# how to prevent blur shadow nodes from writing a mysterious number in nullfont?

I've isolated a weird font-related issue that's coming from a blur shadow tikz node, which appears to be writing the value of some mystery counter in nullfont. The mystery counter starts at 17 and increments with each blur shadow node; non-blur shadow nodes do not seem to affect the mystery counter's value. There are some values that seem to equal 17 in my log file, but when I included enough blur shadow nodes to get the mystery counter up to 29, then my log file didn't contain 29 anywhere in it, so I don't have any surviving theory about what's happening or how to avoid it.

\documentclass{article}
\usepackage{tikz}

% I get the following warnings when I xelatex this document:
%    Missing character: There is no 1 ("31) in font nullfont!
%    Missing character: There is no 7 ("37) in font nullfont!
%    Missing character: There is no 1 ("31) in font nullfont!
%    Missing character: There is no 8 ("38) in font nullfont!
%    Missing character: There is no 1 ("31) in font nullfont!
%    Missing character: There is no 9 ("39) in font nullfont!
%
% Alternatively, if I uncomment the following line, I see a giant 17, 18, and 19 in the output.
%   \font\nullfont=cmr24

\begin{document}
\tikz{\node[draw, fill=white, blur shadow] {A};}  % Writes 17 [in nullfont]

\tikz{\node[draw, fill=white, blur shadow] {B};}  % Writes 18 [in nullfont]

\tikz{\node[draw, fill=white, blur shadow] {C};}  % Writes 19 [in nullfont]
\end{document}

• Welcome to TeX.SX and good catch! Dec 8 '21 at 2:49

It is a bug in pgfsys-dvipdfmx.def. They mixed up the \endcsname + \expandafter order:

\documentclass{article}
\usepackage{tikz}

\makeatletter
/S /Luminosity
>> >>}%<<
}
\makeatother

\begin{document}
\tikz{\node[draw, fill=white, blur shadow] {A};}  % Writes 17 [in nullfont]
%
\tikz{\node[draw, fill=white, blur shadow] {B};}  % Writes 18 [in nullfont]
%
\tikz{\node[draw, fill=white, blur shadow] {C};}  % Writes 19 [in nullfont]
\end{document}


I opened an issue https://github.com/pgf-tikz/pgf/issues/1088