[XeTeX] ifcat changed?

Zdenek Wagner zdenek.wagner at gmail.com
Sun Apr 16 12:00:51 CEST 2017

2017-04-16 10:08 GMT+02:00 Julian Bradfield <jcb+xetex at jcbradfield.org>:

> On 2017-04-15, Bruno Le Floch <blflatex at gmail.com> wrote:
> > The primitive conditional "\ifcat\relax\cr true\else false\fi" gives
> > "true" in pdfTeX, LuaTeX, (e)(u)pTeX, and XeTeX from some time ago
> > (could be years), but "false" in XeTeX 0.99996
> Definitely a bug. The TeXbook defines the behaviour of \if and \ifcat,
> and all control sequences are considered to have character code 256
> and category code 16, unless \let equal to a non-active character, in
> which case they have the value of that character.
> Not all control sequences but primitives. Unlike \ifx, \if and \ifcat
perform full expansion.
Try the following code:


The output will be world because $ and A have different category codes.

Similarly, \ifcat\relax\a will compare \relax with $.

Zdeněk Wagner

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