[tex-k] Bug in web2c or MF: segfault using scantokens in recursive macro

[Dominik Leininger]

Hi Karl,
I tested some other inputs and each of the following lines also throws a 
segfault:
	def?=exitif?enddef;?
	def?=if?enddef;?
	def?=for endfor?enddef;?
	def?=forsuffixes endfor?enddef;?
	forever:scantokens endfor
	forever:exitif endfor
	forever:if endfor
	forever:for endfor endfor
	forever:forsuffixes endfor endfor
The segfault doesn't seem to be necessarily related to recursive macros 
and also happens with forever loops. I don't know if these are separate 
bugs or not, but they may have the same cause.
Hope this helps in tracking down this bug.

Best regards,
Dominik


Am 14.11.2023 um 22:26 schrieb Karl Berry:
> Hi Dominik - thanks for the report. Yikes.
> 
>      I don't know if this is a bug in web2c or in MF. Can someone try to
>      reproduce this behavior with original METAFONT?
> 
> I'll ask. -k