Type hint array reduce closure

rules-tests/TypeDeclaration/Rector/FunctionLike/AddClosureParamTypeForArrayReduceRector/AddClosureParamTypeForArrayReduceRectorTest.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayReduceRector;
+
+use Iterator;
+use PHPUnit\Framework\Attributes\DataProvider;
+use Rector\Testing\PHPUnit\AbstractRectorTestCase;
+
+final class AddClosureParamTypeForArrayReduceRectorTest extends AbstractRectorTestCase
+{
+    #[DataProvider('provideData')]
+    public function test(string $filePath): void
+    {
+        $this->doTestFile($filePath);
+    }
+
+    public static function provideData(): Iterator
+    {
+        return self::yieldFilesFromDirectory(__DIR__ . '/Fixture');
+    }
+
+    public function provideConfigFilePath(): string
+    {
+        return __DIR__ . '/config/configured_rule.php';
+    }
+}

rules-tests/TypeDeclaration/Rector/FunctionLike/AddClosureParamTypeForArrayReduceRector/Fixture/fixture.php.inc

@@ -0,0 +1,57 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayReduceRector\Fixture;
+
+class Fixture
+{
+    /**
+     * @param list<string> $array
+     */
+    public function run(array $array)
+    {
+        return array_reduce($array, function ($carry, $value) {
+            return $carry . $value;
+        }, '');
+    }
+
+    /**
+     * @param list<string|int> $array
+     */
+    public function runTwo(array $array)
+    {
+        return array_reduce($array, function ($carry, $value) {
+            return $carry . $value;
+        }, 100);
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayReduceRector\Fixture;
+
+class Fixture
+{
+    /**
+     * @param list<string> $array
+     */
+    public function run(array $array)
+    {
+        return array_reduce($array, function (string $carry, string $value) {
+            return $carry . $value;
+        }, '');
+    }
+
+    /**
+     * @param list<string|int> $array
+     */
+    public function runTwo(array $array)
+    {
+        return array_reduce($array, function (int|string $carry, int|string $value) {
+            return $carry . $value;
+        }, 100);
+    }
+}
+
+?>

rules-tests/TypeDeclaration/Rector/FunctionLike/AddClosureParamTypeForArrayReduceRector/Fixture/skip_mixed_type.php.inc

@@ -0,0 +1,28 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayReduceRector\Fixture;
+
+class SkipMixedType
+{
+    /**
+     * @param array<int, mixed> $array
+     */
+    public function run(array $array)
+    {
+        return array_reduce($array, function ($carry, $value) {
+            return $value->foo($carry);
+        }, '');
+    }
+
+    /**
+     * @param array<int, mixed> $array
+     */
+    public function runTwo(array $array, mixed $initial)
+    {
+        return array_reduce($array, function ($carry, $value) {
+            return '';
+        }, $initial);
+    }
+}
+
+?>

rules-tests/TypeDeclaration/Rector/FunctionLike/AddClosureParamTypeForArrayReduceRector/Fixture/skip_non_array_reduce_functions.php.inc

@@ -0,0 +1,23 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayMapRector\Fixture;
+
+function array_reduce(array $array, callable $func, $initial = null): array
+{
+
+}
+
+class SkipNonArrayReduceFunctions
+{
+    /**
+     * @param array<int, string> $array
+     */
+    public function run(array $array)
+    {
+        return \Rector\Tests\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayMapRector\Fixture\array_reduce($array, function ($value, $key) {
+            return $value . $key;
+        });
+    }
+}
+
+?>

rules-tests/TypeDeclaration/Rector/FunctionLike/AddClosureParamTypeForArrayReduceRector/config/configured_rule.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+use Rector\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayReduceRector;
+use Rector\ValueObject\PhpVersionFeature;
+
+return static function (RectorConfig $rectorConfig): void {
+    $rectorConfig
+        ->rules([AddClosureParamTypeForArrayReduceRector::class]);
+
+    $rectorConfig->phpVersion(PhpVersionFeature::UNION_TYPES);
+};

rules/TypeDeclaration/Rector/FunctionLike/AddClosureParamTypeForArrayReduceRector.php

@@ -0,0 +1,185 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\TypeDeclaration\Rector\FunctionLike;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\Closure;
+use PhpParser\Node\Expr\FuncCall;
+use PhpParser\Node\Param;
+use PHPStan\Reflection\Native\NativeFunctionReflection;
+use PHPStan\Type\ClosureType;
+use PHPStan\Type\MixedType;
+use PHPStan\Type\Type;
+use PHPStan\Type\UnionType;
+use PHPStan\Type\UnionTypeHelper;
+use Rector\NodeTypeResolver\TypeComparator\TypeComparator;
+use Rector\PHPStanStaticTypeMapper\Enum\TypeKind;
+use Rector\Rector\AbstractRector;
+use Rector\Reflection\ReflectionResolver;
+use Rector\StaticTypeMapper\StaticTypeMapper;
+use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
+use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;
+
+/**
+ * @see \Rector\Tests\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayReduceRector\AddClosureParamTypeForArrayReduceRectorTest
+ */
+final class AddClosureParamTypeForArrayReduceRector extends AbstractRector
+{
+    public function __construct(
+        private readonly TypeComparator $typeComparator,
+        private readonly StaticTypeMapper $staticTypeMapper,
+        private readonly ReflectionResolver $reflectionResolver,
+    ) {
+    }
+
+    public function getRuleDefinition(): RuleDefinition
+    {
+        return new RuleDefinition(
+            'Applies type hints to array_map closures',
+            [
+                new CodeSample(
+                    <<<'CODE_SAMPLE'
+array_reduce($strings, function ($carry, $value, $key): string {
+    return $carry . $value;
+}, $initialString);
+CODE_SAMPLE
+                    ,
+                    <<<'CODE_SAMPLE'
+array_reduce($strings, function (string $carry, string $value): string {
+    return $carry . $value;
+}, $initialString);
+CODE_SAMPLE
+                    ,
+                ),
+            ]
+        );
+    }
+
+    public function getNodeTypes(): array
+    {
+        return [FuncCall::class];
+    }
+
+    /**
+     * @param FuncCall $node
+     */
+    public function refactor(Node $node): ?Node
+    {
+        if ($node->isFirstClassCallable()) {
+            return null;
+        }
+
+        if (! $this->isName($node, 'array_reduce')) {
+            return null;
+        }
+
+        $funcReflection = $this->reflectionResolver->resolveFunctionLikeReflectionFromCall($node);
+
+        if (! $funcReflection instanceof NativeFunctionReflection) {
+            return null;
+        }
+
+        $args = $node->getArgs();
+
+        if (! isset($args[1]) || ! $args[1]->value instanceof Closure) {
+            return null;
+        }
+
+        $closureType = $this->getType($args[1]->value);
+        if (! $closureType instanceof ClosureType) {
+            return null;
+        }
+
+        $carryType = $closureType->getReturnType();
+
+        if (isset($args[2])) {
+            $carryType = $this->combineTypes([$this->getType($args[2]->value), $carryType]);
+        }
+
+        $type = $this->getType($args[0]->value);
+        $valueType = $type->getIterableValueType();
+
+        if ($this->updateClosureWithTypes($args[1]->value, $valueType, $carryType)) {
+            return $node;
+        }
+
+        return null;
+    }
+
+    private function updateClosureWithTypes(Closure $closure, ?Type $valueType, ?Type $carryType): bool
+    {
+        $changes = false;
+        $carryParam = $closure->params[0] ?? null;
+        $valueParam = $closure->params[1] ?? null;
+
+        if ($valueParam instanceof Param && $valueType instanceof Type && $this->refactorParameter(
+            $valueParam,
+            $valueType
+        )) {
+            $changes = true;
+        }
+
+        if ($carryParam instanceof Param && $carryType instanceof Type && $this->refactorParameter(
+            $carryParam,
+            $carryType
+        )) {
+            return true;
+        }
+
+        return $changes;
+    }
+
+    private function refactorParameter(Param $param, Type $type): bool
+    {
+        if ($type instanceof MixedType) {
+            return false;
+        }
+
+        // already set → no change
+        if ($param->type instanceof Node) {
+            $currentParamType = $this->staticTypeMapper->mapPhpParserNodePHPStanType($param->type);
+            if ($this->typeComparator->areTypesEqual($currentParamType, $type)) {
+                return false;
+            }
+        }
+
+        $paramTypeNode = $this->staticTypeMapper->mapPHPStanTypeToPhpParserNode($type, TypeKind::PARAM);
+
+        if (! $paramTypeNode instanceof Node) {
+            return false;
+        }
+
+        $param->type = $paramTypeNode;
+
+        return true;
+    }
+
+    /**
+     * @param Type[] $types
+     */
+    private function combineTypes(array $types): ?Type
+    {
+        if ($types === []) {
+            return null;
+        }
+
+        $types = array_reduce($types, function (array $types, Type $type): array {
+            foreach ($types as $previousType) {
+                if ($this->typeComparator->areTypesEqual($type, $previousType)) {
+                    return $types;
+                }
+            }
+
+            $types[] = $type;
+            return $types;
+        }, []);
+
+        if (count($types) === 1) {
+            return $types[0];
+        }
+
+        return new UnionType(UnionTypeHelper::sortTypes($types));
+    }
+}

src/Config/Level/TypeDeclarationLevel.php

@@ -49,6 +49,8 @@
 use Rector\TypeDeclaration\Rector\Closure\ClosureReturnTypeRector;
 use Rector\TypeDeclaration\Rector\Empty_\EmptyOnNullableObjectToInstanceOfRector;
 use Rector\TypeDeclaration\Rector\Function_\AddFunctionVoidReturnTypeWhereNoReturnRector;
+use Rector\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayMapRector;
+use Rector\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayReduceRector;
 use Rector\TypeDeclaration\Rector\FunctionLike\AddParamTypeSplFixedArrayRector;
 use Rector\TypeDeclaration\Rector\FunctionLike\AddReturnTypeDeclarationFromYieldsRector;
 use Rector\TypeDeclaration\Rector\Property\TypedPropertyFromAssignsRector;
@@ -120,6 +122,8 @@ final class TypeDeclarationLevel
         // closures
         AddClosureNeverReturnTypeRector::class,
         ClosureReturnTypeRector::class,
+        AddClosureParamTypeForArrayReduceRector::class,
+        AddClosureParamTypeForArrayMapRector::class,
 
         // more risky rules
         ReturnTypeFromStrictParamRector::class,