fix(tui): reposition cursor after printing ambiguous-width character

src/nvim/tui/tui.c

@@ -875,6 +875,23 @@ static void cursor_goto(UI *ui, int row, int col)
   ugrid_goto(grid, row, col);
 }
 
+/// Move cursor to the position given by `row` and `col` and print `cell`.
+static void print_cell_at(UI* ui, int row, int col, UCell *cell)
+{
+  TUIData *data = ui->data;
+  UGrid *grid = &data->grid;
+  if (grid->row == -1 && cell->data[0] == NUL) {
+    // If cursor needs to repositioned and there is nothing to print, don't move cursor.
+    return;
+  }
+  cursor_goto(ui, row, col);
+  print_cell(ui, cell);
+  if (utf_ambiguous_width(utf_ptr2char(cell->data))) {
+    // Force repositioning cursor after printing an ambiguous-width character.
+    grid->row = -1;
+  }
+}
+
 static void clear_region(UI *ui, int top, int bot, int left, int right, int attr_id)
 {
   TUIData *data = ui->data;
@@ -1302,8 +1319,7 @@ static void tui_flush(UI *ui)
       }
 
       UGRID_FOREACH_CELL(grid, row, r.left, clear_col, {
-        cursor_goto(ui, row, curcol);
-        print_cell(ui, cell);
+        print_cell_at(ui, row, curcol, cell);
       });
       if (clear_col < r.right) {
         clear_region(ui, row, row + 1, clear_col, r.right, clear_attr);
@@ -1439,8 +1455,7 @@ static void tui_raw_line(UI *ui, Integer g, Integer linerow, Integer startcol, I
     grid->cells[linerow][c].attr = attrs[c - startcol];
   }
   UGRID_FOREACH_CELL(grid, (int)linerow, (int)startcol, (int)endcol, {
-    cursor_goto(ui, (int)linerow, curcol);
-    print_cell(ui, cell);
+    print_cell_at(ui, (int)linerow, curcol, cell);
   });
 
   if (clearcol > endcol) {
@@ -1458,8 +1473,8 @@ static void tui_raw_line(UI *ui, Integer g, Integer linerow, Integer startcol, I
     if (endcol != grid->width) {
       // Print the last char of the row, if we haven't already done so.
       int size = grid->cells[linerow][grid->width - 1].data[0] == NUL ? 2 : 1;
-      cursor_goto(ui, (int)linerow, grid->width - size);
-      print_cell(ui, &grid->cells[linerow][grid->width - size]);
+      print_cell_at(ui, (int)linerow, grid->width - size,
+                    &grid->cells[linerow][grid->width - size]);
     }
 
     // Wrap the cursor over to the next line. The next line will be