use List::Util qw( min );
my @one = (1);

for my $_in (1..5) 
{ 
  push @_x, "$_in";
  my $x_max = min scalar($#_x), $#one;
  print "SET my \$x_max $x_max = min \$#_x $#_x, \$#one $#one;\n";
}

SET my $x_max 0 = min $#_x 0, $#one 0;
SET my $x_max 0 = min $#_x 1, $#one 0;
SET my $x_max 0 = min $#_x 2, $#one 0;
SET my $x_max 0 = min $#_x 3, $#one 0;
SET my $x_max 0 = min $#_x 4, $#one 0;
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Though I don't quite understand why. Real bug perhaps?