gentoo-overlay/dev-php/swoole/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
<maintainer type="project">
<email>php-bugs@gentoo.org</email>
<name>PHP Project</name>
</maintainer>
<use>
<flag name="http2">Add support for HTTP/2 protocol via <pkg>net-libs/nghttp2</pkg></flag>
</use>
</pkgmetadata>