From 0ee8323f2b5c95e4c0efc5c055f840d6223a1515 Mon Sep 17 00:00:00 2001
From: Sean Dewar <6256228+seandewar@users.noreply.github.com>
Date: Mon, 9 Mar 2026 00:31:04 +0000
Subject: [PATCH] fix(api): unnecessary errors when not moving split

Problem: nvim_win_set_config may raise unnecessary errors when not moving a
split.

Solution: skip checks related to moving when only maybe resizing a split.
---
 src/nvim/api/win_config.c           | 38 ++++++++++++++---------------
 test/functional/api/window_spec.lua | 15 ++++++++++++
 2 files changed, 34 insertions(+), 19 deletions(-)

diff --git a/src/nvim/api/win_config.c b/src/nvim/api/win_config.c
index 7ea46d9059..52011a3fbe 100644
--- a/src/nvim/api/win_config.c
+++ b/src/nvim/api/win_config.c
@@ -392,6 +392,25 @@ static bool win_config_split(win_T *win, Dict(win_config) *config, WinConfig *fc
   FUNC_ATTR_NONNULL_ALL
 {
 #define HAS_KEY_X(d, key) HAS_KEY(d, win_config, key)
+  bool was_split = !win->w_floating;
+  bool has_split = HAS_KEY_X(config, split);
+  bool has_vertical = HAS_KEY_X(config, vertical);
+  WinSplit old_split = win_split_dir(win);
+  if (has_vertical && !has_split) {
+    if (config->vertical) {
+      fconfig->split = (old_split == kWinSplitRight || p_spr) ? kWinSplitRight : kWinSplitLeft;
+    } else {
+      fconfig->split = (old_split == kWinSplitBelow || p_sb) ? kWinSplitBelow : kWinSplitAbove;
+    }
+  }
+
+  // If there's no "vertical" or "split" set, or if "split" is unchanged, then we can just change
+  // the size of the window.
+  if ((!has_vertical && !has_split)
+      || (was_split && !HAS_KEY_X(config, win) && old_split == fconfig->split)) {
+    goto resize;
+  }
+
   win_T *parent = NULL;
   tabpage_T *parent_tp = NULL;
   if (config->win == 0) {
@@ -422,25 +441,6 @@ static bool win_config_split(win_T *win, Dict(win_config) *config, WinConfig *fc
     }
   }
 
-  bool was_split = !win->w_floating;
-  bool has_split = HAS_KEY_X(config, split);
-  bool has_vertical = HAS_KEY_X(config, vertical);
-  WinSplit old_split = win_split_dir(win);
-  if (has_vertical && !has_split) {
-    if (config->vertical) {
-      fconfig->split = (old_split == kWinSplitRight || p_spr) ? kWinSplitRight : kWinSplitLeft;
-    } else {
-      fconfig->split = (old_split == kWinSplitBelow || p_sb) ? kWinSplitBelow : kWinSplitAbove;
-    }
-  }
-
-  // If there's no "vertical" or "split" set, or if "split" is unchanged, then we can just change
-  // the size of the window.
-  if ((!has_vertical && !has_split)
-      || (was_split && !HAS_KEY_X(config, win) && old_split == fconfig->split)) {
-    goto resize;
-  }
-
   if (!check_split_disallowed_err(win, err)) {
     return false;  // error already set
   }
diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
index d6178fcfb1..6c435efd7c 100644
--- a/test/functional/api/window_spec.lua
+++ b/test/functional/api/window_spec.lua
@@ -3524,6 +3524,21 @@ describe('API/win', function()
         'Cannot split a floating window',
         pcall_err(api.nvim_win_set_config, win, { win = 0, split = 'right' })
       )
+
+      -- No errors when not actually splitting.
+      local cfg = api.nvim_win_get_config(win)
+      api.nvim_win_set_config(win, {})
+      eq(cfg, api.nvim_win_get_config(win))
+
+      eq(1, eval('&cmdheight'))
+      api.nvim_win_set_config(win, { height = 1 })
+      cfg.height = 1
+      eq(cfg, api.nvim_win_get_config(win))
+      eq(23, eval('&cmdheight'))
+
+      api.nvim_win_set_config(win, { style = 'minimal' })
+      cfg.style = 'minimal'
+      eq(cfg, api.nvim_win_get_config(win))
     end)
 
     it('cannot move autocmd window between tabpages', function()