Pandoc Markdown parses too much LaTeX as a raw environment

[charmoniumQ]

Explain the problem.

$ cat test.md
\begin{tabular}{p{2in}}
\end{tabular}

# Test

\begin{tabular}{p{2\linewidth}}
\end{tabular}

$ pandoc test.md --to=native
[ RawBlock
    (Format "tex")
    "\\begin{tabular}{p{2in}}\n\\end{tabular}\n\n# Test\n\n\\begin{tabular}{p{2\\linewidth}}\n\\end{tabular}"
]

However, switching the order of the tabular environments, removing any of the tabular environments, or changing \linewidth to \textwidth causes the correct parse, which should be:

[ RawBlock
    (Format "tex") "\\begin{tabular}{p{2in}}\n\\end{tabular}"
, Header 1 ( "test" , [] , [] ) [ Str "Test" ]
, RawBlock
    (Format "tex")
    "\\begin{tabular}{p{2\\textwidth}}\n\\end{tabular}"
]

Pandoc version?

$ pandoc --version
pandoc 3.1.11
Features: +server +lua
Scripting engine: Lua 5.4
User data directory: /home/sam/.local/share/pandoc
Copyright (C) 2006-2023 John MacFarlane. Web: https://pandoc.org
This is free software; see the source for copying conditions. There is no
warranty, not even for merchantability or fitness for a particular purpose.

NixOS (if that matters)

Based on the description, I think this is distinct from this issue, because this issue is not about table elements.

[jgm]

I can reproduce this on the latest version too. It's quite bizarre!

[jgm]

Processing this with pandoc -f latex -t native just yields one table, not two, and the intermediate stuff is ignored. Similarly if you delete the #.

[jgm]

If you change the first 2in to 2\linewidth, it works, and if you change the second 2\linewidth to 2in, it works.

[jgm]

% pandoc -f latex -t native
\begin{tabular}{p{2in}}
\end{tabular}

Test

\begin{tabular}{p{2\linewidth}}
\end{tabular}
^D
[ Table
    ( "" , [] , [] )
    (Caption Nothing [])
    [ ( AlignLeft , ColWidthDefault ) ]
    (TableHead ( "" , [] , [] ) [])
    [ TableBody ( "" , [] , [] ) (RowHeadColumns 0) [] [] ]
    (TableFoot ( "" , [] , [] ) [])
]

[jgm]

Looking at the code, it seems that colwidth is currently set up only to handle cases like 2\linewidth, and not 2in. I'm not sure exactly how to handle 2in, because we don't have access to the linewidth in inches, but we could estimate I guess.

[jgm]

https://github.com/jgm/pandoc/blob/main/src/Text/Pandoc/Readers/LaTeX/Table.hs#L89-L95

[charmoniumQ]

When going from Markdown -> LaTeX, Should it not just pass through the \begin{...}...\end{...} as a raw block?

[jgm]

Yes, that's the desired end result. But the Markdown reader is deferring to the LaTeX reader to parse the raw environment. Something is going wrong there.

[jgm]

Also, as you can see above, this issue affects -f latex as well.