An hline input bug?

[Phelype Oleinik]

On Mon, Sep 20, 2021 at 9:02 AM Schneider, Thomas (NIH/NCI) [E]
<schneidt at mail.nih.gov> wrote:
>
> Phelype:
>
> > Try the solution given here:
> > https://tex.stackexchange.com/a/611803/134574
>
> Thanks!  The first solution using
>
> \CatchFileDef{\foo}{foo.tex}{}
>
> is pretty clean.  The second is rather ugly.

Actually the second solution:

    \ExplSyntaxOn
    \cs_new:Npn \expandableinput #1
      { \use:c { @@input } { \file_full_name:n {#1} } }
    \AddToHook{env/tabular/begin}
      { \cs_set_eq:NN \input \expandableinput }
    \ExplSyntaxOff

is cleaner as it has zero dependencies.  This is probably in line with
what may end up in LaTeX.

> This problem will continue to come up because people want to be able
> to make simple data tables and read them in.  So I'm wondering if
> there could be a way to change \input{} again so it handles this
> common situation cleanly.

This is a tricky issue, but it's already under the radar (see
https://github.com/latex3/latex2e/issues/514), and hopefully there will
be a good solution soonish.

Best,
Phelype