Overfull hbox in patched use of algorithm2e environment

Question

I am using the algorithms environment from algorithm2e in a modified way with reduced width (following the solution here), see the MWE below.

This generates an overfull box that I'd like to get rid of. How can I achieve this?

\documentclass{article}
\usepackage{lipsum}
\usepackage{etoolbox}
\usepackage[ruled]{algorithm2e}
\SetCustomAlgoRuledWidth{0.6\textwidth}
\makeatletter
\patchcmd{\@algocf@start}{%
    \begin{lrbox}{\algocf@algobox}%
}{%
    \rule{0.2\textwidth}{\z@}%
    \begin{lrbox}{\algocf@algobox}%
    \begin{minipage}{0.6\textwidth}%
}{}{}
    \patchcmd{\@algocf@finish}{%
    \end{lrbox}%
}{%
    \end{minipage}%
    \end{lrbox}%
}{}{}
\makeatother
\begin{document}
    \lipsum[1]
    \begin{algorithm}[h]
        \caption{NaiveSelect}\label{algo:naive-option}
        Some alg step ;
    \end{algorithm}
    \lipsum[2]
\end{document}

The logfile says Overfull \hbox (276.00105pt too wide) in paragraph at lines 24--27.

Answer 1

You need to fix \algowidth.

\documentclass{article}
\usepackage{lipsum}
\usepackage{etoolbox}
\usepackage[ruled]{algorithm2e}
\AtBeginDocument{%
  \SetCustomAlgoRuledWidth{0.6\textwidth}%
  \setlength{\algowidth}{0.8\textwidth}%
}
\makeatletter
\patchcmd{@algocf@start}
  {\begin{lrbox}{\algocf@algobox}}
  {%
   \hspace*{0.2\textwidth}%
   \begin{lrbox}{\algocf@algobox}%
   \begin{minipage}{0.6\textwidth}%
  }
  {}{}
\patchcmd{@algocf@finish}
  {\end{lrbox}}
  {\end{minipage}\end{lrbox}}
  {}{}
\makeatother
\begin{document}
\lipsum[1]
\begin{algorithm}[h]
\caption{NaiveSelect}\label{algo:naive-option}
Some alg step ;
\end{algorithm}
\lipsum[2]
\end{document}

The value of \textwidth is known with certainty at begin document, so it's best to set parameters depending on it at that place.

Using \hspace*{0.2\textwidth} is simpler than a rule.