$ cat junk
while( STDIN ){
    @ARGV=@ARGV;
}
close STDIN ;
$ perl -MO=Concise junk
h  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 3 junk:1) v:{ ->3
d     <2> leaveloop vK/2 ->e
3        <{> enterloop(next->c last->d redo->4) v ->4
-        <@> lineseq vK ->d
4           <;> nextstate(main 1 junk:2) v ->5
b           <2> aassign[t6] vKS/COMMON ->c
-              <1> ex-list lK ->8
5                 <0> pushmark s ->6
7                 <1> rv2av[t5] lK/1 ->8
6                    <#> gv[*ARGV] s ->7
-              <1> ex-list lK ->b
8                 <0> pushmark s ->9
a                 <1> rv2av[t3] lKRM*/1 ->b
9                    <#> gv[*ARGV] s ->a
c           <0> unstack v ->4
e     <;> nextstate(main 3 junk:4) v:{ ->f
g     <1> close vK/1 ->h
f        <#> gv[*STDIN] s ->g
junk syntax OK