[tex-live] that nasty \undefined in supp-pdf.mkii again

[Joseph Wright]

On 24/10/2017 04:14, Norbert Preining wrote:
> Dear all,
> 
> back in 2010 (!!!) https://tug.org/pipermail/tex-live/2010-March/025102.html
> I complained about the fact that a minimal tex document
>   \documentclass{article}
>   \usepackage{graphicx}
>   \newcommand{\undefined}{\textbf{undefined}}
>   \begin{document}
>   This is an \undefined\ command.
>   \end{document}
> does not work anymore. This was due to the auto-loading of supp-pdf.mkii
> that was introduced in TL2009 (or so).
> 
> The reason is that supp-pdf.mkii uses
>   \ifx\writestatus\undefined
> to check for an undefined commands.
> 
> I argued that this is wrong to do it this way, especially since this
> is loaded now in LaTeX. See
> https://tug.org/pipermail/tex-live/2010-March/025107.html
> 
> There was the conclusion that pdftex.def should deal with this and
> Heiko send a fixed pftex.def:
> https://tug.org/pipermail/tex-live/2010-March/025126.html
> 
> I tested that and it worked.
> 
> But alas here we are in 2017 and a colleague just asked me the very same
> question, because he writes a logic text book and uses \undefined as
> a macro.
> 
> Can we somehow work that out again?
> 
> All the best
> 
> Norbert

I have to say I'm surprised anyone would use \undefined as a macro, but
I guess as it's a 'user' name (cf. LaTeX's \@ifundefined) then there's
always a chance.

Heiko's earlier mail doesn't say what fix he proposed, and the old FTP
site is no longer available. It seems most likely that the approach of
ensuring \undefined is really not defined is likely to be best,
something like altering the current

    \InputIfFileExists{supp-pdf.mkii}{}{}%

to

    \let\GPT at saved@undefined\undefined
    \let\undefined\GPT at undefined
    \InputIfFileExists{supp-pdf.mkii}{}{}%
    \let\undefined\GPT at saved@undefined

I guess will do it. I'll discuss with David C.

Joseph