ok, let me refine my comment:

DESTROY methods should not have side effects like changing $@ unless they do it while dieing

In other words, I have no problem if some DESTROY method dies and changes $@ while doing it.

In practice, what I mean is that inside a DESTROY sub, if eval is used, $@ should be localized for its scope (and the same applies for $! and IO operations and $? and system, fork, etc.)

For instance, I see no problem with this DESTROY method:

sub DESTROY {
  my $self = shift;
  { local $@; eval { $self->whatever() }; }
  die "cleanup failed" unless $self->cleanup;
}
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Regarding the p5p discussion, it was about whether this no-side-effects-from-DESTROY thing should be implemented at the interpreter level.