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<?php

add_filter('ywrac_coupon_args','ywrac_coupon_args');
function ywrac_coupon_args( $args ){

	$product_on_sale = wc_get_product_ids_on_sale();
	if( is_array( $product_on_sale) && !empty( $product_on_sale ) ){
		$args['exclude_product_ids'] = implode( ',', $product_on_sale );
	}

	return $args;
}