[Bug] \UseTblrLibrary{tikz} and in-cell \color{} do not like each other

[mariuslp]

Tell us about the system on which the bug was produced

• Distribution and year (e.g., TeXLive 2025): TexLive2025
• Engine used (e.g., LuaLaTeX): pdflatex and lualatex (works correctly with Xelatex)
• Operating system (e.g., Gentoo Linux): Whatever overleaf uses

Please outline the bug as you have found it

This is the weirdest bug I have found so far.

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{tikz}  % required for the bug to happen
\usepackage{xcolor}

\begin{document}
\begin{tblr}{
  colspec={llll},
}
a & b & c & d \\ \hline
1 & {\color{red} 2} & 3 & 4 \\
\end{tblr}

\end{document}

Will create an absurdly long second cell, and with broken alignment.

I get two warnings:

Package varwidth Warning: Failed to reprocess entire contents on input line 13. LaTeX Font Info: External font cmex10' loaded for size (Font) <7> on input line 13. LaTeX Font Info: External font cmex10' loaded for size (Font) <5> on input line 13.

and

Package varwidth Warning: Failed to reprocess entire contents on input line 13.

The bug disappears if we don't use the library tikz.

Obviously, the best way to change text color is with the fg cell command, so this is not a high priority bug.

[quark67]

Bug (?) confirmed on TeX Live 2026, macOS 26, pdfLaTeX or LuaLaTeX.

But it works if you add \UseTblrLibrary{varwidth} and measure=vbox in the options of the tblr environment:

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{tikz}  % required for the bug to happen
\UseTblrLibrary{varwidth}
\usepackage{xcolor}

\begin{document}
\begin{tblr}{
  colspec={llll},measure=vbox
}
a & b & c & d \\ \hline
1 & {\color{red} 2} & 3 & 4 \\
\end{tblr}

\end{document}

I don't know why this works when we add this (see 5.11 Library varwidth on page 57 of the manual).

[jasperhabicht]

This issue is related to the hook library which the tikz library loads per default.

As far as I remember (it's been a while that I worked on the code for the tikz library), the tikz library does not add any code in the cells, it only appends stuff before or after the table. So it should not interfere with the contents of the cell at all. But probably some inserted hook does.

If you load the hook library instead of the tikz library in your above MWE, you'll get the same issue.