#88 Extended ^^ notation (five or more digits) fails inside \csnames

[Joseph Wright]

For example,

\show ^^^^^10400
\showtokens\expandafter{\csname ^^^^^10400\endcsname}

gives the output:

> the letter 𐐀.
l.4 \show ^^^^^10400

? 
> \The `$' that I just saw supposedly matches a previous `$$'. .
l.5 ...s\expandafter{\csname ^^^^^10400\endcsname}

which looks very much like other defective behaviours with ^^ notation.

[Jonathan Kew]

This isn't primarily an issue with ^^^^^ notation, but rather a problem with control sequence names that consist of a single higher-plane character.

Compare:

    \showtokens\expandafter{\csname 𐐀\endcsname}

which fails similarly; as does the simple

    \showtokens{\𐐀}

On the other hand,

    \showtokens\expandafter{\csname ^^^^^10400^^^^^10401\endcsname}

works as expected.

[Jonathan Kew]

Fix pushed to utf16-issues branch; will merge to master shortly.

[Arthur Reutenauer]

This bug should be fixed by Jonathan’s changes in TeX Live 2015.