initial implementation of lvalue subroutines (slightly fixed

version of patch suggested by Ilya Zakharevich, which in turn
is based on the one suggested by Tuomas J. Lukka <lukka@iki.fi>)

p4raw-id: //depot/perl@4081

1 files changed, 2 insertions, 0 deletions

diff --git a/pp.c b/pp.c
index cde539cf84..4d96370f7e 100644
--- a/pp.c
+++ b/pp.c
@@ -375,6 +375,8 @@ PP(pp_rv2cv)
     if (cv) {
 	if (CvCLONE(cv))
 	    cv = (CV*)sv_2mortal((SV*)cv_clone(cv));
+	if ((PL_op->op_private & OPpLVAL_INTRO) && !CvLVALUE(cv))
+	    Perl_croak(aTHX_ "Can't modify non-lvalue subroutine call");
     }
     else
 	cv = (CV*)&PL_sv_undef;