vim-patch:9.1.1836: 'culopt' "screenline" not redrawn with line("w0") and :retab

Problem:  'cursorlineopt' "screenline" isn't redrawn when moving cursor
          and then using line("w0") and :retab that does nothing.
Solution: Call redraw_for_cursorcolumn() when setting a valid w_virtcol
          (zeertzjq).

closes: vim/vim#18506

a084914361
(cherry picked from commit ba47cb7eda)

src/nvim/cursor.c

@@ -64,8 +64,7 @@ int coladvance_force(colnr_T wcol)
     curwin->w_valid &= ~VALID_VIRTCOL;
   } else {
     // Virtcol is valid
-    curwin->w_valid |= VALID_VIRTCOL;
-    curwin->w_virtcol = wcol;
+    set_valid_virtcol(curwin, wcol);
   }
   return rc;
 }
@@ -85,8 +84,7 @@ int coladvance(win_T *wp, colnr_T wcol)
     wp->w_valid &= ~VALID_VIRTCOL;
   } else if (*(ml_get_buf(wp->w_buffer, wp->w_cursor.lnum) + wp->w_cursor.col) != TAB) {
     // Virtcol is valid when not on a TAB
-    wp->w_valid |= VALID_VIRTCOL;
-    wp->w_virtcol = wcol;
+    set_valid_virtcol(curwin, wcol);
   }
   return rc;
 }

src/nvim/move.c

@@ -181,6 +181,15 @@ static void redraw_for_cursorcolumn(win_T *wp)
   }
 }
 
+/// Set wp->w_virtcol to a value ("vcol") that is already valid.
+/// Handles redrawing if wp->w_virtcol was previously invalid.
+void set_valid_virtcol(win_T *wp, colnr_T vcol)
+{
+  wp->w_virtcol = vcol;
+  redraw_for_cursorcolumn(wp);
+  wp->w_valid |= VALID_VIRTCOL;
+}
+
 /// 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

src/nvim/window.c

@@ -6433,7 +6433,7 @@ void set_fraction(win_T *wp)
 /// calculate the new scroll position.
 /// TODO(vim): Ensure this also works with wrapped lines.
 /// Requires a not fully visible cursor line to be allowed at the bottom of
-/// a window("zb"), probably only when 'smoothscroll' is also set.
+/// a window ("zb"), probably only when 'smoothscroll' is also set.
 void win_fix_scroll(bool resize)
 {
   if (*p_spk == 'c') {