vim-patch:9.0.1025: WinScrolled is not triggered when filler lines change (#21325)

Problem:    WinScrolled is not triggered when filler lines change.
Solution:   Add "topfill" to the values that WinScrolled triggers on.
            (closes vim/vim#11668)

https://github.com/vim/vim/commit/3fc84dc2c7efecd7c14ce341cd777475058936fd

Cherry-pick StopVimInTerminal() from patch 9.0.1010.

3 files changed, 86 insertions, 13 deletions

diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 8b01e23afd..3d3c6f0588 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -1193,6 +1193,7 @@ struct window_S {
 
   // five fields that are only used when there is a WinScrolled autocommand
   linenr_T w_last_topline;          ///< last known value for w_topline
+  linenr_T w_last_topfill;          ///< last known value for w_topfill
   colnr_T w_last_leftcol;           ///< last known value for w_leftcol
   colnr_T w_last_skipcol;           ///< last known value for w_skipcol
   int w_last_width;                 ///< last known value for w_width
diff --git a/src/nvim/testdir/test_autocmd.vim b/src/nvim/testdir/test_autocmd.vim
index 199721b15e..704ff6ec55 100644
--- a/src/nvim/testdir/test_autocmd.vim
+++ b/src/nvim/testdir/test_autocmd.vim
@@ -382,8 +382,8 @@ func Test_WinScrolled()
 
   let event = readfile('XscrollEvent')[0]->json_decode()
   call assert_equal({
-        \ 'all': {'leftcol': 1, 'topline': 0, 'width': 0, 'height': 0, 'skipcol': 0},
-        \ '1000': {'leftcol': -1, 'topline': 0, 'width': 0, 'height': 0, 'skipcol': 0}
+        \ 'all': {'leftcol': 1, 'topline': 0, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1000': {'leftcol': -1, 'topline': 0, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0}
         \ }, event)
 
   " Scroll up/down in Normal mode.
@@ -392,8 +392,8 @@ func Test_WinScrolled()
 
   let event = readfile('XscrollEvent')[0]->json_decode()
   call assert_equal({
-        \ 'all': {'leftcol': 0, 'topline': 1, 'width': 0, 'height': 0, 'skipcol': 0},
-        \ '1000': {'leftcol': 0, 'topline': -1, 'width': 0, 'height': 0, 'skipcol': 0}
+        \ 'all': {'leftcol': 0, 'topline': 1, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1000': {'leftcol': 0, 'topline': -1, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0}
         \ }, event)
 
   " Scroll up/down in Insert mode.
@@ -403,8 +403,8 @@ func Test_WinScrolled()
 
   let event = readfile('XscrollEvent')[0]->json_decode()
   call assert_equal({
-        \ 'all': {'leftcol': 0, 'topline': 1, 'width': 0, 'height': 0, 'skipcol': 0},
-        \ '1000': {'leftcol': 0, 'topline': -1, 'width': 0, 'height': 0, 'skipcol': 0}
+        \ 'all': {'leftcol': 0, 'topline': 1, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1000': {'leftcol': 0, 'topline': -1, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0}
         \ }, event)
 
   " Scroll the window horizontally to focus the last letter of the third line
@@ -416,8 +416,8 @@ func Test_WinScrolled()
 
   let event = readfile('XscrollEvent')[0]->json_decode()
   call assert_equal({
-        \ 'all': {'leftcol': 5, 'topline': 0, 'width': 0, 'height': 0, 'skipcol': 0},
-        \ '1000': {'leftcol': -5, 'topline': 0, 'width': 0, 'height': 0, 'skipcol': 0}
+        \ 'all': {'leftcol': 5, 'topline': 0, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1000': {'leftcol': -5, 'topline': 0, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0}
         \ }, event)
 
   " Ensure the command was triggered for the specified window ID.
@@ -567,6 +567,68 @@ func Test_WinScrolled_long_wrapped()
   call term_sendkeys(buf, '$')
   call term_sendkeys(buf, ":echo g:scrolled\<CR>")
   call WaitForAssert({-> assert_match('^3 ', term_getline(buf, 6))}, 1000)
+
+  call StopVimInTerminal(buf)
+endfunc
+
+func Test_WinScrolled_diff()
+  CheckRunVimInTerminal
+
+  let lines =<< trim END
+    set diffopt+=foldcolumn:0
+    call setline(1, ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'])
+    vnew
+    call setline(1, ['d', 'e', 'f', 'g', 'h', 'i'])
+    windo diffthis
+    func WriteScrollEvent()
+      call writefile([json_encode(v:event)], 'XscrollEvent')
+    endfunc
+    au WinScrolled * call WriteScrollEvent()
+  END
+  call writefile(lines, 'Xtest_winscrolled_diff', 'D')
+  let buf = RunVimInTerminal('-S Xtest_winscrolled_diff', {'rows': 8})
+
+  call term_sendkeys(buf, "\<C-E>")
+  call WaitForAssert({-> assert_match('^d', term_getline(buf, 3))}, 1000)
+
+  let event = readfile('XscrollEvent')[0]->json_decode()
+  call assert_equal({
+        \ 'all': {'leftcol': 0, 'topline': 1, 'topfill': 1, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1000': {'leftcol': 0, 'topline': 1, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1001': {'leftcol': 0, 'topline': 0, 'topfill': -1, 'width': 0, 'height': 0, 'skipcol': 0}
+        \ }, event)
+
+  call term_sendkeys(buf, "2\<C-E>")
+  call WaitForAssert({-> assert_match('^f', term_getline(buf, 3))}, 1000)
+
+  let event = readfile('XscrollEvent')[0]->json_decode()
+  call assert_equal({
+        \ 'all': {'leftcol': 0, 'topline': 2, 'topfill': 2, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1000': {'leftcol': 0, 'topline': 2, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1001': {'leftcol': 0, 'topline': 0, 'topfill': -2, 'width': 0, 'height': 0, 'skipcol': 0}
+        \ }, event)
+
+  call term_sendkeys(buf, "\<C-E>")
+  call WaitForAssert({-> assert_match('^g', term_getline(buf, 3))}, 1000)
+
+  let event = readfile('XscrollEvent')[0]->json_decode()
+  call assert_equal({
+        \ 'all': {'leftcol': 0, 'topline': 2, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1000': {'leftcol': 0, 'topline': 1, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1001': {'leftcol': 0, 'topline': 1, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0}
+        \ }, event)
+
+  call term_sendkeys(buf, "2\<C-Y>")
+  call WaitForAssert({-> assert_match('^e', term_getline(buf, 3))}, 1000)
+
+  let event = readfile('XscrollEvent')[0]->json_decode()
+  call assert_equal({
+        \ 'all': {'leftcol': 0, 'topline': 3, 'topfill': 1, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1000': {'leftcol': 0, 'topline': -2, 'topfill': 0, 'width': 0, 'height': 0, 'skipcol': 0},
+        \ '1001': {'leftcol': 0, 'topline': -1, 'topfill': 1, 'width': 0, 'height': 0, 'skipcol': 0}
+        \ }, event)
+
+  call StopVimInTerminal(buf)
 endfunc
 
 func Test_WinClosed()
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 1216bd8dcc..75320bcb7d 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -5306,6 +5306,7 @@ void snapshot_windows_scroll_size(void)
 {
   FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
     wp->w_last_topline = wp->w_topline;
+    wp->w_last_topfill = wp->w_topfill;
     wp->w_last_leftcol = wp->w_leftcol;
     wp->w_last_skipcol = wp->w_skipcol;
     wp->w_last_width = wp->w_width;
@@ -5327,7 +5328,8 @@ void may_make_initial_scroll_size_snapshot(void)
 /// window.
 /// Returns the dictionary with refcount set to one.
 /// Returns NULL on internal error.
-static dict_T *make_win_info_dict(int width, int height, int topline, int leftcol, int skipcol)
+static dict_T *make_win_info_dict(int width, int height, int topline, int topfill, int leftcol,
+                                  int skipcol)
 {
   dict_T *const d = tv_dict_alloc();
   d->dv_refcount = 1;
@@ -5351,6 +5353,10 @@ static dict_T *make_win_info_dict(int width, int height, int topline, int leftco
     if (tv_dict_add_tv(d, S_LEN("topline"), &tv) == FAIL) {
       break;
     }
+    tv.vval.v_number = topfill;
+    if (tv_dict_add_tv(d, S_LEN("topfill"), &tv) == FAIL) {
+      break;
+    }
     tv.vval.v_number = leftcol;
     if (tv_dict_add_tv(d, S_LEN("leftcol"), &tv) == FAIL) {
       break;
@@ -5394,6 +5400,7 @@ static int check_window_scroll_resize(int *size_count, win_T **first_scroll_win,
   int tot_width = 0;
   int tot_height = 0;
   int tot_topline = 0;
+  int tot_topfill = 0;
   int tot_leftcol = 0;
   int tot_skipcol = 0;
 
@@ -5426,6 +5433,7 @@ static int check_window_scroll_resize(int *size_count, win_T **first_scroll_win,
     }
 
     const bool scroll_changed = wp->w_last_topline != wp->w_topline
+                                || wp->w_last_topfill != wp->w_topfill
                                 || wp->w_last_leftcol != wp->w_leftcol
                                 || wp->w_last_skipcol != wp->w_skipcol;
     if (scroll_changed) {
@@ -5440,10 +5448,11 @@ static int check_window_scroll_resize(int *size_count, win_T **first_scroll_win,
       int width = wp->w_width - wp->w_last_width;
       int height = wp->w_height - wp->w_last_height;
       int topline = wp->w_topline - wp->w_last_topline;
+      int topfill = wp->w_topfill - wp->w_last_topfill;
       int leftcol = wp->w_leftcol - wp->w_last_leftcol;
       int skipcol = wp->w_skipcol - wp->w_last_skipcol;
-      dict_T *d = make_win_info_dict(width, height,
-                                     topline, leftcol, skipcol);
+      dict_T *d = make_win_info_dict(width, height, topline,
+                                     topfill, leftcol, skipcol);
       if (d == NULL) {
         break;
       }
@@ -5458,14 +5467,15 @@ static int check_window_scroll_resize(int *size_count, win_T **first_scroll_win,
       tot_width += abs(width);
       tot_height += abs(height);
       tot_topline += abs(topline);
+      tot_topfill += abs(topfill);
       tot_leftcol += abs(leftcol);
       tot_skipcol += abs(skipcol);
     }
   }
 
   if (v_event != NULL) {
-    dict_T *alldict = make_win_info_dict(tot_width, tot_height,
-                                         tot_topline, tot_leftcol, tot_skipcol);
+    dict_T *alldict = make_win_info_dict(tot_width, tot_height, tot_topline,
+                                         tot_topfill, tot_leftcol, tot_skipcol);
     if (alldict != NULL) {
       if (tv_dict_add_dict(v_event, S_LEN("all"), alldict) == FAIL) {
         tv_dict_unref(alldict);