Yeah I see your point now.

Seems like Perl is playing safe if a lexpad is required for the closure, even if the closed over lexical variable doesn't change, like here:

$ perl
use v5.14;
my @subs;
sub dosomething :prototype(&) { push @subs, $_[0]; }
my $x;
for (1..2) {
  dosomething { $x+1 }
}
for (1..2) {
  my $x;
  dosomething { $_+1 }
}
say for @subs;
__END__
CODE(0x64405f0de700)
CODE(0x64405f10b340)
CODE(0x64405f118bb0)
CODE(0x64405f118bb0)
[download]

BTW: Clever move to push the code-refs to @subs and keeping them alive instead of printing them out.

Like this you are avoiding that Perl tries to reuse a freed ref again! IOW if we see the same ref again we are sure teh sub wasn't generated again.