For a document like
\documentclass{article}
\usepackage[T1]{fontenc}
\input glyphtounicode.tex
\input glyphtounicode-cmr.tex
\pdfgentounicode=1
\pagestyle{empty} % for quick CTRL+A
\begin{document}
Some text and then $x$.
Some text and then $\int_0^1 x$.
\end{document}
Trying to copy-paste yields
Some text and then x.
Some text and then ∫ 1
0
x.
Now, I guess the interval isn’t really properly expressible in plain text (unless it can be done through some funky Unicode composition), but I would not expect the result to be that bad – maybe ∫0 1 x? Is there something I can do for better results?

accsupp– Henri Menke Sep 24 '17 at 09:52amsmath)? – timo_k Sep 24 '17 at 12:29