we have been discussing the best way to solve this.

An empty list cannot be placed in a scalar, so you could use an empty list.

sub f {
   my $coercion_occurred = 1;  # ...
   my $coerced_value = undef;  # ...

   if ($coercion_occurred) {
       return $coerced_value;
   } else {
       return ();
   }
}

my $coercion_occurred = ($coerced_value) = f();
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