lanx@nc10-ubuntu:/tmp$ perl -MO=Concise, -e 'do ($foo)->{bar};'
9  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
8     <1> dofile vK/1 ->9                     # do file
7        <2> helem sK/2 ->8                     # hash-elem returns file  
5           <1> rv2hv[t2] sKR/1 ->6
4              <1> rv2sv sKPM/DREFHV,1 ->5
3                 <#> gv[*foo] s ->4
6           <$> const[PV "bar"] s/BARE ->7
-e syntax OK

lanx@nc10-ubuntu:/tmp$ perl -MO=Concise, -e 'print ($foo)->{bar};'
9  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
8     <2> helem vK/2 ->9                      # hash-element
6        <1> rv2hv[t2] sKR/1 ->7
5           <@> print sK ->6                    # print returns hashref
3              <0> pushmark s ->4
-              <1> ex-rv2sv sK/1 ->5
4                 <#> gvsv[*foo] s ->5
7        <$> const[PV "bar"] s/BARE ->8
-e syntax OK

##</code><code>##

$ perl -c -e  'print (caller)[5]'
syntax error at -e line 1, near ")["
-e had compilation errors.

##</code><code>##

$ perl -c -e  'do (L,I,S,T)[5]'
-e syntax OK