Error in wp-includes/functions.php

Here’s the function that includes line 2758 (line 2758 is the line starting with trigger_error).

/**
 * Marks something as being incorrectly called.
 *
 * There is a hook doing_it_wrong_run that will be called that can be used
 * to get the backtrace up to what file and function called the deprecated
 * function.
 *
 * The current behavior is to trigger a user error if WP_DEBUG is true.
 *
 * @package WordPress
 * @subpackage Debug
 * @since 3.1.0
 * @access private
 *
 * @uses do_action() Calls 'doing_it_wrong_run' and passes the function arguments.
 * @uses apply_filters() Calls 'doing_it_wrong_trigger_error' and expects boolean value of true to do
 *   trigger or false to not trigger error.
 *
 * @param string $function The function that was called.
 * @param string $message A message explaining what has been done incorrectly.
 * @param string $version The version of WordPress where the message was added.
 */
function _doing_it_wrong( $function, $message, $version ) {

	do_action( 'doing_it_wrong_run', $function, $message, $version );

	// Allow plugin to filter the output error trigger
	if ( WP_DEBUG && apply_filters( 'doing_it_wrong_trigger_error', true ) ) {
		$version = is_null( $version ) ? '' : sprintf( __( '(This message was added in version %s.)' ), $version );
		$message .= ' ' . __( 'Please see <a href="http://codex.wordpress.org/Debugging_in_WordPress">Debugging in WordPress</a> for more information.' );
		trigger_error( sprintf( __( '%1$s was called <strong>incorrectly</strong>. %2$s %3$s' ), $function, $message, $version ) );
	}
}