The command \'
becomes \EU1-cmd\' \EU1\'
and then \EU1-cmd
checks if the combination
\\EU1\'-.
is defined; the control sequence has \EU1\'-.
as name and can be checked by
\expandafter\show\csname\string\EU1\string\'-.\endcsname
which gives
> \\EU1\'-.=macro:
->\TIPAaccent {\textdotacute }.
Now the problem follows, because \TIPAaccent
wants two arguments, and it finds \end
which is surely not a good token for it.
Here's an example:
\documentclass{article}
\usepackage{fontspec}
\setmainfont{Gentium}
\begin{document}
\'.e
\end{document}
Gentium is needed because Latin Modern doesn't have the required glyph.
In conclusion, \TeX\'.
shows a bad usage of the backslash after \TeX
.
If you need \'.
for demonstration purposes, you can undeclare the composite using the command I suggested in https://tex.stackexchange.com/a/58115/4427
\documentclass{article}
\usepackage{fontspec}
\setmainfont{CMU Serif}
\providecommand*\UndeclareTextComposite[3]{%
\expandafter\let\csname\expandafter\string\csname
#2\endcsname\string#1-#3\endcsname\relax}
\UndeclareTextComposite{\'}{EU1}{.}
\begin{document}
`\TeX\'.
\end{document}
The placement of the accent isn't the same as with cmr10
; this depends on the fonts.
\'
is not a valid control sequence there.\TeX\'. \vfill\eject\bye
and compile it usingpdftex
(notpdflatex
).fontspec
and runpdflatex
and see the result yourself.fontspec
has some kind of failsafe, as it won't put together characters but uses the unicode ones provided by the font.