in src/core/Node.hack [808:825]
final protected static async function renderChildAsync(
\XHPChild $child,
): Awaitable<string> {
if ($child is node) {
return await $child->toStringAsync();
}
if ($child is \Facebook\XHP\UnsafeRenderable) {
return await $child->toHTMLStringAsync();
}
if ($child is Traversable<_>) {
throw new \Facebook\XHP\RenderArrayException(
'Can not render traversables!',
);
}
/* HH_FIXME[4281] stringish migration */
return \htmlspecialchars((string)$child);
}