\newcommand is mixed

[impact27]

1- Create a file (test.tex) with:

\documentclass{article}
\usepackage[utf8]{inputenc}
\begin{document}

\newcommand{\be}{\begin{equation}}
\newcommand{\ee}{\end{equation}}

\end{document}

2- latexdiff test.tex test.tex > diff.tex

I get:

\documentclass{article}
%DIF LATEXDIFF DIFFERENCE FILE
%DIF DEL old.tex   Tue Jul 20 08:47:56 2021
%DIF ADD old.tex   Tue Jul 20 08:47:56 2021
\usepackage[utf8]{inputenc}
%DIF PREAMBLE EXTENSION ADDED BY LATEXDIFF
%DIF UNDERLINE PREAMBLE %DIF PREAMBLE
\RequirePackage[normalem]{ulem} %DIF PREAMBLE
\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1} %DIF PREAMBLE
\providecommand{\DIFadd}[1]{{\protect\color{blue}\uwave{#1}}} %DIF PREAMBLE
\providecommand{\DIFdel}[1]{{\protect\color{red}\sout{#1}}}                      %DIF PREAMBLE
%DIF SAFE PREAMBLE %DIF PREAMBLE
\providecommand{\DIFaddbegin}{} %DIF PREAMBLE
\providecommand{\DIFaddend}{} %DIF PREAMBLE
\providecommand{\DIFdelbegin}{} %DIF PREAMBLE
\providecommand{\DIFdelend}{} %DIF PREAMBLE
%DIF FLOATSAFE PREAMBLE %DIF PREAMBLE
\providecommand{\DIFaddFL}[1]{\DIFadd{#1}} %DIF PREAMBLE
\providecommand{\DIFdelFL}[1]{\DIFdel{#1}} %DIF PREAMBLE
\providecommand{\DIFaddbeginFL}{} %DIF PREAMBLE
\providecommand{\DIFaddendFL}{} %DIF PREAMBLE
\providecommand{\DIFdelbeginFL}{} %DIF PREAMBLE
\providecommand{\DIFdelendFL}{} %DIF PREAMBLE
%DIF END PREAMBLE EXTENSION ADDED BY LATEXDIFF

\begin{document}

\newcommand{\be}{\begin{equation}\end{equation}
\newcommand{\ee}{}}

\end{document}

Notice the \newcommand lines are mixed together.

This is LATEXDIFF 1.2.1  (Algorithm::Diff 1.15 so, Perl v5.30.0)
  (c) 2004-2017 F J Tilmann

[ftilmann]

You have discovered a way to fool latexdiff. In the current framework it's not that easy to fix. Can you move these definitions into the preamble? Alternatively, with --math-markup=3 it works. Thank you for your report, but the amount of effort to address this combined with it being quite an unusual setup, mean I will not address this in foreseeable future. As it's a bug I will leave the issue open, though (in case you are suprised to get a reaction so late. I was unable to allot much time to latexdiff in the last few months; I now try try to got through the backlog of issues and prioritise them)