wp-admin/includes/meta-boxes.php:1485Displays post thumbnail meta box.
$postWP_Postfunction post_thumbnail_meta_box( $post ) { $thumbnail_id = get_post_meta( $post->ID, '_thumbnail_id', true ); echo _wp_post_thumbnail_html( $thumbnail_id, $post->ID );}Introduced in 2.9.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/meta-boxes.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.