And the reason is that 5.10 doesn't consider "
_" in "
-X _" a function call.
>perl588\bin\perl -MO=Concise -e"sub _; -l _"
7 <@> leave[1 ref] vKP/REFC ->(end)
1 <0> enter ->2
2 <;> nextstate(main 1 -e:1) v ->3
6 <1> ftlink vK/1 ->7
5 <1> entersub[t2] sKS/TARG,1 ->6
- <1> ex-list sK ->5
3 <0> pushmark s ->4
- <1> ex-rv2cv sK/128 ->-
4 <#> gv[*_] s ->5
-e syntax OK
>perl589\bin\perl -MO=Concise -e"sub _; -l _"
7 <@> leave[1 ref] vKP/REFC ->(end)
1 <0> enter ->2
2 <;> nextstate(main 1 -e:1) v ->3
6 <1> ftlink vK/1 ->7
5 <1> entersub[t2] sKS/TARG,1 ->6
- <1> ex-list sK ->5
3 <0> pushmark s ->4
- <1> ex-rv2cv sK/128 ->-
4 <#> gv[*_] s ->5
-e syntax OK
>perl5100\bin\perl -MO=Concise -e"sub _; -l _"
4 <@> leave[1 ref] vKP/REFC ->(end)
1 <0> enter ->2
2 <;> nextstate(main 1 -e:1) v:{ ->3
3 <#> ftlink[*_] vR ->4
-e syntax OK