Looks like weaken doesn't support CODE: 
$ perl -MScalar::Util=weaken -E '$a={};   weaken($b=$a);$a=0;say $b'

$ perl -MScalar::Util=weaken -E '$a=sub{};weaken($b=$a);$a=0;say $b'
CODE(0x5964f33f920)

[download]
Is this a bug or feature? Tested on perl-5.12.4, Scalar::Util-1.35.

Update: More details on https://rt.cpan.org/Ticket/Display.html?id=90227

In reply to weaken CODEREF by powerman

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