vim-patch:9.0.1551: position of marker for 'smoothscroll' not computed correctly (#23617)

Problem:    Position of marker for 'smoothscroll' not computed correctly.
Solution:   Take 'list' and other options into account. (Luuk van Baal,
            closes vim/vim#12393)

https://github.com/vim/vim/commit/24b62ec8258cc7c9ca2c09f645f7f6b02584c892

2 files changed, 22 insertions, 16 deletions

diff --git a/src/nvim/change.c b/src/nvim/change.c
index a9e7126afc..f4969d0ca9 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -257,7 +257,8 @@ static void changed_common(linenr_T lnum, colnr_T col, linenr_T lnume, linenr_T
               || (wp->w_topline >= lnum
                   && wp->w_topline < lnume
                   && win_linetabsize(wp, wp->w_topline, ml_get(wp->w_topline), (colnr_T)MAXCOL)
-                  <= (unsigned)wp->w_skipcol + (wp->w_p_list && wp->w_p_lcs_chars.prec ? 1 : 3)))) {
+                  <= (unsigned)(wp->w_skipcol + sms_marker_overlap(wp, win_col_off(wp)
+                                                                   - win_col_off2(wp)))))) {
         wp->w_skipcol = 0;
       }
 
diff --git a/src/nvim/move.c b/src/nvim/move.c
index ada6d004e8..6a6f8149dd 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -164,19 +164,25 @@ static void redraw_for_cursorcolumn(win_T *wp)
   }
 }
 
-/// Calculates how much overlap the smoothscroll marker "<<<" overlaps with
-/// buffer text for curwin.
+/// Calculates how much the 'listchars' "precedes" or 'smoothscroll' "<<<"
+/// marker overlaps with buffer text for window "wp".
 /// Parameter "extra2" should be the padding on the 2nd line, not the first
 /// line.
 /// Returns the number of columns of overlap with buffer text, excluding the
 /// extra padding on the ledge.
-static int smoothscroll_marker_overlap(win_T *wp, int extra2)
+int sms_marker_overlap(win_T *wp, int extra2)
 {
-  // We don't draw the <<< marker when in showbreak mode, thus no need to
+  // There is no marker overlap when in showbreak mode, thus no need to
   // account for it.  See grid_put_linebuf().
   if (*get_showbreak_value(wp) != NUL) {
     return 0;
   }
+
+  // Overlap when 'list' and 'listchars' "precedes" are set is 1.
+  if (wp->w_p_list && wp->w_p_lcs_chars.prec) {
+    return 1;
+  }
+
   return extra2 > 3 ? 0 : 3 - extra2;
 }
 
@@ -270,12 +276,11 @@ void update_topline(win_T *wp)
       } else if (wp->w_skipcol > 0 && wp->w_cursor.lnum == wp->w_topline) {
         colnr_T vcol;
 
-        // Check that the cursor position is visible.  Add columns for the
-        // smoothscroll marker "<<<" displayed in the top-left if needed.
+        // Check that the cursor position is visible.  Add columns for
+        // the marker displayed in the top-left if needed.
         getvvcol(wp, &wp->w_cursor, &vcol, NULL, NULL);
-        int smoothscroll_overlap = smoothscroll_marker_overlap(wp,
-                                                               win_col_off(wp) - win_col_off2(wp));
-        if (wp->w_skipcol + smoothscroll_overlap > vcol) {
+        int overlap = sms_marker_overlap(wp, win_col_off(wp) - win_col_off2(wp));
+        if (wp->w_skipcol + overlap > vcol) {
           check_topline = true;
         }
       }
@@ -1426,10 +1431,9 @@ bool scrollup(long line_count, int byfold)
     long scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
     int space_cols = (curwin->w_height_inner - 1) * width2;
 
-    // If we have non-zero scrolloff, just ignore the <<< marker as we are
+    // If we have non-zero scrolloff, just ignore the marker as we are
     // going past it anyway.
-    int smoothscroll_overlap = scrolloff_cols != 0 ? 0 :
-                               smoothscroll_marker_overlap(curwin, extra2);
+    int overlap = scrolloff_cols != 0 ? 0 : sms_marker_overlap(curwin, extra2);
 
     // Make sure the cursor is in a visible part of the line, taking
     // 'scrolloff' into account, but using screen lines.
@@ -1438,13 +1442,13 @@ bool scrollup(long line_count, int byfold)
       scrolloff_cols = space_cols / 2;
     }
     validate_virtcol();
-    if (curwin->w_virtcol < curwin->w_skipcol + smoothscroll_overlap + scrolloff_cols) {
+    if (curwin->w_virtcol < curwin->w_skipcol + overlap + scrolloff_cols) {
       colnr_T col = curwin->w_virtcol;
 
       if (col < width1) {
         col += width1;
       }
-      while (col < curwin->w_skipcol + smoothscroll_overlap + scrolloff_cols) {
+      while (col < curwin->w_skipcol + overlap + scrolloff_cols) {
         col += width2;
       }
       curwin->w_curswant = col;
@@ -1489,8 +1493,9 @@ void adjust_skipcol(void)
   }
 
   validate_virtcol();
+  int overlap = sms_marker_overlap(curwin, curwin_col_off() - curwin_col_off2());
   while (curwin->w_skipcol > 0
-         && curwin->w_virtcol < curwin->w_skipcol + 3 + scrolloff_cols) {
+         && curwin->w_virtcol < curwin->w_skipcol + overlap + scrolloff_cols) {
     // scroll a screen line down
     if (curwin->w_skipcol >= width1 + width2) {
       curwin->w_skipcol -= width2;