fix(win): respect window size constraints and separator state

glepnir · seandewar · glepnir · commit ad18b3f95cc5 · 2025-09-04T14:30:39.000+08:00
Problem:
1. Rightmost window retained vsep after adjacent window closed
2. Explicit width/height ignored due to win_equal() override
3. winfixwidth windows expanded when receiving space from closed windows

Solution:
1. Clear vsep_width for new lastwin in win_remove()
2. Add WSP_NOEQUAL flag to skip equalization when size explicitly set
3. Skip frame resizing for winfixwidth windows in winframe_remove()

Co-authored-by: Sean Dewar &lt;6256228+seandewar@users.noreply.github.com&gt;
diff --git a/src/nvim/api/win_config.c b/src/nvim/api/win_config.c
@@ -260,6 +260,9 @@ Window nvim_open_win(Buffer buffer, Boolean enter, Dict(win_config) *config, Err
       }
     }
     int flags = win_split_flags(fconfig.split, parent == NULL) | WSP_NOENTER;
+    if (config->width != 0 || config->height != 0) {
+      flags |= WSP_NOEQUAL;
+    }
 
     TRY_WRAP(err, {
       int size = (flags & WSP_VERT) ? fconfig.width : fconfig.height;
diff --git a/src/nvim/window.c b/src/nvim/window.c
@@ -1440,7 +1440,7 @@ win_T *win_split_ins(int size, int flags, win_T *new_wp, int dir, frame_T *to_fl
     }
     if (toplevel) {
       if (flags & WSP_BOT) {
-        frame_add_vsep(curfrp);
+        frame_set_vsep(curfrp, true);
       }
       // Set width of neighbor frame
       frame_new_width(curfrp, curfrp->fr_width
@@ -1547,7 +1547,7 @@ win_T *win_split_ins(int size, int flags, win_T *new_wp, int dir, frame_T *to_fl
   }
 
   // equalize the window sizes.
-  if (do_equal || dir != 0) {
+  if ((do_equal || dir != 0) && !(flags & WSP_NOEQUAL)) {
     win_equal(wp, true, vertical ? (dir == 'v' ? 'b' : 'h') : (dir == 'h' ? 'b' : 'v'));
   } else if (!is_aucmd_win(wp)) {
     win_fix_scroll(false);
@@ -3218,6 +3218,12 @@ win_T *winframe_remove(win_T *win, int *dirp, tabpage_T *tp, frame_T **unflat_al
   int row = topleft->w_winrow;
   int col = topleft->w_wincol;
 
+  // If this is a rightmost window, remove vertical separators to the left.
+  if (win->w_vsep_width == 0 && frp_close->fr_parent->fr_layout == FR_ROW
+      && frp_close->fr_prev != NULL) {
+    frame_set_vsep(frp_close->fr_prev, false);
+  }
+
   // Remove this frame from the list of frames.
   frame_remove(frp_close);
 
@@ -3409,7 +3415,7 @@ void winframe_restore(win_T *wp, int dir, frame_T *unflat_altfr)
 
   // Vertical separators to the left may have been lost.  Restore them.
   if (wp->w_vsep_width == 0 && frp->fr_parent->fr_layout == FR_ROW && frp->fr_prev != NULL) {
-    frame_add_vsep(frp->fr_prev);
+    frame_set_vsep(frp->fr_prev, true);
   }
 
   // Statuslines or horizontal separators above may have been lost.  Restore them.
@@ -3855,23 +3861,26 @@ static void frame_new_width(frame_T *topfrp, int width, bool leftfirst, bool wfw
   topfrp->fr_width = width;
 }
 
-/// Add the vertical separator to windows at the right side of "frp".
+/// Add or remove the vertical separator to windows at the right side of "frp".
 /// Note: Does not check if there is room!
-static void frame_add_vsep(const frame_T *frp)
+static void frame_set_vsep(const frame_T *frp, bool add)
   FUNC_ATTR_NONNULL_ARG(1)
 {
   if (frp->fr_layout == FR_LEAF) {
     win_T *wp = frp->fr_win;
-    if (wp->w_vsep_width == 0) {
+    if (add && wp->w_vsep_width == 0) {
       if (wp->w_width > 0) {            // don't make it negative
         wp->w_width--;
       }
       wp->w_vsep_width = 1;
+    } else if (!add && wp->w_vsep_width == 1) {
+      win_new_width(wp, wp->w_width + 1);
+      wp->w_vsep_width = 0;
     }
   } else if (frp->fr_layout == FR_COL) {
     // Handle all the frames in the column.
     FOR_ALL_FRAMES(frp, frp->fr_child) {
-      frame_add_vsep(frp);
+      frame_set_vsep(frp, add);
     }
   } else {
     assert(frp->fr_layout == FR_ROW);
@@ -3880,7 +3889,7 @@ static void frame_add_vsep(const frame_T *frp)
     while (frp->fr_next != NULL) {
       frp = frp->fr_next;
     }
-    frame_add_vsep(frp);
+    frame_set_vsep(frp, add);
   }
 }
 
diff --git a/src/nvim/window.h b/src/nvim/window.h
@@ -20,6 +20,7 @@ enum {
   WSP_ABOVE   = 0x80,   ///< put new window above/left
   WSP_NEWLOC  = 0x100,  ///< don't copy location list
   WSP_NOENTER = 0x200,  ///< don't enter the new window
+  WSP_NOEQUAL = 0x400,  ///< don't equalize the new window
 };
 
 enum {
diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
@@ -2259,6 +2259,44 @@ describe('API/win', function()
       )
       eq(true, eval 'nvim_tabpage_is_valid(g:tp)')
     end)
+    it('removes vsep from new lastwin when rightmost window closed #32854', function()
+      local screen = Screen.new(50, 10)
+      exec_lua([[
+        local win1 = vim.api.nvim_open_win(0, false, { win = -1, split = "right", width=20})
+        vim.api.nvim_set_option_value("winfixwidth", true, { win = win1 })
+        local win2 = nil
+        local toggle_win2 = function()
+          if win2 == nil then
+            win2 = vim.api.nvim_open_win(0, false, { win = -1, split = "right", width=20})
+          else
+            vim.api.nvim_win_close(win2, true)
+            win2 = nil
+          end
+        end
+        vim.keymap.set("n", "w", toggle_win2)
+        vim.o.winbar = "%{%v:lua.wn()%}"
+        _G.wn = function()
+          return vim.api.nvim_get_current_win()
+        end
+      ]])
+      feed('w')
+      local wins = api.nvim_list_wins()
+      eq(20, api.nvim_win_get_width(wins[#wins]))
+      feed('w')
+      screen:expect([[
+        {5:1000                        }│{5:1001                 }|
+        ^                            │                     |
+        {1:~                           }│{1:~                    }|*6
+        {3:[No Name]                    }{2:[No Name]            }|
+                                                          |
+      ]])
+      feed('wwwww')
+      wins = api.nvim_list_wins()
+      eq(
+        { 20, 20 },
+        { api.nvim_win_get_width(wins[#wins]), api.nvim_win_get_width(wins[#wins - 1]) }
+      )
+    end)
   end)
 
   describe('set_config', function()

Original file line number	Diff line number	Diff line change
`@@ -260,6 +260,9 @@ Window nvim_open_win(Buffer buffer, Boolean enter, Dict(win_config) *config, Err`
`260`	`260`	`}`
`261`	`261`	`}`
`262`	`262`	`int flags = win_split_flags(fconfig.split, parent == NULL) \| WSP_NOENTER;`
	`263`	`+ if (config->width != 0 \|\| config->height != 0) {`
	`264`	`+ flags \|= WSP_NOEQUAL;`
	`265`	`+ }`
`263`	`266`
`264`	`267`	`TRY_WRAP(err, {`
`265`	`268`	`int size = (flags & WSP_VERT) ? fconfig.width : fconfig.height;`