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signatures: don't leak an OP_NULL for a '$ =' sigscalarelem #23203

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Merged
merged 3 commits into from
Apr 19, 2025
Merged

signatures: don't leak an OP_NULL for a '$ =' sigscalarelem #23203

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610d65a
signatures: don't leak an OP_NULL for a '$ =' sigscalarelem
tonycoz Apr 10, 2025
0540ee1
subsignature_append_positional: flags is only used in the else
tonycoz Apr 14, 2025
507cff7
perldelta for prevent OP leak for `$ =` signature parameter
tonycoz Apr 14, 2025
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15 changes: 9 additions & 6 deletions op.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16543,19 +16543,22 @@ Perl_subsignature_append_positional(pTHX_ OP *varop, OPCODE defmode, OP *defexpr
if(defexpr) {
signature->optelems++;

I32 flags = 0;
if(defmode == OP_DORASSIGN)
flags |= OPpARG_IF_UNDEF << 8;
if(defmode == OP_ORASSIGN)
flags |= OPpARG_IF_FALSE << 8;

if(defexpr->op_type == OP_NULL && !(defexpr->op_flags & OPf_KIDS))
{
/* caller passed in newOP(OP_NULL, 0), so we should not leak it */
op_free(defexpr);

/* handle '$=' special case */
if(varop)
yyerror("Optional parameter lacks default expression");
}
else {
I32 flags = 0;
if(defmode == OP_DORASSIGN)
flags |= OPpARG_IF_UNDEF << 8;
if(defmode == OP_ORASSIGN)
flags |= OPpARG_IF_FALSE << 8;

/* a normal '=default' expression */
OP *defop = newARGDEFELEMOP(flags, defexpr, argix);

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5 changes: 5 additions & 0 deletions pod/perldelta.pod
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Expand Up @@ -401,6 +401,11 @@ Class initializers and C<ADJUST> blocks, per L<perlclass>, that
called C<last> or other loop exits would crash perl. Same cause as
for [GH #16608].

=item *

Prevent a signature parameter of the form C<$ => from leaking an OP at
compile-time. [GH #23187]

=back

=head1 Known Problems
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