From 6fd7e3bea4c38e79c77fe506a45781ffd17ebe4f Mon Sep 17 00:00:00 2001
From: Luuk van Baal <luukvbaal@gmail.com>
Date: Fri, 28 Apr 2023 12:36:11 +0200
Subject: [PATCH] vim-patch:9.0.1000: with 'smoothscroll' skipcol may be reset
 unnecessarily

Problem:    With 'smoothscroll' skipcol may be reset unnecessarily.
Solution:   Check the line does actually fit in the window.

https://github.com/vim/vim/commit/b21b8e9ed081a6ef6b6745fe65d219b3ac046c3b

Co-authored-by: Bram Moolenaar <Bram@vim.org>
---
 src/nvim/move.c                            | 5 ++++-
 test/functional/legacy/scroll_opt_spec.lua | 9 +--------
 test/old/testdir/test_scroll_opt.vim       | 7 +++++++
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/nvim/move.c b/src/nvim/move.c
index 2bae811e6d..a6c87b641a 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -1465,7 +1465,10 @@ void adjust_skipcol(void)
   bool scrolled = false;
 
   validate_cheight();
-  if (curwin->w_cline_height == curwin->w_height) {
+  if (curwin->w_cline_height == curwin->w_height
+      // w_cline_height may be capped at w_height, check there aren't
+      // actually more lines.
+      && plines_win(curwin, curwin->w_cursor.lnum, false) <= curwin->w_height) {
     // the line just fits in the window, don't scroll
     reset_skipcol(curwin);
     return;
diff --git a/test/functional/legacy/scroll_opt_spec.lua b/test/functional/legacy/scroll_opt_spec.lua
index 6c8ca2cf97..31d851f571 100644
--- a/test/functional/legacy/scroll_opt_spec.lua
+++ b/test/functional/legacy/scroll_opt_spec.lua
@@ -494,14 +494,7 @@ describe('smoothscroll', function()
     ]])
     -- 'scrolloff' set to 2, scrolling down, cursor moves screen line up
     feed('<C-E>gj<C-Y>')
-    screen:expect([[
-      <<<ots of text with lots of text with lo|
-      ts of text with lots of text with lots o|
-      f text wi^th lots of text with lots of te|
-      xt with lots of text with lots of text w|
-      ith lots of text with lots of text with |
-                                              |
-    ]])
+    screen:expect_unchanged()
     -- 'scrolloff' set to 0, move cursor down one line. Cursor should move properly,
     -- and since this is a really long line, it will be put on top of the screen.
     exec('set scrolloff=0')
diff --git a/test/old/testdir/test_scroll_opt.vim b/test/old/testdir/test_scroll_opt.vim
index c8d0f51384..af46773ebf 100644
--- a/test/old/testdir/test_scroll_opt.vim
+++ b/test/old/testdir/test_scroll_opt.vim
@@ -498,6 +498,13 @@ func Test_smoothscroll_cursor_scrolloff()
   exe "normal 20h"
   call s:check_col_calc(1, 4, 61)
 
+  " cursor on last line, "gk" should not cause a scroll
+  set scrolloff=0
+  normal G0
+  call s:check_col_calc(1, 7, 1)
+  normal gk
+  call s:check_col_calc(1, 6, 101)
+
   bwipe!
 endfunc