[9fans] troff pic bug report -> acid debug -> no fix yet

[Fernan Bolando <fernanbolando@mailc.net>]

Hi all

Here is a bug report for troffs pic preprocessor.
It crashes when the commands is in a square bracket and you loose
track of the labels


-----------> test file contents
pseudo@helios; cat test.p
.PS

define missing { [
	O: box invis wid 2.5 ht 1;
	circle diam 0.1 with .e at P1;
] }

missing with .c at 0,0

.PE

-------> crash report and acid
pseudo@helios; cat test.p | pic
.lf 1 -
pic: no such place as P1 near -:8
 context is
		circle diam 0.1 with .e at >>>  P1; <<<  with .c at 0,0
pic 44699: suicide: sys: trap: fault read addr=0x10 pc=0x89b9
pseudo@helios; acid 44699
/proc/44699/text:386 plan 9 executable
/sys/lib/acid/port
/sys/lib/acid/386
acid: src(0x89b9)
/sys/src/cmd/pic/circgen.c:49
 44			case WITH:
 45				with = ap->a_val.i;
 46				break;
 47			case AT:
 48				ppos = ap->a_val.o;
>49				curx = ppos->o_x;
 50				cury = ppos->o_y;
 51				at++;
 52				break;
 53			case INVIS:
 54				battr |= INVIS;
acid: