wp-includes/IXR/class-IXR-value.php:127Checks whether or not the supplied array is a struct or not
$arrayarraybool function isStruct($array) { $expected = 0; foreach ($array as $key => $value) { if ((string)$key !== (string)$expected) { return true; } $expected++; } return false; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/IXR/class-IXR-value.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.