$? = ...; doesn't set the exit code.

Works for me:

perl -e 'END{$?=1}' && echo foo    # prints nothing
perl -e 'END{$?=0}' && echo foo    # prints "foo"
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You can manipulate $? in an END block.  From perlmod:

Inside an "END" code block, $? contains the value that the program is going to pass to "exit()". You can modify $? to change the exit value of the program.