Note that in older versions of Perl you'll need a newline in front of the #line directive.

Note also that you can make the line number and file name actually match where the eval'd code is. For example, Algorithm::Loops' t/assert.t evals a bunch of code after __END__ but makes any fatal errors report the correct line number via:

# ...
my $lineNum;
sub SetLineNum { $lineNum= 1+(caller(0))[2]; }
while(  <DATA>  ) {
    $lineNum++;
# ...
        eval "\n#line $lineNum $0\n$_\n; 1"
          or  die $@;
# ...
}
# ...

BEGIN { SetLineNum }
__END__
# ...
[download]

More typical tricks just use __LINE__ (plus a constant) and __FILE__:

my $file= '"' . __FILE__ . '"';
eval join " ", "\n#line", 1+__LINE__, $file, "\n", <<END, "; 1" or die
+ $@;
...
END
[download]

Though, you might want to do a bit extra work if you are on an operating system that allows obnoxious things like file names that contain double quotes.