", what);
     return false;
   }
 }
@@ -1868,7 +1868,7 @@ static void parse_border_style(Object style, FloatConfig *fconfig, Error *err)
 }
 
 bool parse_float_config(Dictionary config, FloatConfig *fconfig, bool reconf,
-                        Error *err)
+                        bool new_win, Error *err)
 {
   // TODO(bfredl): use a get/has_key interface instead and get rid of extra
   // flags
@@ -2015,6 +2015,12 @@ bool parse_float_config(Dictionary config, FloatConfig *fconfig, bool reconf,
         api_set_error(err, kErrorTypeValidation,
                       "Invalid value of 'style' key");
       }
+    } else if (strequal(key, "noautocmd") && new_win) {
+      fconfig->noautocmd
+          = api_object_to_bool(val, "'noautocmd' key", false, err);
+      if (ERROR_SET(err)) {
+        return false;
+      }
     } else {
       api_set_error(err, kErrorTypeValidation,
                     "Invalid key '%s'", key);

src/nvim/api/vim.c

@@ -1459,6 +1459,9 @@ void nvim_chan_send(Integer chan, String data, Error *err)
 ///     By default `FloatBorder` highlight is used which links to `VertSplit`
 ///     when not defined.  It could also be specified by character:
 ///       [ {"+", "MyCorner"}, {"x", "MyBorder"} ]
+///   - `noautocmd`: If true then no buffer-related autocommand events such as
+///                  |BufEnter|, |BufLeave| or |BufWinEnter| may fire from
+///                  calling this function.
 ///
 /// @param[out] err Error details, if any
 ///
@@ -1469,7 +1472,7 @@ Window nvim_open_win(Buffer buffer, Boolean enter, Dictionary config,
   FUNC_API_CHECK_TEXTLOCK
 {
   FloatConfig fconfig = FLOAT_CONFIG_INIT;
-  if (!parse_float_config(config, &fconfig, false, err)) {
+  if (!parse_float_config(config, &fconfig, false, true, err)) {
     return 0;
   }
   win_T *wp = win_new_float(NULL, fconfig, err);
@@ -1484,7 +1487,7 @@ Window nvim_open_win(Buffer buffer, Boolean enter, Dictionary config,
     return 0;
   }
   if (buffer > 0) {
-    nvim_win_set_buf(wp->handle, buffer, err);
+    win_set_buf(wp->handle, buffer, fconfig.noautocmd, err);
   }
 
   if (fconfig.style == kWinStyleMinimal) {

src/nvim/api/window.c

@@ -46,35 +46,7 @@ void nvim_win_set_buf(Window window, Buffer buffer, Error *err)
   FUNC_API_SINCE(5)
   FUNC_API_CHECK_TEXTLOCK
 {
-  win_T *win = find_window_by_handle(window, err), *save_curwin = curwin;
-  buf_T *buf = find_buffer_by_handle(buffer, err);
-  tabpage_T *tab = win_find_tabpage(win), *save_curtab = curtab;
-
-  if (!win || !buf) {
-    return;
-  }
-
-  if (switch_win(&save_curwin, &save_curtab, win, tab, false) == FAIL) {
-    api_set_error(err,
-                  kErrorTypeException,
-                  "Failed to switch to window %d",
-                  window);
-  }
-
-  try_start();
-  int result = do_buffer(DOBUF_GOTO, DOBUF_FIRST, FORWARD, buf->b_fnum, 0);
-  if (!try_end(err) && result == FAIL) {
-    api_set_error(err,
-                  kErrorTypeException,
-                  "Failed to set buffer %d",
-                  buffer);
-  }
-
-  // If window is not current, state logic will not validate its cursor.
-  // So do it now.
-  validate_cursor();
-
-  restore_win(save_curwin, save_curtab, false);
+  win_set_buf(window, buffer, false, err);
 }
 
 /// Gets the (1,0)-indexed cursor position in the window. |api-indexing|
@@ -423,7 +395,7 @@ void nvim_win_set_config(Window window, Dictionary config, Error *err)
   // reuse old values, if not overriden
   FloatConfig fconfig = new_float ? FLOAT_CONFIG_INIT : win->w_float_config;
 
-  if (!parse_float_config(config, &fconfig, !new_float, err)) {
+  if (!parse_float_config(config, &fconfig, !new_float, false, err)) {
     return;
   }
   if (new_float) {