vim-patch:9.0.0758: "precedes" from 'listchars' overwritten by <<<

Problem:    "precedes" from 'listchars' overwritten by <<< for 'smoothscroll'.
Solution:   Keep the "precedes" character.

https://github.com/vim/vim/commit/13cdde39520220bb856cba16626327c706752b51

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

3 files changed, 63 insertions, 3 deletions

diff --git a/src/nvim/grid.c b/src/nvim/grid.c
index 8431c078b9..9e830413bd 100644
--- a/src/nvim/grid.c
+++ b/src/nvim/grid.c
@@ -530,9 +530,12 @@ void grid_put_linebuf(ScreenGrid *grid, int row, int coloff, int endcol, int cle
   max_off_from = linebuf_size;
   max_off_to = grid->line_offset[row] + (size_t)grid->cols;
 
-  if (topline && wp->w_skipcol > 0 && *get_showbreak_value(wp) == NUL) {
-    // Take care of putting "<<<" on the first line for 'smoothscroll'
-    // when 'showbreak' is not set.
+  // Take care of putting "<<<" on the first line for 'smoothscroll'.
+  if (topline && wp->w_skipcol > 0
+      // do not overwrite the 'showbreak' text with "<<<"
+      && *get_showbreak_value(wp) == NUL
+      // do not overwrite the 'listchars' "precedes" text with "<<<"
+      && !(wp->w_p_list && wp->w_p_lcs_chars.prec != 0)) {
     int off = 0;
     int skip = 0;
     if (wp->w_p_nu && wp->w_p_rnu) {
diff --git a/test/functional/legacy/scroll_opt_spec.lua b/test/functional/legacy/scroll_opt_spec.lua
index 5e54470bd4..b5a571d8b5 100644
--- a/test/functional/legacy/scroll_opt_spec.lua
+++ b/test/functional/legacy/scroll_opt_spec.lua
@@ -294,6 +294,38 @@ describe('smoothscroll', function()
     ]])
   end)
 
+  -- oldtest: Test_smoothscroll_list()
+  it("works with list mode", function()
+    screen:try_resize(40, 8)
+    exec([[
+      set smoothscroll scrolloff=0
+      set list
+      call setline(1, [ 'one', 'very long text '->repeat(12), 'three', ])
+      exe "normal 2Gzt\<C-E>"
+    ]])
+    screen:expect([[
+      <<<t very long text very long text very |
+      ^long text very long text very long text |
+      very long text very long text very long |
+      text very long text-                    |
+      three                                   |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    exec('set listchars+=precedes:#')
+    screen:expect([[
+      #ext very long text very long text very |
+      ^long text very long text very long text |
+      very long text very long text very long |
+      text very long text-                    |
+      three                                   |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+  end)
+
   -- oldtest: Test_smoothscroll_diff_mode()
   it("works with diff mode", function()
     screen:try_resize(40, 8)
diff --git a/test/old/testdir/test_scroll_opt.vim b/test/old/testdir/test_scroll_opt.vim
index c394c6adf8..423cba76bf 100644
--- a/test/old/testdir/test_scroll_opt.vim
+++ b/test/old/testdir/test_scroll_opt.vim
@@ -172,6 +172,31 @@ func Test_smoothscroll_number()
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_smoothscroll_list()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      set smoothscroll scrolloff=0
+      set list
+      setline(1, [
+        'one',
+        'very long text '->repeat(12),
+        'three',
+      ])
+      exe "normal 2Gzt\<C-E>"
+  END
+  call writefile(lines, 'XSmoothList', 'D')
+  let buf = RunVimInTerminal('-S XSmoothList', #{rows: 8, cols: 40})
+
+  call VerifyScreenDump(buf, 'Test_smooth_list_1', {})
+
+  call term_sendkeys(buf, ":set listchars+=precedes:#\<CR>")
+  call VerifyScreenDump(buf, 'Test_smooth_list_2', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
 func Test_smoothscroll_diff_mode()
   CheckScreendump