When typesetting the following MWE with xelatex I obtain an unexpected symbol, an empty square, between the two lines in the equation. It typesets fine in lualatex. The unexpected symbol shows up when using a different font for the text in math mode than for the other symbols, which is a fairly common thing to do. Similar problems have been reported before, such as here: Incompatibility with mathtools and unicode-math in xelatex?

However, the new example does not involved mathtools in any way.

The problem only shows up with certain font sets, as indicated in the MWE, below.

\setmathfont[range=up/{latin,Latin,num}]{XCharter-Roman.otf} % extra character appears between two lines
%\setmathfont[range=up/{latin,Latin,num}]{Charis SIL}  % extra character appears between two lines
%\setmathfont[range=up/{latin,Latin,num}]{texgyretermes-regular.otf}  % works okay with this
%\setmathfont[range=up/{latin,Latin,num}]{Times}  % works okay with this
  x = \begin{cases}
  y \\  y   

And here is the outputenter image description here

Unless I am doing something wrong (always the most likely thing), I guess this is a bug, but I am not sure where - unicode-math, xelatex, the opentype font itself? Is it the same bug as has been reported before?

closed as off-topic by egreg, Stefan Pinnow, Torbjørn T., CarLaTeX, user36296 Jan 10 '18 at 15:33

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  • 1
    It's a known problem: github.com/wspr/unicode-math/issues/351 – egreg Oct 27 '16 at 14:57
  • Pretty serious one, then. It means you can't use different text and math fonts, and use the text font for things like sin, cos, log etc, without the risk of some failure. – GeoffV Oct 27 '16 at 15:53
  • The bug seems to have been solved with unicode-math version 0.8j, released 2018-01-07. – egreg Jan 10 '18 at 12:00
  • 4
    I'm voting to close this question as off-topic because the question is no longer relevant as the bug has been fixed. – egreg Jan 10 '18 at 12:01
  • I guess you saying that a question that is on-topic when posted, because it points to a bug or similar, becomes off-topic when the bug is fixed. Okay. – GeoffV Jan 11 '18 at 13:06