Titlesec and Babel incompatibility?

Question

I cannot find a way to change chapter style with babel included (for hungarian language). Here is the example:

\documentclass[a4paper]{report}
\usepackage[magyar]{babel}
\usepackage{titlesec}

\titleformat{\chapter}[hang]
{\normalfont}
{\LARGE\thechapter.}
{10pt}
{\LARGE\MakeUppercase}
[\normalfont]
\titlespacing{\chapter}{0pt}{0pt}{30pt}[0pt]

\begin{document}
\chapter{First chapter}
\end{document}

If I comment out the \usepackage[magyar]{babel} line, everything works as expected, however, with babel it does not work. Is it possible to style chapters (and sections, etc.) while using babel?

Answer 1

The magyar module for babel does a lot of stuff \AtBeginDocument; amongst other things (as egreg noticed in his comment), it restores the meaning of \chapter after \begin{document}, while not giving any method for overriding this choice. One possible workaround is to move the \titleformat and \titlespacing commands after \begin{document}:

\documentclass[a4paper]{report}
\usepackage[magyar]{babel}
\usepackage{titlesec}

\begin{document}

\titleformat{\chapter}[hang]
{\normalfont}
{\LARGE\thechapter.}
{10pt}
{\LARGE\MakeUppercase}
[\normalfont]
\titlespacing{\chapter}{0pt}{0pt}{30pt}[0pt]
\chapter{First chapter}

\end{document}

Answer 2

Actually I've found a way to solve this problem in package or class. Using \titleformat in \AtBeginDocument is useless, but the etoolbox has the \AfterEndPreamble{} macro which runs at the very end of the \begin{document}. Putting \titleformat into that makes titlesec work.