patch 8.2.4797: getwininfo() may get oudated values

Problem:    getwininfo() may get oudated values.
Solution:   Make sure w_botline is up-to-date. (closes #10226)

src/evalwindow.c

@@ -395,6 +395,9 @@ get_win_info(win_T *wp, short tpnr, short winnr)
     if (dict == NULL)
 	return NULL;
 
+    // make sure w_botline is valid
+    validate_botline_win(wp);
+
     dict_add_number(dict, "tabnr", tpnr);
     dict_add_number(dict, "winnr", winnr);
     dict_add_number(dict, "winid", wp->w_id);

src/testdir/test_bufwintabinfo.vim

@@ -172,4 +172,26 @@ func Test_getbufinfo_lines()
   bw!
 endfunc
 
+func Test_getwininfo_au()
+  enew
+  call setline(1, range(1, 16))
+
+  let g:info = #{}
+  augroup T1
+    au!
+    au WinEnter * let g:info = getwininfo(win_getid())[0]
+  augroup END
+
+  4split
+  " Check that calling getwininfo() from WinEnter returns fresh values for
+  " topline and botline.
+  call assert_equal(1, g:info.topline)
+  call assert_equal(4, g:info.botline)
+  close
+
+  unlet g:info
+  augroup! T1
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4797,
 /**/
     4796,
 /**/