Whole ToC line as link with titletoc

Question

Expected behavior:

• Whole ToC line becomes link to section

Observed behavior:

• xelatex - matches expected behavior
• pdflatex - breaks with "\pdfendlink cannot be used in vertical mode" error

Here is mwe:

\documentclass{article}

\usepackage{hyperref}
\usepackage{titletoc}

\makeatletter   
\titlecontents{section}[0cm]
    {\hyper@linkstart{link}{\Hy@tocdestname}}
    {\bfseries\thecontentslabel\hspace{1em}}
    {\bfseries}
    {\titlerule*[1pc]{.}\contentspage}
    [\hyper@linkend]
\makeatother

\begin{document}
     \tableofcontents

     \section{Test section}
\end{document}

After some googling found, that \protect is needed somewhere, cannot determine where.

Answer 1

After mindlessly trying different configurations, this is most sensible thing i came up with:

\documentclass{article}

\usepackage{hyperref}
\usepackage{titletoc}

\makeatletter   
\titlecontents{section}[0cm]
    {\hyper@linkstart{link}{\Hy@tocdestname}}
    {\bfseries\thecontentslabel\hspace{1em}}
    {\bfseries}
    {\titlerule*[1pc]{.}\thecontentspage\aftergroup\hyper@linkend}
\makeatother

\begin{document}
     \tableofcontents

     \section{Test section}
\end{document}

I do not understand why, but adding \aftergroup before link end and moving link end into same group as separator somehow works