Merge branch '4.3' into 4

src/Core/Extensible.php

@@ -388,6 +388,10 @@ trait Extensible
             if (!$strict && is_subclass_of($extension, $requiredExtension)) {
                 return true;
             }
+            $inst = Injector::inst()->get($extension);
+            if ($inst instanceof $requiredExtension) {
+                return $strict ? strcasecmp(get_class($inst), $requiredExtension) === 0 : true;
+            }
         }
 
         return false;

tests/php/Core/ObjectTest.php

@@ -11,6 +11,7 @@ use SilverStripe\Core\Tests\ObjectTest\ExtendTest1;
 use SilverStripe\Core\Tests\ObjectTest\ExtendTest2;
 use SilverStripe\Core\Tests\ObjectTest\ExtendTest3;
 use SilverStripe\Core\Tests\ObjectTest\ExtendTest4;
+use SilverStripe\Core\Tests\ObjectTest\ExtendTest5;
 use SilverStripe\Core\Tests\ObjectTest\ExtensionRemoveTest;
 use SilverStripe\Core\Tests\ObjectTest\ExtensionTest;
 use SilverStripe\Core\Tests\ObjectTest\ExtensionTest2;
@@ -290,6 +291,13 @@ class ObjectTest extends SapphireTest
             "Extensions are detected with instance hasExtension() when added through add_extension()"
         );
         
+        // load in a custom implementation
+        Injector::inst()->registerService(new ExtendTest5(), ExtendTest4::class);
+        $this->assertTrue(
+            ExtensionTest3::has_extension(ExtendTest5::class),
+            "Injected sub-extensions are detected with static has_extension() when added through add_extension()"
+        );
+
         // @todo At the moment, this does NOT remove the extension due to parameterized naming,
         //  meaning the extension will remain added in further test cases
         ExtensionTest::remove_extension(ExtendTest3::class);

tests/php/Core/ObjectTest/ExtendTest5.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace SilverStripe\Core\Tests\ObjectTest;
+
+class ExtendTest5 extends ExtendTest4
+{
+    public function extendableMethod($argument = null)
+    {
+        return "ExtendTest5($argument)";
+    }
+}