vim-patch:partial:9.1.0117: Stop split-moving from firing WinNew and WinNewPre autocommands

Problem:  win_splitmove fires WinNewPre and possibly WinNew when moving
          windows, even though no new windows are created.
Solution: don't fire WinNew and WinNewPre when inserting an existing
          window, even if it isn't the current window. Improve the
          accuracy of related documentation. (Sean Dewar)

https://github.com/vim/vim/commit/96cc4aef3d47d0fd70e68908af3d48a0dce8ea70

Partial as WinNewPre has not been ported yet (it currently has problems anyway).

6 files changed, 47 insertions, 29 deletions

diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index c5f3946871..4b1ccc0c5c 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -8901,10 +8901,10 @@ win_screenpos({nr})                                            *win_screenpos()*
 		tabpage.
 
 win_splitmove({nr}, {target} [, {options}])                    *win_splitmove()*
-		Move the window {nr} to a new split of the window {target}.
-		This is similar to moving to {target}, creating a new window
-		using |:split| but having the same contents as window {nr}, and
-		then closing {nr}.
+		Temporarily switch to window {target}, then move window {nr}
+		to a new split adjacent to {target}.
+		Unlike commands such as |:split|, no new windows are created
+		(the |window-ID| of window {nr} is unchanged after the move).
 
 		Both {nr} and {target} can be window numbers or |window-ID|s.
 		Both must be in the current tab page.
diff --git a/runtime/doc/windows.txt b/runtime/doc/windows.txt
index b71e7c80ab..4791e73929 100644
--- a/runtime/doc/windows.txt
+++ b/runtime/doc/windows.txt
@@ -502,35 +502,33 @@ horizontally split windows.  CTRL-W H does it the other way around.
 
 						*CTRL-W_K*
 CTRL-W K	Move the current window to be at the very top, using the full
-		width of the screen.  This works like closing the current
-		window and then creating another one with ":topleft split",
-		except that the current window contents is used for the new
-		window.
+		width of the screen.  This works like `:topleft split`, except
+		it is applied to the current window and no new window is
+		created.
 
 						*CTRL-W_J*
 CTRL-W J	Move the current window to be at the very bottom, using the
-		full width of the screen.  This works like closing the current
-		window and then creating another one with ":botright split",
-		except that the current window contents is used for the new
-		window.
+		full width of the screen.  This works like `:botright split`,
+		except it is applied to the current window and no new window
+		is created.
 
 						*CTRL-W_H*
 CTRL-W H	Move the current window to be at the far left, using the
-		full height of the screen.  This works like closing the
-		current window and then creating another one with
-		`:vert topleft split`, except that the current window contents
-		is used for the new window.
+		full height of the screen.  This works like
+		`:vert topleft split`, except it is applied to the current
+		window and no new window is created.
 
 						*CTRL-W_L*
 CTRL-W L	Move the current window to be at the far right, using the full
-		height of the screen.  This works like closing the
-		current window and then creating another one with
-		`:vert botright split`, except that the current window
-		contents is used for the new window.
+		height of the screen.  This works like `:vert botright split`,
+		except it is applied to the current window and no new window
+		is created.
 
 						*CTRL-W_T*
 CTRL-W T	Move the current window to a new tab page.  This fails if
 		there is only one window in the current tab page.
+		This works like `:tab split`, except the previous window is
+		closed.
 		When a count is specified the new tab page will be opened
 		before the tab page with this index.  Otherwise it comes after
 		the current tab page.
diff --git a/runtime/lua/vim/_meta/vimfn.lua b/runtime/lua/vim/_meta/vimfn.lua
index ac25547212..ee68f669f8 100644
--- a/runtime/lua/vim/_meta/vimfn.lua
+++ b/runtime/lua/vim/_meta/vimfn.lua
@@ -10598,10 +10598,10 @@ function vim.fn.win_move_statusline(nr, offset) end
 --- @return any
 function vim.fn.win_screenpos(nr) end
 
---- Move the window {nr} to a new split of the window {target}.
---- This is similar to moving to {target}, creating a new window
---- using |:split| but having the same contents as window {nr}, and
---- then closing {nr}.
+--- Temporarily switch to window {target}, then move window {nr}
+--- to a new split adjacent to {target}.
+--- Unlike commands such as |:split|, no new windows are created
+--- (the |window-ID| of window {nr} is unchanged after the move).
 ---
 --- Both {nr} and {target} can be window numbers or |window-ID|s.
 --- Both must be in the current tab page.
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index b7120d5dd5..febd022254 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -12699,10 +12699,10 @@ M.funcs = {
     args = { 2, 3 },
     base = 1,
     desc = [=[
-      Move the window {nr} to a new split of the window {target}.
-      This is similar to moving to {target}, creating a new window
-      using |:split| but having the same contents as window {nr}, and
-      then closing {nr}.
+      Temporarily switch to window {target}, then move window {nr}
+      to a new split adjacent to {target}.
+      Unlike commands such as |:split|, no new windows are created
+      (the |window-ID| of window {nr} is unchanged after the move).
 
       Both {nr} and {target} can be window numbers or |window-ID|s.
       Both must be in the current tab page.
diff --git a/src/nvim/window.c b/src/nvim/window.c
index cfa28bbc1f..b1135d59fc 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -987,6 +987,8 @@ int win_split(int size, int flags)
 /// When "new_wp" is NULL: split the current window in two.
 /// When "new_wp" is not NULL: insert this window at the far
 /// top/left/right/bottom.
+/// On failure, if "new_wp" was not NULL, no changes will have been made to the
+/// window layout or sizes.
 /// @return  NULL for failure, or pointer to new window
 win_T *win_split_ins(int size, int flags, win_T *new_wp, int dir)
 {
@@ -1494,7 +1496,7 @@ win_T *win_split_ins(int size, int flags, win_T *new_wp, int dir)
 
   if (!(flags & WSP_NOENTER)) {
     // make the new window the current window
-    win_enter_ext(wp, WEE_TRIGGER_NEW_AUTOCMDS | WEE_TRIGGER_ENTER_AUTOCMDS
+    win_enter_ext(wp, (new_wp == NULL ? WEE_TRIGGER_NEW_AUTOCMDS : 0) | WEE_TRIGGER_ENTER_AUTOCMDS
                   | WEE_TRIGGER_LEAVE_AUTOCMDS);
   }
   if (vertical) {
diff --git a/test/old/testdir/test_window_cmd.vim b/test/old/testdir/test_window_cmd.vim
index 99a713d2ed..fc379c198d 100644
--- a/test/old/testdir/test_window_cmd.vim
+++ b/test/old/testdir/test_window_cmd.vim
@@ -1066,6 +1066,19 @@ func Test_win_splitmove()
   leftabove split b
   leftabove vsplit c
   leftabove split d
+
+  " win_splitmove doesn't actually create or close any windows, so expect an
+  " unchanged winid and no WinNew/WinClosed events, like :wincmd H/J/K/L.
+  let s:triggered = []
+  augroup WinSplitMove
+    au!
+    " Nvim: WinNewPre not ported yet. Also needs full port of v9.1.0117 to pass.
+    " au WinNewPre * let s:triggered += ['WinNewPre']
+    au WinNew * let s:triggered += ['WinNew', win_getid()]
+    au WinClosed * let s:triggered += ['WinClosed', str2nr(expand('<afile>'))]
+  augroup END
+  let winid = win_getid()
+
   call assert_equal(0, win_splitmove(winnr(), winnr('l')))
   call assert_equal(bufname(winbufnr(1)), 'c')
   call assert_equal(bufname(winbufnr(2)), 'd')
@@ -1088,6 +1101,11 @@ func Test_win_splitmove()
   call assert_equal(bufname(winbufnr(3)), 'a')
   call assert_equal(bufname(winbufnr(4)), 'd')
   call assert_fails('call win_splitmove(winnr(), winnr("k"), v:_null_dict)', 'E1297:')
+  call assert_equal([], s:triggered)
+  call assert_equal(winid, win_getid())
+
+  unlet! s:triggered
+  au! WinSplitMove
   only | bd
 
   call assert_fails('call win_splitmove(winnr(), 123)', 'E957:')