How do you catch recoverable errors in PHP 7+? - php

Question

What happens with set_error_handler() on PHP7 now that all errors are exceptions? makes me think that recoverable errors can be caught but that does not appear to be the case, as demonstrated here:
<?php
$_SERVER['TEST'] = new stdClass;
try {
phpinfo();
} catch (\Throwable $e) {}
If you run that code you'll get this as the output:
$_SERVER['argc'] => 1
$_SERVER['TEST'] =>
Recoverable fatal error: Object of class stdClass could not be converted to string in /Users/username/zzz.php on line 6
So clearly an error is being "issued" but one is not being thrown, unless I'm misunderstanding something?

Answer 1

Not all errors were converted to Throwable errors in PHP 7.
Actually, the docs say:
most errors are now reported by throwing Error exceptions.
(Emphasis mine). Most !== All.
Some errors are still not catchable.
Funnily enough, the error message used you get used to say "Catchable Fatal Error" instead of "Recoverable Fatal Error" before PHP 7.1 was released.
This was reported as a bug, but the solution implemented by the devs was change the error string from Catchable to Recoverable to dispel misconceptions.
In the specific case you are testing, it seems that phpinfo() raises a recoverable error instead of throwing an Error, so it makes sense you can't catch it this way.
Still, not all hope is lost.
What you could do is convert all errors to exceptions by implementing your own error handler. An example of this is described on the ErrorException documentation:
function exception_error_handler($severity, $message, $file, $line) {
if (!(error_reporting() & $severity)) {
// This error code is not included in error_reporting
return;
}
throw new ErrorException($message, 0, $severity, $file, $line);
}
set_error_handler("exception_error_handler");
The neat thing of this example is that it takes into account your error reporting settings, so only errors that would have been reported under your settings are actually thrown as exceptions. Otherwise, nothing happens.
Testing your code:
<?php
function exception_error_handler($severity, $message, $file, $line) {
if (!(error_reporting() & $severity)) {
// This error code is not included in error_reporting
return;
}
throw new ErrorException($message, 0, $severity, $file, $line);
}
set_error_handler("exception_error_handler");
$_SERVER['TEST'] = new stdClass;
try {
phpinfo(INFO_VARIABLES);
} catch (\Throwable $e) {echo 'CAUGHT!!!!!!';}
prints the following output:
$_SERVER['TERM_SESSION_ID'] => w0t1p0:xxx-cxx-xxxxxxx-xxxxx
$_SERVER['SSH_AUTH_SOCK'] => /private/tmp/com.apple.launchd.xxxxxxxx/Listeners
$_SERVER['LC_TERMINAL_VERSION'] => 3.3.2
....
$_SERVER['argc'] => 1
$_SERVER['TEST'] =>
CAUGHT!!!!!!%