Bug in DI generation: array arguments got replaced instead of merging when modified from different area

[ilnytskyi]

Preconditions (*)

1. Create a configurable object or virtual type e.g. composite
2. It's impossible to add new items into array argument for different area.
3. Related problem was reported here: https://stackoverflow.com/questions/34635615/magento-2-how-to-add-new-value-to-the-array-on-di-xml

Other should areas extend di configuration from global, or override only changed items/arguments. But in case with array arguments the DI compilation process overrides entire array instead of merging its items.

See the code in methods:

\Magento\Framework\ObjectManager\Config\Config::_mergeConfiguration L248
\Magento\Framework\ObjectManager\Config\Config::_collectConfiguration L210

the arguments will be replaced

Steps to reproduce (*)

1. Configure an object in global area

GLOBAL area di.xml
<virtualType name="SomeCompositeHandler" type="Magento\Payment\Gateway\Response\HandlerChain">
    <arguments>
        <argument name="handlers" xsi:type="array">
            <item name="some_handler_global" xsi:type="string">SomeHandlerGlobal</item>
        </argument>
    </arguments>
</virtualType>

2. Modify the object in adminhtml area

ADMINHTML area di.xml
<virtualType name="SomeCompositeHandler">
    <arguments>
        <argument name="handlers" xsi:type="array">
            <item name="some_handler_for_admin" xsi:type="string">SomeHandlerForAdmin</item>
        </argument>
    </arguments>
</virtualType>

Expected result (*)

1. The final object in code contains handlers from both areas as if it was defined like this in di.xml

Expected result for ADMINHTML area:
<virtualType name="SomeCompositeHandler">
    <arguments>
        <argument name="handlers" xsi:type="array">
            <item name="some_handler_global" xsi:type="string">SomeHandlerGlobal</item>
            <item name="some_handler_for_admin" xsi:type="string">SomeHandlerForAdmin</item>
        </argument>
    </arguments>
</virtualType>

Actual result (*)

1. The handlers array argument got overridden instead of merged and works only the way defined in admin.

Actual result for ADMINHTML area:
<virtualType name="SomeCompositeHandler">
    <arguments>
        <argument name="handlers" xsi:type="array">
            <item name="some_handler_for_admin" xsi:type="string">SomeHandlerForAdmin</item>
        </argument>
    </arguments>
</virtualType>

So global handler is lost.

WORKAROUND:

Add all missed arguments from global area if you want to add additional ones for target area.

Might be also related to:
#34394
#28193
#31468
#15042

The issue is applicable also for cases when we follow guides like this:
https://devdocs.magento.com/guides/v2.4/inventory/source-selection-algorithms.html#configure-dixml
But what is I want to add new algorithm that is available only in certain area? Then all other algorithms added by modules will be removed, it's unexpected behavior!!

---

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• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
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• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @ilnytskyi. Thank you for your report.
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[sezio]

Can confirm issue : I met the same problem with the graphql and the global area. Arguments were replaced.

[m2-assistant]

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[engcom-Hotel]

Hi @ilnytskyi

Thank you for reporting the issue.

We are able to reproduce it on Magento 2.4-develop

Steps followed to reproduce this issue.

• Create a custom module.

• Create a global area di.xml.
  

• Create di.xml in adminhtml area.
  

• Create respective classes defined in di.xml
  

And

Now use TestB class in any other class and set a breakpoint in Constructor.
This $testObject should contains 3 values in $stringData arguments of Test Class.

Thanks