Your sample program is a bit convoluted to be useful, so I wrote my own:

#!/usr/bin/perl

use Carp;

eval { croak "With a newline\n" }; print $@;

eval { croak "No newline" }; print $@;
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Here's my output on perl v5.8.4 built for darwin-2level. With a newline, there is nothing after the message "With a newline", although croak still tell me where it happened. After the message "No newline", I get the file name and line number, and croak still tells me a little bit about where this happened.

With a newline
        eval {...} called at croak.pl line 5
No newline at croak.pl line 7
        eval {...} called at croak.pl line 7
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This is the output I expect: If I'm using croak(), I want that information about the caller. That's a separate issue from tacking on the filename and line number though.