Lualatex: escaping of > by \textgreater{} is not enough, >> applies ligature

[jfbu]

Sphinx LaTeX escapes > in source to \textgreater{} in produced TeX file. Unfortunately with lualatex, \textgreater{}\textgreater{} becomes a ligature: ». This is not the case with xelatex or pdflatex.

This showed up as real-life problem when trying to build the PDFs of the CPython documentation using lualatex, as Python wants >>> indexed of course!

[tk0miya]

It seems >> (not \textgreater{} is also combined to ». It should be change behavior of ligature for LuaLaTeX.

\documentclass{report}

\begin{document}
Ligature test: >> and \textgreater{}\textgreater{}
\end{document}

[jfbu]

@tk0miya To prevent ligature I was recommended upstream by David Carlisle to use either \textgreater\/ or \mbox{\textgreater}.

side-note: for literals and code-blocks, preventing >> TeX ligature is achieved via other means and needs no fix for lualatex

[jfbu]

By the way also -{}- or -{-} mark-up with LuaLaTeX give via ligature a long dash rather than -- in PDF. One does not see it easily in Sphinx documents, as in this example from our own doc sphinx.tex:

\pysigline{\sphinxbfcode{\sphinxupquote{-q}}\sphinxcode{\sphinxupquote{}}\sphinxcode{\sphinxupquote{,~}}\sphinxbfcode{\sphinxupquote{-{-}quiet}}\sphinxcode{\sphinxupquote{}}}

because:

1. fontspec does not apply Ligatures = TeX for mono font, which is triggered by \sphinxcode or \sphinxbfcode by default,

2. additionally \sphinxupquote does extra things with - which also make ligature impossible.

But with LuaLaTeX and a non-monospace font, input such as -{}- or -{-} does create ligature. (contrarily to pdflatex/xelatex)