Lineno breaks/hides content, if \nointerlineskip is used.

[T-F-S]

In T-F-S/tcolorbox#183 a problem in interaction between tcolorbox and lineno was reported.

The problem is nailed down to a \prevdepth problem with lineno in T-F-S/tcolorbox#183 (comment):

\documentclass{article}
\usepackage{lineno}

\linenumbers

\begin{document}
before text

% excerpted from `before skip balanced`
\par\nointerlineskip
% excerpted from \tcb@prepare@break@operation
\noindent% applies parskip
\vskip\lineskip
content

after text
\end{document}

Also, an incomplete patch for lineno is provided in T-F-S/tcolorbox#183 (comment)

[kwwette]

@T-F-S Thanks for reporting this. I don't understand the lineno code well enough to know how to fix this, but I'd be happy to accept a complete patch if you have one.

[kwwette]

Closing this issue as I believe this has been resolved by T-F-S/tcolorbox#183; if that's not correct please let me know.

[muzimuzhi]

This is issue is reproducible without tcolorbox. It's really about handling a special value of \prevdepth (-1000pt) set by \nointerlineskip.

Default	Using \linenumbers	My attempt T-F-S/tcolorbox#183 (comment)	Frank's patch T-F-S/tcolorbox#183 (comment)

Full example

\documentclass{article}
\usepackage{lineno}
\usepackage{multicol}

\makeatletter
\def\muzimuzhiPATCH{%
  \def\@LN@depthbox{% 
    % \@tempdima is set to \prevdepth before
    \ifdim\@tempdima>-1000pt\relax
      \dp\@tempboxa=\@tempdima
    \fi
    \nointerlineskip
    \ifdim\@tempdima>-1000pt\relax
      \kern-\@tempdima
    % \else % is this needed?
    %   \kern-\dp\@tempboxa
    \fi
    \box\@tempboxa}}

\def\FrankPATCH{%
  \def\@LN@depthbox{%
    \ifdim\@tempdima = -1000pt
    % \nointerlineskip is already set so we don't need set it again (and we shouldn't back up)
    \else
      \dp\@tempboxa=\@tempdima
      \nointerlineskip
      \kern-\@tempdima 
    \fi
    \box\@tempboxa}}
\makeatother


\begin{document}

\def\testWithPrevdepth#1{{%
  \noindent\texttt{\UseName{str_if_empty:nTF}{#1}{default}{\detokenize{#1}}}\par
  before text\par
  #1%
  \noindent\vskip0pt % any vskip triggers the problem
  content\par
  after text\par}\medskip}

\def\tests#1{{#1%
  \testWithPrevdepth{}
  \testWithPrevdepth{\prevdepth=10pt}
  \testWithPrevdepth{\prevdepth=-10pt}
  \testWithPrevdepth{\prevdepth=-100pt}
  \testWithPrevdepth{\prevdepth=-1000pt}
  \newpage
}}

\tests{}
\tests{\linenumbers}
\tests{\linenumbers\muzimuzhiPATCH}
\tests{\linenumbers\FrankPATCH}

\end{document}

[kwwette]

Thanks @muzimuzhi for the examples. I've applied Frank's patch to lineno.sty. Could you please confirm that this version of lineno.sty fixes the issue and behaves as you expect?

[muzimuzhi]

Just one concern: the inter-line skip is actually altered by \linenumbers. Is this OK?

If that's OK, then here's a similar patch for \internallinenumberpar (used by user command \internallinenumbers) and bframe env:

diff --git a/lineno.sty b/lineno.sty
index 9fb0be8..1107b4c 100644
--- a/lineno.sty
+++ b/lineno.sty
@@ -2725,10 +2725,14 @@ Macro file lineno.sty for LaTeX: attach line numbers, refer to them.
      \begingroup
         \c@internallinenumbers\prevgraf
         \setbox\@tempboxa\hbox{\vbox{\makeinternalLinenumbers}}%
-        \dp\@tempboxa\prevdepth
         \ht\@tempboxa\z@
-        \nobreak\vskip-\prevdepth
-        \nointerlineskip\box\@tempboxa
+        \ifdim\prevdepth=-1000pt
+        \else
+          \dp\@tempboxa\prevdepth
+          \nobreak\vskip-\prevdepth
+          \nointerlineskip
+        \fi
+        \box\@tempboxa
      \endgroup
      \fi\fi
      }
@@ -2866,7 +2870,9 @@ Macro file lineno.sty for LaTeX: attach line numbers, refer to them.
    \def\makeLineNumber{\copy\bframebox\hss}%
   }
   {\par
-   \kern-\prevdepth
+   \ifdim\prevdepth=-1000pt \else
+     \kern-\prevdepth
+   \fi
    \kern\bframesep
    \nointerlineskip
    \@tempdima\textwidth

Default	Using \linenumbers + Frank's patch extended
On next column/page On third column/page

Full example, v2

\documentclass[twocolumn]{article}
\usepackage{lineno}

\makeatletter
\def\FrankPATCH{%
  \def\@LN@depthbox{%
    \ifdim\@tempdima=-1000pt
    % \nointerlineskip is already set so we don't need set it again (and we shouldn't back up)
    \else
      \dp\@tempboxa=\@tempdima
      \nointerlineskip
      \kern-\@tempdima
    \fi
    \box\@tempboxa}%
  \renewcommand\internallinenumberpar{%
    \ifvmode\@@@par\else\ifinner\@@@par\else\@@@par
    \begingroup
    \c@internallinenumbers\prevgraf
    \setbox\@tempboxa\hbox{\vbox{\makeinternalLinenumbers}}%
    \ht\@tempboxa\z@
    \ifdim\prevdepth=-1000pt
    \else
      \dp\@tempboxa\prevdepth
      \nobreak\vskip-\prevdepth
      \nointerlineskip
    \fi
    \box\@tempboxa
    \endgroup
    \fi\fi
  }
  \renewcommand\endbframe{%
    \par
    \ifdim\prevdepth=-1000pt \else
      \kern-\prevdepth
    \fi
    \kern\bframesep
    \nointerlineskip
    % \textwidth is proposed to be replaced with \columnwidth in
    %   https://github.com/latex-lineno/lineno/pull/8
    \@tempdima\textwidth
    \advance\@tempdima 2\bframesep
    \hbox{\hskip-\bframesep
         \vrule\@width\@tempdima\@height\bframerule\@depth\z@}%
  }
}
\makeatother

% just tweak
% see full fix in https://github.com/latex-lineno/lineno/pull/8
\AtBeginDocument{%
  \textwidth=\dimexpr\columnwidth-10pt
}

\raggedbottom

\begin{document}

\def\testWithPrevdepth#1{{%
  \noindent\texttt{\UseName{str_if_empty:nTF}{#1}{default}{\detokenize{#1}}}\par

  before text\par
  #1%
  \noindent\vskip0pt % any vskip triggers the problem
  content\par
  after text\par}}

\def\tests#1{{#1%
  \testWithPrevdepth{}
%  \testWithPrevdepth{\prevdepth=10pt}
  \testWithPrevdepth{\prevdepth=-10pt}
%  \testWithPrevdepth{\prevdepth=-100pt}
  \testWithPrevdepth{\prevdepth=-1000pt}
  \begin{center}
    \UseName{tl_if_in:nnT}{#1}{\linenumbers}{\internallinenumbers}%
    \testWithPrevdepth{}
  \end{center}
  \begin{center}
    \UseName{tl_if_in:nnT}{#1}{\linenumbers}{\internallinenumbers}%
    \testWithPrevdepth{\prevdepth=-10pt}
  \end{center}
  \begin{center}
    \UseName{tl_if_in:nnT}{#1}{\linenumbers}{\internallinenumbers}%
    \testWithPrevdepth{\prevdepth=-1000pt}
  \end{center}
  \begin{bframe}
    foo\par
    \nointerlineskip
  \end{bframe}
  \begin{bframe}
    \testWithPrevdepth{\prevdepth=-1000pt}
  \end{bframe}
  \newpage
}}

\tests{\linenumbers\FrankPATCH}
\tests{}

\end{document}

[kwwette]

Thanks again @muzimuzhi I've applied the additional patches. Can you please check the latest version of lineno.sty is working correctly?

I couldn't work out how to remove the extra inter-line skip. It's probably fine as is, so I may leave it for now.

[kwwette]

I've submitted a new release of linono (v5.3) to CTAN with these changes.

[muzimuzhi]

Ignoring the restored inter-line skip, I can confirm lineno v5.3 works correctly. Thank you for this update and sorry for my late response.