Re: Export of this table fails LuaLaTeX compilation

[gerard.vermeulen@posteo.net]

On 12.10.2022 07:55, Max Nikulin wrote:
> On 12/10/2022 12:15, gerard.vermeulen wrote:
>> On 12.10.2022 06:45, Max Nikulin wrote:
>>> 
>>> LuaLaTeX is irrelevant. It seems \hline is allowed only immediately
>>> after \\. Minimal LaTeX example:
>>> 
>>> \begin{tabular}{l}
>>> b\\\relax
>>> \hline
>>> \end{tabular}
>> 
>> Your example fails on my Mac texlive-2020 with:
>> 
>> ! Misplaced \noalign.
>> \hline ->\noalign
>>                    {\ifnum 0=`}\fi \hrule \@height \arrayrulewidth 
>> \futurelet...
>> 
>> l.40 \hline
>> 
>> It compiles when I remove \hline
> 
> Gerard, we forgot to post the reason why \relax has been added after
> \\. The intention was to  prevent errors in the case of
> 
> | a   |
> | [b] |
> 
> or
> 
> - item \\
>   [2022-10-12]
> 
> Stewart Thomas. [BUG] Tables with square brackets do not compile in
> PDF (latex) export. Wed, 10 Nov 2021 11:16:10 -0500.
> https://list.orgmode.org/CAO12V+wB18nAN0FuDPAeN94GHdt_2nbdJtc4u7n4W3HAZbaZsA@mail.gmail.com
> 
> I can not figure out an easy way to separate \\ from [b] text but to
> prevent the problem you have discovered. I am unsure if
> 
>     \\[0pt]
> 
> has no negative consequences and safe enough. I expect that LaTeX
> sources are not easy to read when fragile sequences of tokens are
> involved.
> 
> I just have realized that some users might take advantage of earlier
> behavior as a feature:
> 
> - item \\
>   [1cm]
> - item
> 
> I think that [1cm] should be treated as text, however I have no idea
> how to allow users to specify amount of vertical space and to not
> limit line break to LaTeX only. @@latex:\\[1cm]@@ is not suitable when
> the same text should be exported to ascii, html, etc.

Max, thanks for the background information.

For your info:
1. I also need to remove \relax in the LaTeX export using Gentoo 
texlive-2022 to compile.
2. On my systems ws-butler removes the trailing whitespace.
3. I edited your example with nano to add the trailing space after 
\relax, but it still does not compile.