microtype `testls` command does not work

[cgahr]

The textls command of the microtype package does not work.

Consider the following document:

% test.tex
\documentclass[12pt, a4paper]{article}

\usepackage{microtype}

\begin{document}
\textls[100]{this should work}
\end{document}

$ pdflatex test.tex$:

$ tectonic test.tex -Z continue-on-errors:

❯ tectonic test.tex -Z continue-on-errors
Running TeX ...
error: test.tex:6: Package microtype Error: Letterspacing currently doesn't work with xetex.

See the microtype package documentation for explanation.
Type  H <return>  for immediate help
warning: errors were issued by the TeX engine, but were ignored; use --print and/or --keep-logs for details.
Running xdvipdfmx ...
Writing `test.pdf` (3.26 KiB)
Skipped writing 1 intermediate files (use --keep-intermediates to keep them)

[rm-dr]

What happens if you compile with xetex?

Judging by that error, I'd assume that microtype doesn't work with xetex (which is what tectonic uses)

[Neved4]

Hey @cgahr great catch! 💙

I can reproduce: when using XeTeX/tectonic the \textls[^1] macro doesn't work, as @rm-dr pointed out. Sadly, this is the expected behaviour now. It may change in the future when microtype adds support for it.[^2]

In general you'd want to use LetterSpace and WordSpace to have a document compatible across pdfTeX/XeTeX/LuaTeX/tectonic.

[^1]: Note that \textls might break small caps when not using SmallCapsFeatures={Letters=SmallCaps} with fontspec. [^2]: microtype's manual specifies that \textls only works with pdfTeX/LuaTeX at the moment.
See §7 Letterspacing revisited, pdfTeX 1.40 | LuaTeX 0.62.

[cgahr]

That is sad to here, it was used in an external beamer-template.

However, something like \newcommand{\textls}[2][1]{\addfontfeature{LetterSpace=40em plus.1em minus.1em} #2} was a sufficient workaround for my use-case. Thank you very much for the pointer!

If you want to reopen this issue open for tracking purposes, please do so, from my side, it can be closed.