Can not use upstream `TOC` struct creating hooks inside a figure or table environment (not an etoc issue)

[jfbu]

11

%% -*- mode: latex -*-
%% LaTeX2e file `etocsnippet-11.tex'
%% generated by the `filecontentshere' environment
%% from source `etoc' on 2024/01/12.
%% EDITED (\ref)
\begin{figure}[htbp!]\centering
\colorlet{subsecnum}{black}
\colorlet{secbackground}{green!30}
\colorlet{tocbackground}{red!20!green!20}

\renewcommand{\etocbkgcolorcmd}{\color{tocbackground}}
\renewcommand{\etocleftrulecolorcmd}{\color{tocbackground}}
\renewcommand{\etocrightrulecolorcmd}{\color{tocbackground}}
\renewcommand{\etocbottomrulecolorcmd}{\color{tocbackground}}
\renewcommand{\etoctoprulecolorcmd}{\color{tocbackground}}

\renewcommand{\etocleftrule}{\vrule width 3cm}
\renewcommand{\etocrightrule}{\vrule width 1cm}
\renewcommand{\etocbottomrule}{\hrule height 12pt}
\renewcommand{\etoctoprule}{\hrule height 12pt}

\renewcommand{\etocinnertopsep}{0pt}
\renewcommand{\etocinnerbottomsep}{0pt}
\renewcommand{\etocinnerleftsep}{0pt}
\renewcommand{\etocinnerrightsep}{0pt}

\newcommand\shiftedwhiterule[2]{%
    \hbox to \linewidth{\color{white}%
    \hskip#1\leaders\vrule height1pt\hfil}\nointerlineskip
    \vskip#2}

\etocsetlinestyle{subsubsection}
{\etocskipfirstprefix}
{\shiftedwhiterule{\leftskip}{6pt}}
{\sffamily\footnotesize
  \leftskip2.3cm\hangindent1cm\rightskip.5cm\relax
  \makebox[1cm][l]{\color{subsecnum}\etocnumber}%
  \color{black}\etocname
  \nobreak\leaders\hbox to.2cm{\hss.}\hfill
  \rlap{\makebox[.5cm][r]{\etocpage\hspace{.1cm}}}\par
  \nointerlineskip\vskip3pt}
{}

\etocsetlinestyle{subsection}
{\etocskipfirstprefix}
{\shiftedwhiterule{1.5cm}{6pt}}
{\sffamily\small
  \leftskip1.5cm\hangindent.8cm\rightskip.5cm\relax
  \makebox[.75cm][l]{\color{subsecnum}\etocnumber}%
  \color{black}\etocname
  \nobreak\leaders\hbox to.2cm{\hss.}\hfill
  \rlap{\makebox[.5cm][r]{\etocpage\hspace{.1cm}}}\par
  \nointerlineskip\vskip3pt}
{}

\newcommand{\coloredstuff}[2]{%
            \leftskip0pt\rightskip0pt\parskip0pt
            \fboxsep0pt % \colorbox uses \fboxsep also when no frame!
       \noindent\colorbox{secbackground}
               {\parbox{\linewidth}{%
                    \vskip5pt
                    {\noindent\color{#1}#2\par}\nointerlineskip
                    \vskip3pt}}%
       \par\nointerlineskip}

\etocsetlinestyle{section}
{\coloredstuff{blue}{\hfil \bfseries\large Contents of Part One\hfil}}
{\vskip3pt\sffamily\small}
{\coloredstuff{blue}
    {\leftskip1.5cm\rightskip.5cm\parfillskip-\rightskip
     \makebox[0pt][r]{\makebox[.5cm][l]{\etocnumber}}%
     \etocname\nobreak\hfill\makebox[.5cm][r]{\etocpage\hspace{.1cm}}}%
 \vskip6pt}
{}

\etocframedstyle[1]{}
\tableofcontents %%%%%%%%\label{toc:floating} \ref{toc:part:styling}
%%%%%%%%\vspace{-\baselineskip}
%%%%%%%%\centeredline{|\tableofcontents \ref{toc:part:styling}|
%%%%%%%%(\emph{cf.} \hyperref[toc:clone]{this other toc})}
\end{figure}
\endinput

[jfbu]

This is an artifact of presence of the figure environment. It is not clear if it is same upstream issue as latex3/tagging-project#55 (see #8), or more directly that one can put \tableofcontents (independently of etoc) in a figure environment, even in the form \@starttoc{toc} which does not have the title.

Fails even on first compilation with empty toc as the <TOC> struct is done then

\DocumentMetadata{
 uncompress,
 pdfversion=1.7,
 lang=en-US,
 testphase=phase-III
}
\documentclass{article}

\ExplSyntaxOn
 \msg_redirect_module:nnn { tag } { warning } { error }
\ExplSyntaxOff
\begin{document}

% \begin{figure}[htbp]
% %\section*{bar}% "The structure Sect can not be closed" (somewhat expected)
% \makeatletter
% \@starttoc{toc}% Parent-Child 'Note/' --> 'TOC/pdf'
% \end{figure}

\begin{table}[htbp]
\makeatletter
\@starttoc{toc}% Parent-Child 'Note/' --> 'TOC/pdf'
\end{table}

\section{foo}

\end{document}

I have tested removing the figure environment from the snippet code gives a passing test.