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Postings from November 1999
----------------------------------------XS--------
MODULE = Test PACKAGE = Test
SV*
test(...)
CODE:
RETVAL = &PL_sv_undef;
OUTPUT:
RETVAL
---------------------------------------perl-------
use Test;
$a = \undef; # will increment refcount on PL_sv_undef
$a = Test::test(); # perl5.004_05 will die "Modification of a read-only value attempted"
--------------------------------------------------
Does anybody know which patch to perl5.004_05 introduced this behaviour?
Is it wrong to return &PL_sv_undef as shown above?
The fix that I have now applied to HTML/Parser.xs is this one:
Index: Parser.xs
===================================================================
RCS file: /home/cvs/aas/perl/mods/html-parser/Parser.xs,v
retrieving revision 2.40
retrieving revision 2.41
diff -u -p -u -r2.40 -r2.41
--- Parser.xs 1999/11/25 11:22:22 2.40
+++ Parser.xs 1999/11/25 11:59:52 2.41
@@ -1624,7 +1624,16 @@ accum(pstate,...)
PSTATE* pstate
CODE:
RETVAL = pstate->accum ? newRV_inc((SV*)pstate->accum)
- : &PL_sv_undef;
+#if !(PATCHLEVEL == 4 && SUBVERSION == 5)
+ : &PL_sv_undef
+#else
+ /* For perl5.004_05 returning PL_sv_undef will terminate
+ * the program with the "Modification of a read-only value attempted"
+ * message if its reference count happen to be incremented.
+ * Returning a copy is then better.
+ */
+ : newSVsv(&PL_sv_undef);
+#endif
if (items > 1) {
SV* aref = ST(1);
AV* av = (AV*)SvRV(aref);
Regards,
Gisle