Local options cannot be checked using the \ProcessKeyOptions command

[texno3]

Brief outline of the bug

Local options cannot be checked using the \ProcessKeyOptions command, In the previous LaTeX \aaa should have been bbb, but now it is aaa, indicating that option opt is not recognized by the macro package mypkg.

Minimal example showing the bug

\begin{filecontents}{mybook.cls}
\NeedsTeXFormat{LaTeX2e}
\ProvidesExplClass{mybook}{2024/12/21}{}{}
\DeclareKeys{opt.code = \def\aaa{aaa}}
\ProcessKeyOptions
\LoadClass{book}
\end{filecontents}

\begin{filecontents}{mypkg.sty}
\NeedsTeXFormat{LaTeX2e}
\ProvidesExplPackage{mypkg}{2024/12/21}{}{}
\DeclareKeys{opt.code = \def\aaa{bbb}}
\ProcessKeyOptions
\end{filecontents}

\documentclass[opt]{mybook}
\usepackage{mypkg}
 
\begin{document}
\aaa
\end{document}

[muzimuzhi]

This is the new expected behavior since LaTeX2e 2024-11-01.

To pass class options to packages, you need to use

\DeclareKeys{
  opt .code = \def\aaa{aaa},
  opt .pass-to-packages = true
}

The .pass-to-packages key property is added in the LaTeX2e 2024-11-01 release, and yes the default behavior has been changed since then.

texdoc clsguide (2024-09-15), sec. 4.4 "Creating and using keyval options" and texdoc ltnews40, sec. "Avoiding key–value option clashes between classes and packages" contain doc and motivation for this change.

[texno3]

Okay, thank you. I've noticed

This is the new expected behavior since LaTeX2e 2024-11-01.

To pass class options to packages, you need to use

\DeclareKeys{
  opt .code = \def\aaa{aaa},
  opt .pass-to-packages = true
}

The .pass-to-packages key property is added in the LaTeX2e 2024-11-01 release, and yes the default behavior has been changed since then.

texdoc clsguide (2024-09-15), sec. 4.4 Creating and using keyval options and texdoc ltnews40, sec. "Avoiding key–value option clashes between classes and packages" contain doc and motivation for this change.

Okay, thank you. I've noticed.

[FrankMittelbach]

As @muzimuzhi said, this was a deliberate change to avoid interaction problems that could otherwise occur.