luatexja-fontspec will yield some warnings
The reason is that luatexja does not define \slshape and \itshape for Japanese fonts as default.
Minimal example:
\documentclass{minimal}
\usepackage{luatexja}
\begin{document}
\itshape
\end{document}
Almost all Japanese (and Chinese?) fonts do not have italic shape. For example,
\documentclass{minimal}
\usepackage{fontspec}
\begin{document}
\fontspec{IPAMincho}\itshape
\end{document}
generates
LaTeX Font Warning: Font shape `EU2/IPAMincho(0)/m/it' undefined (Font) using `EU2/IPAMincho(0)/m/n' instead on input line 4.
On my linux box (with english locale and texlive 2014), the following code will generate warning.
\documentclass{article} \usepackage{luatexja-fontspec} \begin{document} \end{document}How can I suppress these warnings?