"The installed system version of libxml2 2.9.4 is not compatible with XML::LibXML (and probably buggy)!"
...
# Failed test 'xs'
# at t/alien_libxml2.t line 10.
#   ExtUtils::CBuilder->compile failed
#     error building testalienjPkRO/test.o from 'testalienjPkRO/test.c' at /Users/psharman/perl5/perlbrew/perls/perl-5.30.0/lib/5.30.0/ExtUtils/CBuilder/Base.pm line 185.
#     cc -I/Users/psharman/perl5/perlbrew/perls/perl-5.30.0/lib/5.30.0/darwin-2level/CORE -I/usr/include/libxml2 -c -fno-common -DPERL_DARWIN -mmacosx-version-min=10.14 -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -DPERL_USE_SAFE_PUTENV -O3 -o testalienjPkRO/test.o testalienjPkRO/test.c
#     testalienjPkRO/test.xs:5:10: fatal error: 'libxml/parser.h' file not found
#     #include <libxml/parser.h>
#              ^~~~~~~~~~~~~~~~~>