Readme: improve AST-based usage provider example (#156)

Author: janedbal

README.md

@@ -129,32 +129,42 @@ services:
 use ReflectionMethod;
 use ShipMonk\PHPStan\DeadCode\Provider\ReflectionBasedMemberUsageProvider;
 
-class ApiOutputUsageProvider extends ReflectionBasedMemberUsageProvider
+class FuzzyTwigUsageProvider extends ReflectionBasedMemberUsageProvider
 {
 
     public function shouldMarkMethodAsUsed(ReflectionMethod $method): bool
     {
-        // all methods from our ApiOutput interface are called automatically (e.g. during serialization)
-        return $method->getDeclaringClass()->implementsInterface(ApiOutput::class);
+        return $method->getDeclaringClass()->implementsInterface(UsedInTwigMarkerInterface::class);
     }
 
 }
 ```
 
 ### AST-based customization:
-- For more complex usecases that are deducible only from AST (e.g. serialization calls), you just stick with raw `MemberUsageProvider` interface:
+- For more complex usecases that are deducible only from AST, you just stick with raw `MemberUsageProvider` interface.
+- Here is simplified example how to emit `User::__construct` usage in following PHP snippet:
 
 ```php
+function test(SerializerInterface $serializer): User {
+    return $serializer->deserialize('{"name": "John"}', User::class, 'json');
+}
+```
 
+```php
 use ReflectionMethod;
 use ShipMonk\PHPStan\DeadCode\Graph\ClassMethodRef;
 use ShipMonk\PHPStan\DeadCode\Graph\ClassMethodUsage;
+use ShipMonk\PHPStan\DeadCode\Graph\UsageOriginDetector;
 use ShipMonk\PHPStan\DeadCode\Provider\MemberUsageProvider;
 use Symfony\Component\Serializer\SerializerInterface;
 
 class DeserializationUsageProvider implements MemberUsageProvider
 {
 
+    public function __construct(
+        private UsageOriginDetector $originDetector,
+    ) {}
+
     /**
      * @return list<ClassMemberUsage>
      */
@@ -173,7 +183,7 @@ class DeserializationUsageProvider implements MemberUsageProvider
             $serializedClass = $scope->getType($secondArgument)->getConstantStrings()[0];
 
             // record the method it was called from (needed for proper transitive dead code elimination)
-            $originRef = $this->getOriginMethodRef($scope);
+            $originRef = $this->originDetector->detectOrigin($node, $scope);
 
             // record the hidden constructor call
             $constructorRef = new ClassMethodRef($serializedClass->getValue(), '__construct', false);
@@ -184,15 +194,6 @@ class DeserializationUsageProvider implements MemberUsageProvider
         return [];
     }
 
-    private function getOriginMethodRef(Scope $scope): ?ClassMethodRef
-    {
-        return new ClassMethodRef(
-            $scope->getClassReflection()->getName(),
-            $scope->getFunction()->getName(),
-            false,
-        );
-    }
-
 }
 ```