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;
+  win_set_buf(window, buffer, false, err);
-  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);
 }
 
 /// 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) {

src/nvim/buffer_defs.h

@@ -1090,6 +1090,7 @@ typedef struct {
   schar_T border_chars[8];
   int border_hl_ids[8];
   int border_attr[8];
+  bool noautocmd;
 } FloatConfig;
 
 #define FLOAT_CONFIG_INIT ((FloatConfig){ .height = 0, .width = 0, \
@@ -1098,7 +1099,8 @@ typedef struct {
                                           .relative = 0, .external = false, \
                                           .focusable = true, \
                                           .zindex = kZIndexFloatDefault, \
-                                          .style = kWinStyleUnused })
+                                          .style = kWinStyleUnused, \
+                                          .noautocmd = false })
 
 // Structure to store last cursor position and topline.  Used by check_lnums()
 // and reset_lnums().

src/nvim/window.c

@@ -570,6 +570,45 @@ static void cmd_with_count(char *cmd, char_u *bufp, size_t bufsize,
   }
 }
 
+void win_set_buf(Window window, Buffer buffer, bool noautocmd, Error *err)
+{
+  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 (noautocmd) {
+    block_autocmds();
+  }
+  if (switch_win_noblock(&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_noblock(save_curwin, save_curtab, false);
+  if (noautocmd) {
+    unblock_autocmds();
+  }
+}
+
 /// Create a new float.
 ///
 /// if wp == NULL allocate a new window, otherwise turn existing window into a

test/functional/api/window_spec.lua

@@ -387,4 +387,18 @@ describe('API/win', function()
       eq({oldbuf}, meths.list_bufs())
     end)
   end)
+
+  describe('open_win', function()
+    it('noautocmd option works', function()
+      command('autocmd BufEnter,BufLeave,BufWinEnter * let g:fired = 1')
+      meths.open_win(meths.create_buf(true, true), true, {
+        relative='win', row=3, col=3, width=12, height=3, noautocmd=true
+      })
+      eq(0, funcs.exists('g:fired'))
+      meths.open_win(meths.create_buf(true, true), true, {
+        relative='win', row=3, col=3, width=12, height=3
+      })
+      eq(1, funcs.exists('g:fired'))
+    end)
+  end)
 end)