How can I get PHP to produce a backtrace upon errors?

Question

Trying to debug PHP using its default current-line-only error messages is horrible. How can I get PHP to produce a backtrace (stack trace) when errors are produced?

Answer 1

My script for installing an error handler that produces a backtrace:

') . ' ' . (isset($item['line']) ? $item['line'] : '') . ' calling ' . $item['function'] . '()' . "\n";
    } else {
        echo '
' . "\n";
        echo '  Backtrace from ' . $type . ' \'' . $errstr . '\' at ' . $errfile . ' ' . $errline . ':' . "\n";
        echo '  
' . "\n";
        foreach($trace as $item)
            echo '    
' . (isset($item['file']) ? $item['file'] : '') . ' ' . (isset($item['line']) ? $item['line'] : '') . ' calling ' . $item['function'] . '()
' . "\n";
        echo '  
' . "\n";
        echo '
' . "\n";
    }
    if(ini_get('log_errors')) {
        $items = array();
        foreach($trace as $item)
            $items[] = (isset($item['file']) ? $item['file'] : '') . ' ' . (isset($item['line']) ? $item['line'] : '') . ' calling ' . $item['function'] . '()';
        $message = 'Backtrace from ' . $type . ' \'' . $errstr . '\' at ' . $errfile . ' ' . $errline . ': ' . join(' | ', $items);
        error_log($message);
    }
    if($fatal)
        exit(1);
}

set_error_handler('process_error_backtrace');
?>

Caveat: it is powerless to affect various 'PHP Fatal Errors', since Zend in their wisdom decided that these would ignore set_error_handler(). So you still get useless final-location-only errors with those.