Issue #3143173 by martin107, andypost, longwave: Followup: ProxyBuilder...

Issue #3143173 by martin107, andypost, longwave: Followup: ProxyBuilder compatibility with Symfony 5  - needs to handle voids correctly

core/lib/Drupal/Component/ProxyBuilder/ProxyBuilder.php

@@ -300,7 +300,12 @@ protected function buildMethodBody(\ReflectionMethod $reflection_method) {
     $function_name = $reflection_method->getName();
 
     if (!$reflection_method->isStatic()) {
-      $output .= '    return $this->lazyLoadItself()->' . $function_name . '(';
+      if ($reflection_method->getReturnType() && $reflection_method->getReturnType()->getName() === 'void') {
+        $output .= '    $this->lazyLoadItself()->' . $function_name . '(';
+      }
+      else {
+        $output .= '    return $this->lazyLoadItself()->' . $function_name . '(';
+      }
     }
     else {
       $class_name = $reflection_method->getDeclaringClass()->getName();

core/tests/Drupal/Tests/Component/ProxyBuilder/ProxyBuilderTest.php

@@ -139,6 +139,30 @@ public function complexMethod(string $parameter, callable $function, \Drupal\Tes
     return $this->lazyLoadItself()->complexMethod($parameter, $function, $test_service, $elements);
 }
 
+EOS;
+
+    $this->assertEquals($this->buildExpectedClass($class, $method_body), $result);
+  }
+
+  /**
+   * @covers ::buildMethodBody
+   */
+  public function testBuildServiceMethodReturnsVoid() {
+    $class = TestServiceMethodReturnsVoid::class;
+
+    $result = $this->proxyBuilder->build($class);
+
+    // @todo Solve the silly linebreak for array()
+    $method_body = <<<'EOS'
+
+/**
+ * {@inheritdoc}
+ */
+public function methodReturnsVoid(string $parameter): void
+{
+    $this->lazyLoadItself()->methodReturnsVoid($parameter);
+}
+
 EOS;
 
     $this->assertEquals($this->buildExpectedClass($class, $method_body), $result);
@@ -387,6 +411,14 @@ public function complexMethod(string $parameter, callable $function, TestService
 
 }
 
+class TestServiceMethodReturnsVoid {
+
+  public function methodReturnsVoid(string $parameter): void {
+
+  }
+
+}
+
 class TestServiceReturnReference {
 
   public function &returnReference() {