Re^2: CPAN and "Weak references"

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]

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Re^3: CPAN and "Weak references" by almut (Canon) on Dec 07, 2009 at 21:30 UTC
You might additionally want to check whether `Util.so` is in fact being loaded: `$ strace -efile perl -MScalar::Util=weaken -e'weaken(\my $var)' 2>&1 \| + grep Util\.so` [download] With a working installation, the results should look something like `stat("/usr/lib/perl5/5.8.8/auto/List/Util/Util.so", 0x63b140) = -1 ENO +ENT (No such file or directory) stat("/usr/lib/perl5/5.8.8/x86_64-linux-thread-multi/auto/List/Util/Ut +il.so", {st_mode=S_IFREG\|0555, st_size=40616, ...}) = 0 open("/usr/lib/perl5/5.8.8/x86_64-linux-thread-multi/auto/List/Util/Ut +il.so", O_RDONLY) = 6` [download] Otherwise, you'd get `stat()`s with `ENOENT` only (several dozens, typically), or maybe an attempted `open()` with `EACCES (Permission denied)`, but no successful `open()`	[reply] [d/l] [select]
Re^4: CPAN and "Weak references" by arthurg (Acolyte) on Dec 07, 2009 at 23:37 UTC
Fantastic diagnosis almut and Corion! Reinstalling Scalar::Util fixed the problem, stopping the "Weak references" error, and rendering CPAN operable. You made my day! However, I remain perplexed. I don't understand why this problem occurred or how you diagnosed it. WRT 'why', unfortunately, I don't have a logging filesystem that could show all updates, and even if I did, I don't know how do identify the update(s) that caused this problem. My differential backup shows a change in /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/auto/List/Util/Util.so on 120209, but the problem didn't surface until 12/6/9. I surmise that it didn't surface until the modified file was loaded, but I really don't know. WRT 'how', you say "your Perl did not compile the XS component of Scalar::Util, and your search seems to confirm that for me", but 'locate' found /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/auto/List/Util/Util.so installed (although I should have used 'ls -l' to check its current status) so I didn't see any indication of Scalar::Util installation trouble other than the "Weak references" error. In any case, thanks again monks.	[reply]
Re^3: CPAN and "Weak references" by Corion (Patriarch) on Dec 07, 2009 at 21:22 UTC
But List::Util (to which `List/Util/Util.so` belongs) is a different module than Scalar::Util. Most likely, in your upgrade, your Perl did not compile the XS component of Scalar::Util, and your search seems to confirm that for me. So, reinstall Scalar::Util and make sure you have a matching C compiler for the Perl you're using available, so the XS component gets compiled.	[reply] [d/l]
Re^4: CPAN and "Weak references" by almut (Canon) on Dec 07, 2009 at 21:36 UTC
But List::Util (to which `List/Util/Util.so` belongs) is a different module than Scalar::Util. `List/Util/Util.so` does in fact belong to Scalar::Util (the module is somewhat peculiar in that respect). `$ nm -D /usr/lib/perl5/5.8.8/x86_64-linux-thread-multi/auto/List/Util/ +Util.so \| grep weaken U Perl_sv_rvweaken 0000000000003f70 T XS_Scalar__Util_weaken` [download]	[reply] [d/l] [select]