Docblock psudo methods can be inherited via @mixin

Fixes #3556

Author: robchett

src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MissingMethodCallHandler.php

@@ -435,6 +435,12 @@ private static function findPseudoMethodAndClassStorages(
         }
 
         $ancestors = $static_class_storage->class_implements;
+        foreach ($static_class_storage->namedMixins as $namedObject) {
+            $type = $namedObject->value;
+            if ($type) {
+                $ancestors[$type] = true;
+            }
+        }
 
         foreach ($ancestors as $fq_class_name => $_) {
             $class_storage = $codebase->classlikes->getStorageFor($fq_class_name);

tests/MixinAnnotationTest.php

@@ -596,6 +596,28 @@ class FooModel extends Model {}
                     '$g' => 'list<FooModel>',
                 ],
             ],
+            'mixinInheritMagicMethods' => [
+                'code' => '<?php
+                    /**
+                     * @method $this active()
+                     */
+                    class A {
+                        public function __call(string $name, array $arguments) {}
+                    }
+
+                    /**
+                     * @mixin A
+                     */
+                    class B {
+                        public function __call(string $name, array $arguments) {}
+                    }
+
+                    $b = new B;
+                    $c = $b->active();',
+                'assertions' => [
+                    '$c' => 'B',
+                ],
+            ],
         ];
     }