in reply to two versions of libxml2 causing module to fail install
"the version of libxml2.so it (Perl itself?) was compiled against [...] I thought briefly that I should reinstall Perl"
Perl itself does not link to libxml2, so there's no reason to reinstall Perl.
The XML::LibXML Makefile.PL accepts some options for providing the paths to the libxml2 library. You could try installing like e.g.:
Makefile.PL LIBS=/usr/local/lib INC=/usr/local/include make make test sudo make install
package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name
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