wp-includes/class-wp-query.php:4120Makes private properties checkable for backward compatibility.
$namestringbool public function __isset( $name ) { if ( in_array( $name, $this->compat_fields, true ) ) { return isset( $this->$name ); } return false; }Introduced in 4.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-query.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.