Integrate:

[ 26108]
BEGIN blocks should start a new stack, as they can be called as a
side effect of "regular" Perl API calls within subroutines that have
already cached the current stack's address. If they don't, any stack
extension during the call may move the stack, rendering that cached
value invalid without the cachee realising. (For example, PP code
calling gv_fetchpv() which triggers a load of Errno.pm)
p4raw-link: @26108 on //depot/maint-5.8/perl: 5480675bc37b4a804a56a749cdedc70e27a270eb

p4raw-id: //depot/perl@26110
p4raw-integrated: from //depot/maint-5.8/perl@26107 'merge in' op.c
	(@26097..)

1 files changed, 3 insertions, 0 deletions

diff --git a/op.c b/op.c
index 03ca56e331..a3dee91b33 100644
--- a/op.c
+++ b/op.c
@@ -4538,8 +4538,10 @@ Perl_newATTRSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
 	    goto done;
 
 	if (strEQ(s, "BEGIN") && !PL_error_count) {
+	    dSP;
 	    const I32 oldscope = PL_scopestack_ix;
 	    ENTER;
+	    PUSHSTACKi(PERLSI_REQUIRE);
 	    SAVECOPFILE(&PL_compiling);
 	    SAVECOPLINE(&PL_compiling);
 
@@ -4552,6 +4554,7 @@ Perl_newATTRSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
 
 	    PL_curcop = &PL_compiling;
 	    PL_compiling.op_private = (U8)(PL_hints & HINT_PRIVATE_MASK);
+	    POPSTACK;
 	    LEAVE;
 	}
 	else if (strEQ(s, "END") && !PL_error_count) {