Note that It can't safely be optimised that way at compile-time. Consider

sub f {
   my @a;
   tie @a, 'SomeClass' if $_[0];
   g(\@a);
   return [ @a ];
}
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If @a or one of its elements is magical, if an element of @a overloads =, or if the REFCNT of @a or one of its elements is greater than one, then the optimisation can't be applied.

So if f's first argument is true, then the optimisation can't be applied. If g saved the reference to @a, then the optimisation can't be applied. etc.

We're talking about a massive amount of resources to avoid a rare annoyance. Make a perlcritic rule instead.