bug#42039: 27.0.91; (posn-x-y (posn-at-point)) inconsistent with display-line-numbers-mode

[Dmitry Gutov]

1. Enable display-line-numbers-mode.
2. Move point to the beginning of some line.
3. Evaluate (posn-x-y (posn-at-point))

=> The value in CAR will be > 0 (to account for the columns taken by 
d-l-n-m).

4. Do the same thing on a line that belongs to an overlay. For example,
the overlay in the bug reporting buffer (move point to the line with
"This bug report...").
5. The return value will be like (0 . 180).

The expected behavior: the column should still account for the offset by
the d-l-n-m.

I'd really like to see this fixed in Emacs, it makes positioning of
popups unpredictable when display-line-numbers-mode is enabled: 
https://github.com/company-mode/company-quickhelp/issues/106