amp-collect-spec-names.php

<?php

$spec_names = [];
foreach ( AMP_Allowed_Tags_Generated::get_allowed_tags() as $tag => $tag_rules ) {
	foreach ( $tag_rules as $tag_rule ) {
		if ( isset( $tag_rule['tag_spec']['spec_name'] ) ) {
			$spec_name = strtolower( $tag_rule['tag_spec']['spec_name'] );
		} elseif ( isset( $tag_rule['tag_spec']['extension_spec']['name'] ) ) {
			$spec_name = sprintf(
				'script[%s=%s]',
				'amp-mustache' === $tag_rule['tag_spec']['extension_spec']['name'] ? 'custom-template' : 'custom-element',
				strtolower( $tag_rule['tag_spec']['extension_spec']['name'] )
			);
		} else {
			$spec_name = $tag;
		}

		if ( isset( $spec_names[ $spec_name ] ) ) {
			echo "Duplicate found: $spec_name";
			exit( 1 );
		}
		$spec_names[ $spec_name ] = true;
	}
}

$spec_names = array_keys( $spec_names );
sort( $spec_names );

echo implode( "\n", $spec_names );