$ go build
# github.com/jackc/pgtype
./aclitem_array.go:90:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./bool_array.go:92:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./bpchar_array.go:92:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./bytea_array.go:73:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./cidr_array.go:112:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./date_array.go:93:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./enum_array.go:90:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./float4_array.go:92:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./float8_array.go:92:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./hstore_array.go:73:49: reflectedValue.IsZero undefined (type reflect.Value has no field or method IsZero)
./hstore_array.go:73:49: too many errors
$ go version
go version go1.12.9 linux/amd64
$
IsZero method was added in go 1.13