Spot color not recognized in tikz

[jbezos]

Here is a mwe:

\documentclass{article}
 
\usepackage{colorspace}
\usepackage{tikz}
\usetikzlibrary{calc}
 
\definespotcolor{registration}{All}{1,1,1,1}
 
\pagestyle{empty}
\begin{document}
 
    \tikz \draw [draw=registration] (0.0,0.0) rectangle (0.5,0.5); % not shown
    \tikz \draw [draw=black] (0.0,0.0) rectangle (0.5,0.5);
 
\end{document}

See https://tex.stackexchange.com/questions/471575/how-can-i-create-a-color-registration-test-page-with-latex/471576#471576

[u-fischer]

For a reason that I don't understand (and imho is rather odd) tikz uses sometimes \colorlet[named]{...}{...} to copy colors, and that breaks with colorspace as it then tries to recalculate the color from the last two arguments, and that fails with colorspace where this argument contains {&spot}{1}. If one redefine the colorlet command it works again:

\documentclass{article}
\pagestyle{empty}

\usepackage{tikz}  
\usepackage{colorspace}

\makeatletter
\def\pgfutil@colorlet#1#2{\colorlet{#1}{#2}}
\makeatother

\usetikzlibrary{calc}

\definespotcolor{registration}{All}{1,1,1,1}

\pagestyle{empty}
\begin{document}

    \tikz \draw [draw=registration] (0.0,0.0) rectangle (0.5,0.5); % not shown
    \tikz \draw [draw=black] (0.0,0.0) rectangle (0.5,0.5);

\end{document}