#261 `on grid' not working proberly for coordinates as reference

[Stefan Pinnow]

Hello developers,

it seems that on grid is not working as expected (by me) for coordinates.

Best regards,
Stefan Pinnow

% ----- minimal example -----
\documentclass{article}
\usepackage{tikz}
    \usetikzlibrary{
        positioning,
    }
\begin{document}
    \begin{tikzpicture}[
        font=\tiny,
        every node/.style={
            draw,
            rectangle,
            inner sep=0pt,
            outer sep=0pt,
            minimum size=5mm,
        },
    ]

        \draw[help lines] (-1,-1) grid (1,1);

        \node (a) at (0,0) {a};

        \node [on grid,above left=1 and 1 of a]             (b) {b};
        \node [on grid,above left=1 and 1 of a.north,red]   (c) {c};

        \draw           (a)         |- +(-1,1);
        \draw [red]     (a.north)   |- +(-1,1);     % `a.north' being a coordinate

        \node [minimum size=2.5mm,green]   (test) at (a.south) {};
        \node [on grid,below right=1 and 1 of test,green]   (d) {d};
        \draw [green]   (test)      |- +(1,-1);
    \end{tikzpicture}
\end{document}
% ---------------------------

[Till Tantau]

I agree that this is not the expected behaviour. Turns out one has to patch the core positioning code, which is tricky. I am postponing this.