Treating Warnings as Errors

Question

I have a php application that I have just re-factored. Unfortunately it spewing out warnings like:

Warning: preg_match() expects parameter 2 to be string, object given in /home/yacoby/dev/netbeans/php/Zend/Db/Select.php on line 776

Which is impossible (or very hard work) to work out the issue as I don't have a callstack so can't tell which parts of my code are causing the warning and there is a lot of code.

I need a method to either treat warnings like errors (In that the application dies and prints the stacktrace) or I need the stacktrace to be shown when printing errors. Is there a method to do this?

Answer 1

XDebug speaks about such a feature here http://xdebug.org/docs/stack_trace

Answer 2

You can define your own error handler using set_error_handler()

In the handler function you can treat each class of error however you want. Here's a basic template that I use, in my case I only want to handle fatal errors, so I ignore notices and warnings.

In your case you could do a backtrace on warnings, or log them however you want

function error_handler($errno,$message,$file,$line,$context) {

switch($errno) {
    // ignore warnings and notices
    case E_WARNING:
    case E_NOTICE:
    case E_USER_NOTICE:
    case E_USER_WARNING:
        break;
    // log PHP and user errors
    case E_ERROR:
    case E_USER_ERROR:
              // Do some processing on fatal errors
    }
}

Answer 3

See example #1 at http://www.php.net/manual/en/class.errorexception.php

Answer 4

Have a look at set_error_handler() and include this at the beginning of your scripts or in your bootstrap to just print the stacktrace when E_WARNINGs occur.

function stacktrace_error_handler($errno,$message,$file,$line,$context)
{
    if($errno === E_WARNING) {
        debug_print_backtrace();
    }
    return false; // to execute the regular error handler
}
set_error_handler("stacktrace_error_handler");

For more control over the various types, have a look at the more explicit version posted elsewhere in the answers.