[tex-k] [NTG-pdftex] Bug#458059:

[Taco Hoekwater]

David Kastrup wrote:
> Frank Küster <frank at debian.org> writes:
> 
>> There is a configuration variable nest_size level, but it doesn't seem
>> to help in this case: The attached file gives an error
>>
>> ! TeX capacity exceeded, sorry [grouping levels=255].
>>
>> although my texmf.cnf has nest_size=500.
> 
> I find it awfully hard to reliably trigger a semantic nest size
> overflow.  The best I have been able to come up with was
> 
> Can anybody think of a semantic nest without grouping apart from
> unrestricted hmode (which I use above)?

The example that was attached by Frank (or Stijn?) does just fine.
As I suspected, the problem is a macro error, not an actual
limit. With \tracingall, the run ends with the output below.

We cannot fix this: the enlarging limits will just result in a
"capacity exceeded" message with a higher counter.

Best wishes,
Taco

------------
\bm at command ...nd \z@ {\bm at gr@@p \boldmath {{b^c}}
                                                   }
\makebm #1$->\bm {#1}
                      $
\bm at mchoice ... {\hbox {#1$\displaystyle \m at th #2$
                                                   }}{\hbox 
{#1$\textstyle \m...

\bm at gr@@p ...fmmode \bm at mchoice #1{#2}{#2}{#2}{#2}
                                                   \else \bfseries #1#2\fi
\bm at command ...nd \z@ {\bm at gr@@p \boldmath {{b^c}}
                                                   }
\makebm #1$->\bm {#1}
                      $
\bm at mchoice ... {\hbox {#1$\displaystyle \m at th #2$
                                                   }}{\hbox 
{#1$\textstyle \m...

\bm at gr@@p ...fmmode \bm at mchoice #1{#2}{#2}{#2}{#2}
                                                   \else \bfseries #1#2\fi
\bm at command ...30049 ^{\bm at gr@@p \boldmath {{b^c}}
                                                   }
\makebm #1$->\bm {#1}
                      $
\makelabel ...h {\makebm }\normalfont \bfseries #1
                                                   :}
\sbox #1#2->\setbox #1\hbox {\color at setgroup #2
                                                \color at endgroup }
\@item ...i \fi \sbox \@tempboxa {\makelabel {#1}}
                                                   \global \setbox 
\@labels \...
l.11 \item[$a^{b^c}$]
                       $a^{b^c}$
!  ==> Fatal error occurred, no output PDF file produced!

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