To this humble initiate, it looks like a bug. In the following test program, the text inside the eval seems (correctly) to run in package P; the only difference that prepending 'package P' makes is to set __PACKAGE__ correctly.
[~/perl/test]$ cat package
#!/usr/bin/perl
use warnings;
use strict;
no strict 'vars';
sub speak($) {
print __PACKAGE__, "::speak was passed '", $_[0], "'\n";
}
$var = "\$main::var\n";
$var = $var;
package P;
sub speak($) {
print __PACKAGE__, "::speak was passed '", $_[0], "'\n";
}
$var = "\$P::var\n";
$var = $var;
eval ' speak __PACKAGE__; print $var;';
eval 'package P; speak __PACKAGE__; print $var;';
[~/perl/test]$ ./package
P::speak was passed 'main'
$P::var
P::speak was passed 'P'
$P::var
[~/perl/test]$
Markus
