Thanks Almut, but that doesn't seem to be the case; auto/List/Util/Util.so is in an element of @INC: 
$ perl -MScalar::Util=weaken -e'weaken(\my $var)'
Weak references are not implemented in the version of perl at -e line 
+0
BEGIN failed--compilation aborted.

[download]
$ locate Util.so
/usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/auto/List/Util/Util.s
+o
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/APR/
+Util/Util.so
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/Apac
+he2/ConnectionUtil/ConnectionUtil.so
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/Apac
+he2/RequestUtil/RequestUtil.so
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/Apac
+he2/ServerUtil/ServerUtil.so
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/Apac
+he2/Util/Util.so
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/ModP
+erl/Util/Util.so

[download]

$ perl -e 'print join( "\n", @INC), "\n";'
/usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.8
/usr/lib/perl5/site_perl
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.8
/usr/lib/perl5/vendor_perl
/usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi
/usr/lib/perl5/5.8.8
.

[download]

In reply to Re^2: CPAN and "Weak references" by arthurg
in thread CPAN and "Weak references" by arthurg

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