I noticed that B::Xref had problems listing a subroutine so I took a look into the optree only to see that the name isn't properly displayed there.

file 1 and 2 are only different in the order of sub definition and call. as you can see at the line marked as ### the name fooxx is missing in version 2.

What's the problem?

I actually also did a Xref,-r which was buggy too, (the definition of &fooxx was located in in the B.pm file) but the output is just too verbose, to be shown here.

D:\exp>perl -MO=Xref,-d t_XREF_bug1.pl
File t_XREF_bug1.pl
  Subroutine (main)
    Package main
      &fooxx            &1                       ###
t_XREF_bug1.pl syntax OK

D:\exp>perl -MO=Xref,-d t_XREF_bug2.pl
File t_XREF_bug2.pl
  Subroutine (main)
    Package (lexical)
      &?                &4                       ###
t_XREF_bug2.pl syntax OK

D:\exp>


D:\exp>type t_XREF_bug1.pl
fooxx();
sub fooxx {
    print @_;
}



D:\exp>perl -MO=Concise,-stash="main",-main,-src t_XREF_bug1.pl
FUNC: *main::fooxx                                              ###
6  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->6
# 3:     print @_;
1        <;> nextstate(main 2 t_XREF_bug1.pl:3) v ->2
5        <@> print sK ->6
2           <0> pushmark s ->3
4           <1> rv2av[t2] lK/1 ->5
3              <#> gv[*_] s ->4
main program:
c  <@> leave[1 ref] vKP/REFC ->(end)
7     <0> enter ->8
# 1: fooxx();
8     <;> nextstate(main 1 t_XREF_bug1.pl:1) v:{ ->9
b     <1> entersub[t2] vKS/TARG ->c
-        <1> ex-list K ->b
9           <0> pushmark s ->a
-           <1> ex-rv2cv sK/1 ->-
a              <#> gv[*fooxx] s/EARLYCV ->b                       ###
# 6:
-     <;> ex-nextstate(main 3 t_XREF_bug1.pl:6) v:{ ->c
t_XREF_bug1.pl syntax OK

D:\exp>type t_XREF_bug2.pl
sub fooxx {
    print @_;
}
fooxx();

D:\exp>perl -MO=Concise,-stash="main",-main,-src t_XREF_bug2.pl
FUNC: *main::constant::                                           ###
6  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->6
# 2:     print @_;
1        <;> nextstate(main 2 t_XREF_bug2.pl:2) v ->2
5        <@> print sK ->6
2           <0> pushmark s ->3
4           <1> rv2av[t2] lK/1 ->5
3              <#> gv[*_] s ->4                               
main program:
c  <@> leave[1 ref] vKP/REFC ->(end)
7     <0> enter ->8
# 4: fooxx();
8     <;> nextstate(main 3 t_XREF_bug2.pl:4) v:{ ->9
b     <1> entersub vKS ->c
-        <1> ex-list K ->b
9           <0> pushmark s ->a
-           <1> ex-rv2cv sK/1 ->-
a              <#> gv[IV \] s ->b                                 ###
t_XREF_bug2.pl syntax OK

D:\exp>
[download]

update

B::Deparse seems to get it right though.