Source

File: wp-includes/class-wp-user.php

public function get_role_caps() {
		$switch_site = false;
		if ( is_multisite() && get_current_blog_id() != $this->site_id ) {
			$switch_site = true;

			switch_to_blog( $this->site_id );
		}

		$wp_roles = wp_roles();

		// Filter out caps that are not role names and assign to $this->roles.
		if ( is_array( $this->caps ) ) {
			$this->roles = array_filter( array_keys( $this->caps ), array( $wp_roles, 'is_role' ) );
		}

		// Build $allcaps from role caps, overlay user's $caps.
		$this->allcaps = array();
		foreach ( (array) $this->roles as $role ) {
			$the_role      = $wp_roles->get_role( $role );
			$this->allcaps = array_merge( (array) $this->allcaps, (array) $the_role->capabilities );
		}
		$this->allcaps = array_merge( (array) $this->allcaps, (array) $this->caps );

		if ( $switch_site ) {
			restore_current_blog();
		}

		return $this->allcaps;
	}