Fatal error with ConTeXt mkiv in TL 2025

[Bruno Voisin]

Hi Max,

> I've reported the issue upstream
> 
>    https://mailman.ntg.nl/archives/list/ntg-context@ntg.nl/thread/GCITK22RNY5KTA2J2GRPGP64FVIVAOF6/
> 
> so it should hopefully be fixed soonish.

Thanks for this.

>> I couldn't figure out how \pi is defined in mkiv.
> 
> It should be defined in "char-ent.lua" or "char-def.lua" (I think?),
> although I'm not sure why that's not working, since the other symbols
> defined in those files work just fine.

The problem was introduced by today's update (context.r74156), it wasn't present with the version before that (context.r72745).

It turns out the definition in char-def.lua from r72745

	 [0x3C0]={
	  category="ll",
	  cjkwd="a",
	  contextname="greekpi",
	  description="GREEK SMALL LETTER PI",
	  direction="l",
	  linebreak="al",
	  mathclass="variable",
	  mathname="pi",
	  synonyms={ "mathematical constant 3.141592... pi", "mathematical constant pi" },
	  uccode=0x3A0,
	  unicodeslot=0x3C0,
	 },

has been replaced in r74156 with

	 [0x3C0]={
	  category="ll",
	  cjkwd="a",
	  contextname="greekpi",
	  description="GREEK SMALL LETTER PI",
	  direction="l",
	  linebreak="al",
	  mathclass="variable",
	  mathname="mathpiuprightshape",
	  synonyms={ "mathematical constant 3.141592... pi", "mathematical constant pi" },
	  uccode=0x3A0,
	  unicodeslot=0x3C0,
	 },

As a consequence, \pi is replaced by \mathpiuprightshape.

Indeed, using \mathuprightshape instead of \pi in Hello-World.tex allows it to typeset.

ConTeXt mkxl includes a new file math-con.mkxl in r74156, telling

	\permanent\protected\def\pi{\math_upright_constant\s!pi           \mathpiuprightshape\mathpiitalicshape}

It seems adding the same definition to mkiv is the backporting Hans is talking about at

	https://mailman.ntg.nl/archives/list/ntg-context@ntg.nl/thread/GCITK22RNY5KTA2J2GRPGP64FVIVAOF6/

Bruno