subnode does not work well with xelatex

[jiaopjie]

When use the command \subnode to label some texts, some problem appears.
The following is the codes.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{tikzmark}
\begin{document}
\begin{tikzpicture}[remember picture,>=stealth]
\node{Assume \subnode{f}{$f'(x)$} exists};
\draw[->] (0,1) to (f);
\end{tikzpicture}
\end{document}

The target of f defined by \subnode will be wrong if compile with xelatex.
The result looks like the picture.

But, when compile using pdflatex or lualatex, the problem disappears.

I don't know whether the problem is due to tikzmark or xelatex itself.

[loopspace]

My understanding of this is that it is actually an issue with the xetex driver for pgf. There is an open issue on the pgf repository for this at pgf-tikz/pgf#353 and it was raised on TeX-SX some time ago at https://tex.stackexchange.com/q/229500/86.

Looking at the commits on the pgf repository, a fix was implemented but then reverted, so I imagine that the proposed fix had some issues elsewhere. Nevertheless, the suggestion there (which, I think, came from the TeX-SX thread) may work in specific cases so you could try it.