#1201 Generation of cross-reference with invalid target (typo) crashes cobc

[Simon Sobisch]

simplest reproducer:

$> echo 'MOVE 5 TO typo' | cobc -frelax-syntax -w -free - -t - -Xref 1>/dev/null
<stdin>:1: error: 'typo' is not defined
free(): invalid pointer

Does not happen with GC 3.1, but since GC 3.2.

The reason is that cobc_xref_set_receiving() expects a reference - but does not check the type of the reference (here the error node) and simply casts that to a field, something that is only asserted with --enable-cobc-internal-checks during configure, which leads to

cobc: cobc.c:6108: invalid cast from 'internal error node' type CONSTANT to type FIELD

cobc: aborting compile of <stdin> at line 2 (PROGRAM-ID: a)

cobc: Please report this!

fixed by the following patch

@@ -6122,10 +6097,15 @@
        if (CB_CAST_P (target)) {
                target = CB_CAST (target)->val;
        }

-       if (!CB_REF_OR_FIELD_P (target)) {
+       if (CB_REFERENCE_P (target)) {
+               /* note: we may get cb_error_node out here... */
+               target = cb_ref (target);
+       }
+       /* ... which is no field */
+       if (!CB_FIELD_P (target)) {
                return;
        }
-       target_fld = CB_FIELD_PTR (target);
+       target_fld = CB_FIELD (target);
        target_fld->count++;
 #ifdef COB_INTERNAL_XREF
        if (CB_REFERENCE_P (target)) {