[pdftex] \ifincsname nesting bug

[Will Robertson]

Hi,

This was reported on the XeTeX mailing list but I'm reposting here since I think it's more appropriate for this list. (Fixes to pdfTeX can then propagate to the other engine(s).)

Here's a minimal example:

\def\a{\ifincsname T \else F \fi}
\expandafter\string\csname
    1\a
    \expandafter\string\csname2\a\endcsname
    3\a
\endcsname

#1 and #2 are "true" but #3 is "false". It seems like the first \endcsname has reset the "am i in a csname" switch rather than popped it back to its previous value.

Cheers,
-- Will