[luatex] \luaescapestring and \escapechar

[Hans Hagen]

On 5/16/2014 10:41 PM, Joseph Wright wrote:
> Hello all,
>
> Running some tests today I stumbled across the following issue. With the
> demo:
>
>      \def\test{\luaescapestring{\noexpand\foo}}
>      \escapechar=-1\relax
>      \test
>
> I get
>
>      This is LuaTeX, Version beta-0.79.1 (TeX Live 2014) (rev 4971)
>       restricted \write18 enabled.
>      (./test.tex
>      ! String contains an invalid utf-8 sequence.
>      test ^^@-luaescapestring {noexpand foo }
>
>      l.3 \test
>
>      ?
>
> I was as you'd imagined a bit surprised: I spent a while looking over my
> source for dodgy input before concluding there is something more subtle up.
>
> Is this in some way deliberate or a bug?

\escapechar= 65 : \test == Afoo
\escapechar= 66 : \test == Bfoo
\escapechar=466 : \test == ǒfoo

so,

\escapechar=66 : \test == <utfchar -1>foo

and that is invalid; of course one can argue that -1 should then result 
in no character (in which case one can wonder what then the Lua escape 
character is)

I've added a tracker/

Hans

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