Should /tikz/every cell style take two args instead of one?

[muzimuzhi]

Brief outline of the bug

Current implementation and usage

pgf/tex/generic/pgf/frontendlayer/tikz/tikz.code.tex

Line 1568 in 6e5fd71

\tikzset{every cell/.style= {}}%

pgf/tex/generic/pgf/frontendlayer/tikz/tikz.code.tex

Lines 3939 to 3941 in 6e5fd71

	matrix/inner style/every cell/.code={%
	\tikzset{every cell/.try={\the\pgfmatrixcurrentrow}{\the\pgfmatrixcurrentcolumn}}%
	},

Corresponding docs

pgf/doc/generic/pgf/pgfmanual-en-tikz-matrices.tex

Lines 376 to 385 in 6e5fd71

	\begin{stylekey}{/tikz/every cell=\marg{row}\marg{column} (initially \normalfont empty)}
	This style is installed at the beginning of each cell picture with the two
	parameters being the current \meta{row} and \meta{column} of the cell. Note
	that setting this style to |draw| will \emph{not} cause all nodes to be
	drawn since the |draw| option has to be passed to each node individually.
	Inside this style (and inside all cells), the current \meta{row} and
	\meta{column} number are also accessible via the counters
	|\pgfmatrixcurrentrow| and |\pgfmatrixcurrentcolumn|.
	\end{stylekey}

Minimal working example (MWE)

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix}

\begin{document}
% current
% \tikzset{every cell/.style={}}

\tikz[cells={execute at begin cell={\texttt{<rol-col #1>}}}]
  \matrix[matrix of nodes] { a & b \\ };

% proposed
\tikzset{every cell/.style 2 args={}}

\tikz[cells={execute at begin cell={\texttt{<row #1 col #2>}}}]
  \matrix[matrix of nodes] { a & b \\ };
\end{document}

[hmenke]

Looks like a reasonable change, but we should make sure that this doesn't break any package or existing document.

[muzimuzhi]

Smelled a sense of another breaking change for pgf 4.0.0 #869.

[hmenke]

Actually, it's not breaking at all, because right now the behavior is already broken since it contradicts the documentation. I think we can actually go ahead and fix it (like I did e.g. in 3.1.5 when I repaired intersection numbering).