vim-patch:9.0.0915: WinScrolled may trigger immediately when defined

Problem:    WinScrolled may trigger immediately when defined.
Solution:   Initialize the fields in all windows. (closes vim/vim#11582)

https://github.com/vim/vim/commit/29967732761d1ffb5592db5f5aa7036f5b52abf1

Co-authored-by: Bram Moolenaar <Bram@vim.org>

1 files changed, 24 insertions, 9 deletions

diff --git a/src/nvim/window.c b/src/nvim/window.c
index 4a451975a4..f25e25e905 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -3868,6 +3868,27 @@ void close_others(int message, int forceit)
   }
 }
 
+/// Store the relevant window pointers for tab page "tp".  To be used before
+/// use_tabpage().
+void unuse_tabpage(tabpage_T *tp)
+{
+  tp->tp_topframe = topframe;
+  tp->tp_firstwin = firstwin;
+  tp->tp_lastwin = lastwin;
+  tp->tp_curwin = curwin;
+}
+
+/// Set the relevant pointers to use tab page "tp".  May want to call
+/// unuse_tabpage() first.
+void use_tabpage(tabpage_T *tp)
+{
+  curtab = tp;
+  topframe = curtab->tp_topframe;
+  firstwin = curtab->tp_firstwin;
+  lastwin = curtab->tp_lastwin;
+  curwin = curtab->tp_curwin;
+}
+
 // Allocate the first window and put an empty buffer in it.
 // Only called from main().
 void win_alloc_first(void)
@@ -3878,11 +3899,8 @@ void win_alloc_first(void)
   }
 
   first_tabpage = alloc_tabpage();
-  first_tabpage->tp_topframe = topframe;
   curtab = first_tabpage;
-  curtab->tp_firstwin = firstwin;
-  curtab->tp_lastwin = lastwin;
-  curtab->tp_curwin = curwin;
+  unuse_tabpage(first_tabpage);
 }
 
 // Init `aucmd_win`. This can only be done after the first window
@@ -4253,10 +4271,7 @@ static void enter_tabpage(tabpage_T *tp, buf_T *old_curbuf, bool trigger_enter_a
   win_T *next_prevwin = tp->tp_prevwin;
   tabpage_T *old_curtab = curtab;
 
-  curtab = tp;
-  firstwin = tp->tp_firstwin;
-  lastwin = tp->tp_lastwin;
-  topframe = tp->tp_topframe;
+  use_tabpage(tp);
 
   if (old_curtab != curtab) {
     tabpage_check_windows(old_curtab);
@@ -5265,7 +5280,7 @@ void win_new_screen_cols(void)
 
 /// Make a snapshot of all the window scroll positions and sizes of the current
 /// tab page.
-static void snapshot_windows_scroll_size(void)
+void snapshot_windows_scroll_size(void)
 {
   FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
     wp->w_last_topline = wp->w_topline;