Merge pull request #8249 from someniatko/issue-8200

Improve inferring the "final" `static` type when calling static methods inside a different class

src/Psalm/Internal/Analyzer/Statements/Expression/Call/StaticMethod/ExistingAtomicStaticCallAnalyzer.php

@@ -551,6 +551,14 @@ private static function getMethodReturnType(
             ) {
                 $static_type = $context->self;
                 $context_final = $codebase->classlike_storage_provider->get($context->self)->final;
+            } elseif ($context->calling_method_id !== null) {
+                // differentiate between these cases:
+                //   1. "static" comes from the CALLED static method - use $fq_class_name.
+                //   2. "static" in return type comes from return type of the
+                //   method CALLING the currently analyzed static method - use $context->self.
+                $static_type = self::hasStaticInType($return_type_candidate)
+                    ? $fq_class_name
+                    : $context->self;
             } else {
                 $static_type = $fq_class_name;
             }
@@ -613,4 +621,22 @@ private static function getMethodReturnType(
 
         return $return_type_candidate;
     }
+
+    /**
+     * Dumb way to determine whether a type contains "static" somewhere inside.
+     */
+    private static function hasStaticInType(Type\TypeNode $type): bool
+    {
+        if ($type instanceof TNamedObject && $type->value === 'static') {
+            return true;
+        }
+
+        foreach ($type->getChildNodes() as $child_type) {
+            if (self::hasStaticInType($child_type)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }

tests/Template/ClassTemplateTest.php

@@ -3694,6 +3694,111 @@ protected function setUp(): void
                         }
                     }',
             ],
+            'return TemplatedClass<static>' => [
+                '<?php
+
+                    /**
+                     * @template-covariant A
+                     * @psalm-immutable
+                     */
+                    final class Maybe
+                    {
+                        /**
+                         * @param null|A $value
+                         */
+                        public function __construct(private $value = null) {}
+
+                        /**
+                         * @template B
+                         * @param B $value
+                         * @return Maybe<B>
+                         *
+                         * @psalm-pure
+                         */
+                        public static function just($value): self
+                        {
+                            return new self($value);
+                        }
+                    }
+
+                    abstract class Test
+                    {
+                        final private function __construct() {}
+
+                        /** @return Maybe<static> */
+                        final public static function create(): Maybe
+                        {
+                            return Maybe::just(new static());
+                        }
+                    }',
+            ],
+            'return list<static> created in a static method of another class' => [
+                '<?php
+
+                    final class Lister
+                    {
+                        /**
+                         * @template B
+                         * @param B $value
+                         * @return list<B>
+                         *
+                         * @psalm-pure
+                         */
+                        public static function mklist($value): array
+                        {
+                            return [ $value ];
+                        }
+                    }
+
+                    abstract class Test
+                    {
+                        final private function __construct() {}
+
+                        /** @return list<static> */
+                        final public static function create(): array
+                        {
+                            return Lister::mklist(new static());
+                        }
+                    }',
+            ],
+            'use TemplatedClass<static> as an intermediate variable inside a method' => [
+                '<?php
+
+                    /**
+                     * @template-covariant A
+                     * @psalm-immutable
+                     */
+                    final class Maybe
+                    {
+                        /**
+                         * @param A $value
+                         */
+                        public function __construct(public $value) {}
+
+                        /**
+                         * @template B
+                         * @param B $value
+                         * @return Maybe<B>
+                         *
+                         * @psalm-pure
+                         */
+                        public static function just($value): self
+                        {
+                            return new self($value);
+                        }
+                    }
+
+                    abstract class Test
+                    {
+                        final private function __construct() {}
+
+                        final public static function create(): static
+                        {
+                            $maybe = Maybe::just(new static());
+                            return $maybe->value;
+                        }
+                    }',
+            ],
         ];
     }