use 5.010;
sub f {
    my $x = shift;
    sub () { $x }
}
say f(1);
say f(2);
__END__
CODE(0x18cede8)
CODE(0x18cede8)

##</code><code>##

use 5.010;
sub f {
    my $x = shift;
    sub () { $x }
}
say my $x = f(1);
say f(2);
__END__
CODE(0x1d5cde8)
CODE(0x1d5cf98)

##</code><code>##

perl -MO=Concise,f -e 'sub f { my $x = shift; sub () { $x } };'
main::f:
9  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->9
1        <;> nextstate(main 1 -e:1) v ->2
4        <2> sassign vKS/2 ->5
2           <0> shift s* ->3
3           <0> padsv[$x:1,3] sRM*/LVINTRO ->4
5        <;> nextstate(main 3 -e:1) v ->6
8        <1> refgen K/1 ->9
-           <1> ex-list lKRM ->8
6              <0> pushmark sRM ->7
7              <$> anoncode[CV ""] lRM ->8
-e syntax OK