Rollback prior 2019/10/01 makes environment hooks noop

[mrpiggi]

As package etoolbox checks for the existence of \csname begin \endcsname and \csname end \endcsname in order to provide hooks with \AfterEndEnvironment etc. this fails for formats prior to 2019/10/01 as the robust macros are defined regardless of the format. It is questionable whether this is a problem of etoolbox or rather of latexrelease. For the latter case, I can open an issue at https://github.com/latex3/latex2e/issues if necessary.

\RequirePackage[2019/10/00]{latexrelease}
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{etoolbox}
\newenvironment{Foo}{}{}
\AfterEndEnvironment{Foo}{check!}
\begin{document}
\begin{Foo}
Foo
\end{Foo}

\csmeaning{end}

\csmeaning{end }
\end{document}

[josephwright]

I think the conclusion was to fix in the kernel ...

[mrpiggi]

Yep. It was discussed under https://github.com/latex3/latex2e/issues/494