longmess and shortmess do include caller information. The key is how deep you are in the stack, as Carp has a set of rules for deciding how much stack trace (if any) to include. I'm not 100% sure the rules are consistent across all the calls. Here's a test program that illustrates. Maybe a monk with more Carp knowledge can comment. I need to think about it some more ... I suspect there's some nonobvious consistency here.

use strict;
use Carp qw(cluck);

sub test_errors
{
    cluck "First test message";

    my $long  = Carp::longmess("Second test message");
    my $short = Carp::longmess("Third test message");

    print STDERR $long;
    print STDERR $short;

    test2();
}

sub test2
{
    cluck "Fourth test message";

    my $long  = Carp::longmess("Fifth test message");
    my $short = Carp::longmess("Sixth test message");

    print STDERR $long;
    print STDERR $short;
}

test_errors();
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First test message at cluckt line 8
        main::test_errors() called at cluckt line 30
Second test message at cluckt line 30
Third test message at cluckt line 30
Fourth test message at cluckt line 21
        main::test2() called at cluckt line 16
        main::test_errors() called at cluckt line 30
Fifth test message at cluckt line 16
        main::test_errors() called at cluckt line 30
Sixth test message at cluckt line 16
        main::test_errors() called at cluckt line 30
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Basically, longmess and shortmess appear to always include one less stack frame than cluck does. Maybe someone should cluck about this. ;-)

If I understand your question, I think you are looking for information available in caller. You don't want to know who called you, but who called something that called you.

use strict;
use Carp;

trace('foo');
trace('bar');

func();


sub func
{
  trace('in func');
}

sub trace
{
  my $string = shift;
  my  ($package, $filename, $line, $subroutine, $hasargs,
       $wantarray, $evaltext, $is_require, $hints, $bitmask) = caller(
+1);
  
  if($subroutine)
  {
    print "[$subroutine]: $string\n";
  }
  else
  {
    print "[**IN MAIN**]: $string\n";
  }
}
__END__
[**IN MAIN**]: foo
[**IN MAIN**]: bar
[main::func]: in func
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