Please provide short (~20 lines max) reproduce case.
And please specify which PECL/memcache version you're using.

<?php
function user_error_handler( $severity, $msg, $filename, $linenum ) {
	print_r(debug_backtrace());
}
set_error_handler( 'user_error_handler' ); trigger_error( 'TEST', E_USER_WARNING );
$memcache_profile['name'] = 'production';
$memcache_profile['servers'][0]['host'] = 'mem1';		$memcache_profile['servers'][0]['port'] = 11211;
$memcache_profile['servers'][1]['host'] = 'error_test';	$memcache_profile['servers'][1]['port'] = 11211;
class memcached {
	var $memcache;	var $profile;
	function memcached($profile) {
		$this->profile	= $profile;	$this->memcache = new Memcache;
		foreach($profile['servers'] as $servers) $this->memcache->addServer($servers['host'], $servers['port'], 0, 10, 1, 20, true, array('memcached', 'raise_error'));
	}
	function get($key) { return $this->memcache->get($key);	}
	function set($key, $var, $expire = 0) {	return $this->memcache->set($key, $var, MEMCACHE_COMPRESSED, $expire);}
	function raise_error($host, $port) { trigger_error( "MEMCACHE: Server error. Profile: '{$this->profile['name']}' Host: '$host' Port: '$port'", E_USER_WARNING ); }
}
$memcache = &new memcached( $memcache_profile ); $memcache->set( 'key1', 'test key 1' ); $memcache->set( 'key2', 'test key 2' ); echo $memcache->get( 'key2' );
?>

Sorry, I forgot the PECL memcache version: 2.1.0

What are the actual and expected results of this code?

Sorry, I'll edit the issue again.

OK, I'try it again...

Description:
------------
Incompatibility detected when one
"failure callback" method is used inside the addServer() method.

The static call is OK, but not bypassing the real object. This really
works on another places!

Reproduce code:
---------------
<?php
$memcache_profile['name'] = 'production';
$memcache_profile['servers'][0]['host'] = 'mem1'; $memcache_profile['servers'][0]['port'] = 11211;
$memcache_profile['servers'][1]['host'] = 'error_test'; $memcache_profile['servers'][1]['port'] = 11211;
class memcached {
	var $memcache;
	var $profile;
	function memcached($profile) {
		$this->profile	= $profile; $this->memcache = new Memcache;
		foreach($profile['servers'] as $servers) $this->memcache->addServer($servers['host'], $servers['port'], 0, 10, 1, 20, true, array(&$this, 'raise_error'));
	}
	function get($key) { return $this->memcache->get($key); }
	function set($key, $var, $expire = 0) { return $this->memcache->set($key, $var, MEMCACHE_COMPRESSED, $expire); }
	function raise_error($host, $port) { trigger_error( "MEMCACHE: Server error. Profile: '{$this->profile['name']}' Host: '$host' Port: '$port'", E_USER_WARNING ); }
}
trigger_error( 'TEST', E_USER_WARNING );
$memcache = &new memcached( $memcache_profile ); $memcache->set( 'key1', 'test key 1' ); $memcache->set( 'key2', 'test key 2' ); echo $memcache->get( 'key2' );
?>

Expected:
--------

Warning: TEST in /home/basilio.vera/test/test_error_memcache.php on line 16

Warning: set(): php_network_getaddresses: getaddrinfo failed: Temporary failure in name resolution in /home/basilio.vera/test/test_error_memcache.php on line 13

Warning: MEMCACHE: Server error. Profile: 'production' Host: 'error_test' Port: '11211' in /home/basilio.vera/test/test_error_memcache.php on line 14
test key 2

Actual result:
-------------
NOTHING!!!

But if I change the addServer method from this: -> array(&$this, 'raise_error')

$this->memcache->addServer($servers['host'], $servers['port'], 0, 10, 1,
20, true, array(&$this, 'raise_error'));

to this -> array('memcached', 'raise_error') [called statically]

$this->memcache->addServer($servers['host'], $servers['port'], 0, 10, 1,
20, true, array('memcached', 'raise_error'));

I get:


Warning: TEST in /home/basilio.vera/test/test_error_memcache.php on line 16

Warning: set(): php_network_getaddresses: getaddrinfo failed: Temporary failure in name resolution in /home/basilio.vera/test/test_error_memcache.php on line 13

Warning: MEMCACHE: Server error. Profile: '' Host: 'error_test' Port: '11211' in /home/basilio.vera/test/test_error_memcache.php on line 14
test key 2

Your code is not going to work as is.
Using $this as the callback means adding a reference to $this to $this->memcache.
So you have the eternal chicken-and-egg problem here:
$this => $this->memcache => $this.
Don't do that.

The segfault should be fixed in CVS, though.

Also please, next time don't reduce the code removing new lines =)
It doesn't become shorter, but becomes completely unreadable. 50% of your reproduce code can be safely dropped in order to prepare really short reproduce code.