%%
%% The LaTeX Companion, 3ed
%%
%% Example 11-4-35 on page II-177 in "amsmath, accents, mathdots --- Various accents".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{147.0pt}

  \setlength\parindent{0pt}

%StartShownPreambleCommands
\usepackage{accents}
%StopShownPreambleCommands

\begin{document}
$\mathbf{\hat{\accentset{\star}{\tilde h}}}$ (ok) but
$\mathcal{\hat{\accentset{\star}{\tilde X}}}$ (bad)
$\hat{\accentset{\star}{\tilde{\mathcal{X}}}}$ (ok again)
\end{document}
