[luatex] Undefined control sequence: message length/truncation

[Joseph Wright]

Hello all,

With the minimal test

\def\use#1{#1}
\use{\foo123456789012345678901234567890123456789012345678901234567890XXXXXXXXXXXXXXY}

pdfTeX and LuaTeX give

! Undefined control sequence.
<argument> \foo

123456789012345678901234567890123456789012345678901234567890...

with the "123" starts at column 16, whereas LuaTeX gives

<argument> \foo

123456789012345678901234567890123456789012345678901234567890XXXXXXXXXXXXXX

with the "123" starting at column 5. I'm not sure why this is:
deliberate or not.

Notice that as well as being out in position, LuaTeX truncates with no
"..." so it's not clear that this has happened: again, is this deliberate?

P.S. Thanks for feedback on other issues.
-- 
Joseph Wright