ref: 10e72d182aad860492f6ec2e80b0c05a4dc20b7a
dir: /test/t.sub0/
{sub(/[aeiou]/, "foo"); print}
{sub("[aeiou]", "foo"); print}
{gsub(/[aeiou]/, "foo"); print}
{gsub("[aeiou]", "foo"); print}
{sub(/[aeiou]/, "&foo"); print}
{sub("[aeiou]", "&foo"); print}
{gsub(/[aeiou]/, "&foo"); print}
{gsub("[aeiou]", "&foo"); print}
{sub(/[aeiou]/, "\&foo"); print}
{sub("[aeiou]", "\&foo"); print}
{gsub(/[aeiou]/, "\&foo"); print}
{gsub("[aeiou]", "\&foo"); print}