Weird problem with Lato fonts and `\mathrm`

[drs-p]

I found a weird problem when testing different math fonts. I could reduce it to the following MWE:

\documentclass{article}

\usepackage{unicode-math}
\setmainfont{Lato}[
    Numbers = {Lowercase, Proportional},
]

\begin{document}
Test 123: $\mathrm{gcd}(a,b) = c$.
\end{document}

On my machine (Debian 12, x86-64) with a fully up-to-date TeXLive 2025, Lualatex hangs forever when I try to compile this. It works fine when I choose another number style from this font or if I remove the \mathrm. It also works when I add Renderer = OpenType.

I couldn't find anything suspicious in the log file; but just in case it matters, this is the last part:

Package fontspec Info: 
(fontspec)             Font family 'latinmodern-math.otf(2)' created for font
(fontspec)             'latinmodern-math.otf' with options
(fontspec)             [Renderer=Basic,BoldItalicFont={},ItalicFont={},SmallCap
sFont={},Script=Math,SizeFeatures={{Size=8.5-},{Size=6-8.5,Font=latinmodern-mat
h.otf,Style=MathScript},{Size=-6,Font=latinmodern-math.otf,Style=MathScriptScri
pt}},RawFeature={mathfontdimen=xetex},BoldFont={latinmodern-math.otf},RawFeatur
e={mathfontdimen=tex2}].
(fontspec)              
(fontspec)              This font family consists of the following NFSS
(fontspec)             series/shapes:
(fontspec)              
(fontspec)             - 'normal' (m/n) with NFSS spec.:
(fontspec)             <8.5->"[latinmodern-math.otf]:mode=base;script=math;lang
uage=dflt;mathfontdimen=xetex;mathfontdimen=tex2;"<6-8.5>"[latinmodern-math.otf
]:mode=base;script=math;language=dflt;mathfontdimen=xetex;mathfontdimen=tex2;+s
sty=0;"<-6>"[latinmodern-math.otf]:mode=base;script=math;language=dflt;mathfont
dimen=xetex;mathfontdimen=tex2;+ssty=1;"
(fontspec)             - 'bold' (b/n) with NFSS spec.:
(fontspec)             <->"[latinmodern-math.otf]:mode=base;script=math;languag
e=dflt;mathfontdimen=xetex;mathfontdimen=tex2;"

LaTeX Font Info:    Encoding `OMS' has changed to `TU' for symbol font
(Font)              `symbols' in the math version `normal' on input line 8.
LaTeX Font Info:    Overwriting symbol font `symbols' in version `normal'
(Font)                  OMS/cmsy/m/n --> TU/latinmodern-math.otf(2)/m/n on inpu
t line 8.
LaTeX Font Info:    Encoding `OMS' has changed to `TU' for symbol font
(Font)              `symbols' in the math version `bold' on input line 8.
LaTeX Font Info:    Overwriting symbol font `symbols' in ve

It looks as if some more text was buffered, but that was lost when I killed the job.

As I said, I was just testing some fonts and I can work around this by using the OpenType renderer, so please don't spend a lot of time on this.

[davidcarlisle]

Just to confirm, it hangs here as well

[u-fischer]

it looks as if luaotfload doesn't like the combination of mode=base, onum + pnum. This here hangs too:

\documentclass{article}
\begin{document}
Test 123: 
\font\test={name:Lato:mode=base;script=latn;language=dflt;+onum;+pnum;}\test blub
\end{document}

[khaledhosny]

This might be caused by the same underlying issue as #278.