Environments with b-type argument cannot not be used in argument of array v2.6g 's >{...}

[AlexaraWu]

Brief outline of the bug

Environments with b-type argument cannot not be used in argument of array v2.6g 's >{...}.

Minimal example showing the bug

\RequirePackage{latexbug}
\documentclass{article}

% \usepackage{array}[=v2.5] % works
\usepackage{array} % don't work

\NewDocumentEnvironment{foo}{b}{\textit{#1}}{}

\newcolumntype{\bar}{>{\begin{foo}}c<{\end{foo}}}

\begin{document}

\begin{tabular}{\bar c}
  Hello & World \\
\end{tabular}

\end{document}

Log file (required) and possibly PDF file

mwe.log

[josephwright]

Cell collection is tricky - what's the motivation here of using a b spec rather than say collcell?

[josephwright]

My feeling here is that this usage is not supported, and we can address in the docs.