feat(api): allow floats to be opened in non-current tabpage (#28480)

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runtime/doc/news.txt

@@ -478,7 +478,8 @@ The following changes to existing APIs or features add new behavior.
   |:vertical|, |:horizontal| and |:botright|.
 
 • |nvim_open_win()| and |nvim_win_set_config()| now support opening normal (split)
-  windows, and moving floating windows into split windows.
+  windows, moving floating windows into split windows, and opening windows in
+  non-current tabpages.
 
 • 'errorfile' (|-q|) accepts `-` as an alias for stdin.
 

src/nvim/api/win_config.c

@@ -236,19 +236,19 @@ Window nvim_open_win(Buffer buffer, Boolean enter, Dict(win_config) *config, Err
 
   win_T *wp = NULL;
   tabpage_T *tp = curtab;
-  if (is_split) {
-    win_T *parent = NULL;
-    if (config->win != -1) {
-      parent = find_window_by_handle(fconfig.window, err);
-      if (!parent) {
-        // find_window_by_handle has already set the error
-        goto cleanup;
-      } else if (parent->w_floating) {
-        api_set_error(err, kErrorTypeException, "Cannot split a floating window");
-        goto cleanup;
-      }
+  win_T *parent = NULL;
+  if (config->win != -1) {
+    parent = find_window_by_handle(fconfig.window, err);
+    if (!parent) {
+      // find_window_by_handle has already set the error
+      goto cleanup;
+    } else if (is_split && parent->w_floating) {
+      api_set_error(err, kErrorTypeException, "Cannot split a floating window");
+      goto cleanup;
     }
-
+    tp = win_find_tabpage(parent);
+  }
+  if (is_split) {
     if (!check_split_disallowed_err(parent ? parent : curwin, err)) {
       goto cleanup;  // error already set
     }
@@ -267,7 +267,6 @@ Window nvim_open_win(Buffer buffer, Boolean enter, Dict(win_config) *config, Err
       if (parent == NULL || parent == curwin) {
         wp = win_split_ins(size, flags, NULL, 0, NULL);
       } else {
-        tp = win_find_tabpage(parent);
         switchwin_T switchwin;
         // `parent` is valid in `tp`, so switch_win should not fail.
         const int result = switch_win(&switchwin, parent, tp, true);
@@ -395,6 +394,7 @@ void nvim_win_set_config(Window window, Dict(win_config) *config, Error *err)
   if (!win) {
     return;
   }
+
   tabpage_T *win_tp = win_find_tabpage(win);
   bool was_split = !win->w_floating;
   bool has_split = HAS_KEY_X(config, split);
@@ -409,23 +409,28 @@ void nvim_win_set_config(Window window, Dict(win_config) *config, Error *err)
   if (!parse_win_config(win, config, &fconfig, !was_split || to_split, err)) {
     return;
   }
+  win_T *parent = NULL;
+  if (config->win != -1) {
+    parent = find_window_by_handle(fconfig.window, err);
+    if (!parent) {
+      return;
+    } else if (to_split && parent->w_floating) {
+      api_set_error(err, kErrorTypeException, "Cannot split a floating window");
+      return;
+    }
+
+    // Prevent autocmd window from being moved into another tabpage
+    if (is_aucmd_win(win) && win_find_tabpage(win) != win_find_tabpage(parent)) {
+      api_set_error(err, kErrorTypeException, "Cannot move autocmd win to another tabpage");
+      return;
+    }
+  }
   if (was_split && !to_split) {
     if (!win_new_float(win, false, fconfig, err)) {
       return;
     }
     redraw_later(win, UPD_NOT_VALID);
   } else if (to_split) {
-    win_T *parent = NULL;
-    if (config->win != -1) {
-      parent = find_window_by_handle(fconfig.window, err);
-      if (!parent) {
-        return;
-      } else if (parent->w_floating) {
-        api_set_error(err, kErrorTypeException, "Cannot split a floating window");
-        return;
-      }
-    }
-
     WinSplit old_split = win_split_dir(win);
     if (has_vertical && !has_split) {
       if (config->vertical) {

src/nvim/window.c

@@ -5127,7 +5127,14 @@ win_T *win_alloc(win_T *after, bool hidden)
   block_autocmds();
   // link the window in the window list
   if (!hidden) {
-    win_append(after, new_wp, NULL);
+    tabpage_T *tp = NULL;
+    if (after) {
+      tp = win_find_tabpage(after);
+      if (tp == curtab) {
+        tp = NULL;
+      }
+    }
+    win_append(after, new_wp, tp);
   }
 
   new_wp->w_wincol = 0;

src/nvim/winfloat.c

@@ -41,7 +41,24 @@
 win_T *win_new_float(win_T *wp, bool last, WinConfig fconfig, Error *err)
 {
   if (wp == NULL) {
-    wp = win_alloc(last ? lastwin : lastwin_nofloating(), false);
+    tabpage_T *tp = NULL;
+    win_T *tp_last = last ? lastwin : lastwin_nofloating();
+    if (fconfig.window != 0) {
+      assert(!last);
+      win_T *parent_wp = find_window_by_handle(fconfig.window, err);
+      if (!parent_wp) {
+        return NULL;
+      }
+      tp = win_find_tabpage(parent_wp);
+      if (!tp) {
+        return NULL;
+      }
+      tp_last = tp->tp_lastwin;
+      while (tp_last->w_floating && tp_last->w_prev) {
+        tp_last = tp_last->w_prev;
+      }
+    }
+    wp = win_alloc(tp_last, false);
     win_init(wp, curwin, 0);
   } else {
     assert(!last);

test/functional/api/window_spec.lua

@@ -1454,6 +1454,40 @@ describe('API/win', function()
       }, layout)
     end)
 
+    it('opens floating windows in other tabpages', function()
+      local first_win = api.nvim_get_current_win()
+      local first_tab = api.nvim_get_current_tabpage()
+
+      command('tabnew')
+      local new_tab = api.nvim_get_current_tabpage()
+      local win = api.nvim_open_win(0, false, {
+        relative = 'win',
+        win = first_win,
+        width = 5,
+        height = 5,
+        row = 1,
+        col = 1,
+      })
+      eq(api.nvim_win_get_tabpage(win), first_tab)
+      eq(api.nvim_get_current_tabpage(), new_tab)
+    end)
+
+    it('switches to new windows in non-current tabpages when enter=true', function()
+      local first_win = api.nvim_get_current_win()
+      local first_tab = api.nvim_get_current_tabpage()
+      command('tabnew')
+      local win = api.nvim_open_win(0, true, {
+        relative = 'win',
+        win = first_win,
+        width = 5,
+        height = 5,
+        row = 1,
+        col = 1,
+      })
+      eq(api.nvim_win_get_tabpage(win), first_tab)
+      eq(api.nvim_get_current_tabpage(), first_tab)
+    end)
+
     local function setup_tabbed_autocmd_test()
       local info = {}
       info.orig_buf = api.nvim_get_current_buf()

test/functional/ui/float_spec.lua

@@ -532,7 +532,10 @@ describe('float window', function()
     local closed_win = api.nvim_get_current_win()
     command('close')
     local buf = api.nvim_create_buf(false,false)
-    api.nvim_open_win(buf, true, {relative='win', win=closed_win, width=1, height=1, bufpos={0,0}})
+    eq(
+      'Invalid window id: ' .. closed_win,
+      pcall_err(api.nvim_open_win, buf, true, {relative='win', win=closed_win, width=1, height=1, bufpos={0,0}})
+    )
     assert_alive()
   end)