Proper nullsafe call chain support (#46)

Author: janedbal

src/Collector/MethodCallCollector.php

@@ -21,6 +21,7 @@
 use PHPStan\Reflection\ClassReflection;
 use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use ShipMonk\PHPStan\DeadCode\Helper\DeadCodeHelper;
 
 /**
@@ -200,7 +201,9 @@ private function getMethodName(CallLike $call): ?string
      */
     private function getReflectionsWithMethod(Type $type, string $methodName): iterable
     {
-        $classReflections = $type->getObjectTypeOrClassStringObjectType()->getObjectClassReflections();
+        // remove null to support nullsafe calls
+        $typeNoNull = TypeCombinator::removeNull($type);
+        $classReflections = $typeNoNull->getObjectTypeOrClassStringObjectType()->getObjectClassReflections();
 
         foreach ($classReflections as $classReflection) {
             if ($classReflection->hasMethod($methodName)) {

tests/Rule/DeadMethodRuleTest.php

@@ -87,6 +87,7 @@ public static function provideFiles(): iterable
         yield 'trait-1' => [__DIR__ . '/data/DeadMethodRule/traits-1.php'];
         yield 'trait-2' => [__DIR__ . '/data/DeadMethodRule/traits-2.php'];
         yield 'trait-3' => [__DIR__ . '/data/DeadMethodRule/traits-3.php'];
+        yield 'nullsafe' => [__DIR__ . '/data/DeadMethodRule/nullsafe.php'];
         yield 'dead-in-parent-1' => [__DIR__ . '/data/DeadMethodRule/dead-in-parent-1.php'];
         yield 'indirect-interface' => [__DIR__ . '/data/DeadMethodRule/indirect-interface.php'];
         yield 'attribute' => [__DIR__ . '/data/DeadMethodRule/attribute.php'];

tests/Rule/data/DeadMethodRule/nullsafe.php

@@ -0,0 +1,29 @@
+<?php declare(strict_types = 1);
+
+namespace Nullsafe;
+
+class A {
+
+    public function first(): self {
+        return $this;
+    }
+
+    public function second(): self {
+        return $this;
+    }
+
+    public static function secondStatic(): self {
+        return new self();
+    }
+}
+
+class B {
+
+    public function test(?A $a): void
+    {
+        $a?->first()->second();
+        $a?->first()::secondStatic();
+    }
+}
+
+(new B())->test(null);