From d95697d6d4533e84bbb9d262b355ee9f71bd7452 Mon Sep 17 00:00:00 2001
From: Luuk van Baal <luukvbaal@gmail.com>
Date: Wed, 26 Apr 2023 17:23:42 +0200
Subject: [PATCH] vim-patch:9.0.0673: first line wong with 'smoothscroll' and
 'scrolloff' zero

Problem:    First line not scrolled properly with 'smoothscroll' and
            'scrolloff' zero and using "k".
Solution:   Make sure the cursor position is visible.

https://github.com/vim/vim/commit/46b54747c5d252c584571a321231bad9330018ec

Co-authored-by: Bram Moolenaar <Bram@vim.org>
---
 src/nvim/move.c                            | 18 +++++++++++++++++-
 test/functional/legacy/scroll_opt_spec.lua | 15 ++++++++++++++-
 test/old/testdir/test_scroll_opt.vim       |  5 +++++
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/src/nvim/move.c b/src/nvim/move.c
index 0a91b12255..7c63aa9d7f 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -203,7 +203,7 @@ void update_topline(win_T *wp)
     bool check_topline = false;
     // If the cursor is above or near the top of the window, scroll the window
     // to show the line the cursor is in, with 'scrolloff' context.
-    if (wp->w_topline > 1) {
+    if (wp->w_topline > 1 || wp->w_skipcol > 0) {
       // If the cursor is above topline, scrolling is always needed.
       // If the cursor is far below topline and there is no folding,
       // scrolling down is never needed.
@@ -211,6 +211,15 @@ void update_topline(win_T *wp)
         check_topline = true;
       } else if (check_top_offset()) {
         check_topline = true;
+      } else if (wp->w_skipcol > 0 && wp->w_cursor.lnum == wp->w_topline) {
+        colnr_T vcol;
+
+        // check the cursor position is visible.  Add 3 for the ">>>"
+        // displayed in the top-left.
+        getvvcol(wp, &wp->w_cursor, &vcol, NULL, NULL);
+        if (wp->w_skipcol + 3 >= vcol) {
+          check_topline = true;
+        }
       }
     }
     // Check if there are more filler lines than allowed.
@@ -1499,6 +1508,7 @@ void scroll_cursor_top(int min_scroll, int always)
   linenr_T top;                 // just above displayed lines
   linenr_T bot;                 // just below displayed lines
   linenr_T old_topline = curwin->w_topline;
+  int old_skipcol = curwin->w_skipcol;
   linenr_T old_topfill = curwin->w_topfill;
   linenr_T new_topline;
   int off = (int)get_scrolloff_value(curwin);
@@ -1588,7 +1598,13 @@ void scroll_cursor_top(int min_scroll, int always)
       }
     }
     check_topfill(curwin, false);
+    // TODO(vim): if the line doesn't fit may optimize w_skipcol
+    if (curwin->w_topline == curwin->w_cursor.lnum) {
+      curwin->w_skipcol = 0;
+      redraw_later(curwin, UPD_NOT_VALID);
+    }
     if (curwin->w_topline != old_topline
+        || curwin->w_skipcol != old_skipcol
         || curwin->w_topfill != old_topfill) {
       curwin->w_valid &=
         ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
diff --git a/test/functional/legacy/scroll_opt_spec.lua b/test/functional/legacy/scroll_opt_spec.lua
index c63401cb02..fb4990ff00 100644
--- a/test/functional/legacy/scroll_opt_spec.lua
+++ b/test/functional/legacy/scroll_opt_spec.lua
@@ -307,7 +307,7 @@ describe('smoothscroll', function()
     screen:try_resize(40, 8)
     exec([[
       call setline(1, ['Line' .. (' with some text'->repeat(7))]->repeat(7))
-      set smoothscroll scrolloff=0
+      set smoothscroll scrolloff=0 display=
       :3
     ]])
     screen:expect([[
@@ -322,9 +322,22 @@ describe('smoothscroll', function()
     ]])
     feed('j')
     screen:expect_unchanged()
+    -- moving cursor down - whole bottom line shows
     feed('<C-E>j')
     screen:expect_unchanged()
     feed('G')
     screen:expect_unchanged()
+    -- moving cursor up - whole top line shows
+    feed('2k')
+    screen:expect([[
+      ^Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+      @                                       |
+                                              |
+    ]])
   end)
 end)
diff --git a/test/old/testdir/test_scroll_opt.vim b/test/old/testdir/test_scroll_opt.vim
index 799db19298..77e656cf9f 100644
--- a/test/old/testdir/test_scroll_opt.vim
+++ b/test/old/testdir/test_scroll_opt.vim
@@ -198,6 +198,7 @@ func Test_smoothscroll_wrap_scrolloff_zero()
 
   call VerifyScreenDump(buf, 'Test_smooth_wrap_1', {})
 
+  " moving cursor down - whole bottom line shows
   call term_sendkeys(buf, "j")
   call VerifyScreenDump(buf, 'Test_smooth_wrap_2', {})
 
@@ -207,6 +208,10 @@ func Test_smoothscroll_wrap_scrolloff_zero()
   call term_sendkeys(buf, "G")
   call VerifyScreenDump(buf, 'Test_smooth_wrap_4', {})
 
+  " moving cursor up - whole top line shows
+  call term_sendkeys(buf, "2k")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_5', {})
+
   call StopVimInTerminal(buf)
 endfunc