#409 user error leading to unexpected loop

[David Carlisle]

this arises from a user question at

http://tex.stackexchange.com/questions/338869/pdflatex-hangs-on-a-pending

after

\documentclass{article}
\usepackage{tikz}
\makeatletter
\protected\def\tikz@signal@path{\tikz@signal@path}%
\makeatother
\begin{document}
  \begin{tikzpicture}[
    \draw[blue] (0,0) -- (1,1);
  \end{tikzpicture}
\end{document}

tex loops exanding \tikz@signal@path forever.

\def\tikz@signal@path{\tikz@signal@path}
\tikz@signal@path

In the answer I suggested an etex \protected def but I wasn't totally sure why the test is using the recursive definition, here it seems:

\def\tikz@lib@matrix@check#1{% evil hackery to find out about start of path

so \protected may be wrong or there are of course non e-tex alternatives

David

[Stefan Pinnow]

See https://github.com/pgf-tikz/pgf/issues/408