Possibly a duplicate of bug #69629.

Here's a self-contained and somewhat reduced reproduce script. It seems to be important that the last class is defined in a separate file:

<?php

namespace Provider;

interface Iface {}

abstract class Base {
    public function __construct(
        \Aimeos\MShop\Context\Item\Iface $context, \Item\Iface $serviceItem
    ) { }
}

namespace Provider\Factory;

interface Iface {
    public function __construct(
        \Aimeos\MShop\Context\Item\Iface $context, \Item\Iface $serviceItem);
}

namespace Provider\Delivery;

interface Iface extends
    \Provider\Iface, \Provider\Factory\Iface { }

abstract class Base extends \Provider\Base { }

class Manual
	extends \Provider\Delivery\Base
	implements \Provider\Delivery\Iface
{ }

namespace Provider\Decorator;

interface Iface
	extends \Provider\Iface
{
    public function __construct(\Provider\Iface $provider, $context, \Item\Iface $serviceItem);
}

$code = <<<'PHP'
namespace Provider\Decorator;

abstract class Base
	extends \Provider\Base
{
	public function __construct(\Provider\Iface $provider, $context, \Item\Iface $serviceItem) { }
}
PHP;
eval($code);

Ooops, I pasted the non-reduced code. Here's the correct version:

<?php

namespace Provider;

interface Iface { }

abstract class Base {
    public function __construct(\Item\Iface $serviceItem) { }
}

namespace Provider\Factory;

interface Iface {
    public function __construct(\Item\Iface $serviceItem);
}

namespace Provider\Delivery;

interface Iface extends \Provider\Iface, \Provider\Factory\Iface { }

abstract class Base extends \Provider\Base { }

class Manual extends \Provider\Delivery\Base implements \Provider\Delivery\Iface { }

$code = <<<'PHP'
namespace Provider\Decorator;

abstract class Base extends \Provider\Base {
    public function __construct(\Provider\Iface $provider, \Item\Iface $serviceItem) { }
}
PHP;
eval($code);

The problem is that in PHP 7 we will share the op_array between inherited class methods if it does not use static variables, under the assumption that all their members will stay the same.

However this assumption is not true in this case, namely function->common.prototype may differ. In this case Provider\Base::__construct() has no prototype, while Provider\Delivery\Manual::__construct() [inherited from Provider\Base::__construct()] has Provider\Factory\Iface::__construct() as the prototype. As the op_array is shared between both this inheritance will clobber common.prototype for Provider\Base::__construct() as well. This then causes the inheritance error in Provider\Decorator\Base.

We could fix it by simply always using a separate op_array (i.e. drop http://lxr.php.net/xref/PHP_MASTER/Zend/zend_inheritance.c#77). Is there a better way to somehow only copy if we need a different prototype?

@dmitry: Regarding the last comment, do you see a better way to solve it, short of always copying the op_array struct during inheritance?

We should try to lazely duplicate op_array, only in case of op_array.prototype modification (copy on write).

This patch should fix the problem

https://gist.github.com/dstogov/81ded758484a608b831b

@nikic: please review.