[tex-live] Re: [tex-implementors] Re: bug in etex

[Philip TAYLOR]

Olaf Weber wrote:

[snip]

> This does not happen on those systems where min_halfword is defined as
> 0, as mem[0] and mem[1] are valid array accesses, even if they are
> semantically invalid in the code doing those accesses.

Intriguingly, Knuth writes :

	The minimum halfword value represents a null pointer.
	\TeX\ does not assume that |mem[null]| exists.

whilst in the EteX Pascal source, we find :

	CHAA:[006.E-TEX.VMS]ETEX.PAS;2

	MEM[0].HH.RH:=MEM[0].HH.RH+530;{:228}{232:}EQTB[11312].HH.RH:=0;
	IF T<=3 THEN BEGIN MEM[CURPTR+1].HH.RH:=0;MEM[0].HH.RH:=MEM[0].HH.RH+1;
	IF S<>0 THEN BEGIN MEM[0].HH.RH:=MEM[0].HH.RH+1;DELETEGLUEREF(S);
	INT=0)THEN BEGIN MEM[0].HH.RH:=MEM[0].HH.RH+1;DELETEGLUEREF(CURVAL);

There's no conflict, but it is intriguing to see that MEM[0] is explicitly
referenced at a few points in the code ...

** Phil.