WordPress nested taxonomy + custom post type loop example

wp-nested-tax-cpt-loop.php

<?php
$post_type = 'post_type';
$taxonomy  = 'taxonomy';
$terms     = get_terms( $taxonomy );
?>
<?php

if ( ! empty( $terms ) && ! is_wp_error( $terms ) ) {

	foreach ( $terms as $term ) { ?>

        <h2><?php echo $term->name; ?></h2>

		<?php
		$args = array(
			'post_type'      => $post_type,
			'posts_per_page' => - 1,
			'tax_query'      => array(
				array(
					'taxonomy' => $taxonomy,
					'field'    => 'slug',
					'terms'    => $term->slug,
					'operator' => 'IN'
				)
			),
		);

		$q = new WP_Query( $args );

		if ( $q->have_posts() ) : ?>

			<?php while ( $q->have_posts() ) : $q->the_post(); ?>

				<?php the_title(); ?>

			<?php endwhile; ?>

		<?php endif; ?>

		<?php wp_reset_query(); ?>

	<?php }

}