DeclareMathOperator and digit in operator name

Vincent Lefevre <[email protected]>
Newsgroups gmane.comp.tex.live
Message-ID <[email protected]>
Hi,

After a recent upgrade of TeX Live in Debian/unstable
(2025.20251127 snapshot?), the following LaTeX file fails
to compile:

\documentclass{article}
\usepackage{amsopn}
\DeclareMathOperator{\Fast2Sum}{Fast2Sum}
\begin{document}
$\Fast2Sum(X)$
\end{document}

with an error on the \DeclareMathOperator.

This is due to the "2" in the operator name \Fast2Sum.

However, in

https://mirrors.ctan.org/install/macros/latex/required/latex-amsmath.tds.zip

I cannot see any corresponding change mentioned in "changes.txt".

So I'm wondering where this has changed in TeX Live and whether
this is a change done on purpose. In the latter case, where is
this change documented?

-- 
Vincent Lefèvre <[email protected]> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)
lmpx.com only provides a reader for public news (NNTP) servers. It is not affiliated with the servers or forums shown here and is not responsible for the content of articles, which is written by their respective authors.