Support iterable as template type

Fixes phpstan/phpstan#12214

Author: RobertMe

src/Rules/Generics/TemplateTypeCheck.php

@@ -22,6 +22,7 @@
 use PHPStan\Type\Generic\TemplateTypeScope;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\IntersectionType;
+use PHPStan\Type\IterableType;
 use PHPStan\Type\KeyOfType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\ObjectShapeType;
@@ -123,6 +124,7 @@ public function check(
 				&& $boundTypeClass !== ObjectShapeType::class
 				&& $boundTypeClass !== GenericObjectType::class
 				&& $boundTypeClass !== KeyOfType::class
+				&& $boundTypeClass !== IterableType::class
 				&& !$boundType instanceof UnionType
 				&& !$boundType instanceof IntersectionType
 				&& !$boundType instanceof TemplateType

src/Type/Generic/TemplateIterableType.php

@@ -0,0 +1,38 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Generic;
+
+use PHPStan\Type\IterableType;
+use PHPStan\Type\Traits\UndecidedComparisonCompoundTypeTrait;
+use PHPStan\Type\Type;
+
+/** @api */
+final class TemplateIterableType extends IterableType implements TemplateType
+{
+
+	/** @use TemplateTypeTrait<IterableType> */
+	use TemplateTypeTrait;
+	use UndecidedComparisonCompoundTypeTrait;
+
+	/**
+	 * @param non-empty-string $name
+	 */
+	public function __construct(
+		TemplateTypeScope $scope,
+		TemplateTypeStrategy $templateTypeStrategy,
+		TemplateTypeVariance $templateTypeVariance,
+		string $name,
+		IterableType $bound,
+		?Type $default,
+	)
+	{
+		parent::__construct($bound->getKeyType(), $bound->getItemType());
+		$this->scope = $scope;
+		$this->strategy = $templateTypeStrategy;
+		$this->variance = $templateTypeVariance;
+		$this->name = $name;
+		$this->bound = $bound;
+		$this->default = $default;
+	}
+
+}

src/Type/Generic/TemplateTypeFactory.php

@@ -12,6 +12,7 @@
 use PHPStan\Type\FloatType;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\IntersectionType;
+use PHPStan\Type\IterableType;
 use PHPStan\Type\KeyOfType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\ObjectShapeType;
@@ -107,6 +108,10 @@ public static function create(TemplateTypeScope $scope, string $name, ?Type $bou
 			return new TemplateKeyOfType($scope, $strategy, $variance, $name, $bound, $default);
 		}
 
+		if ($bound instanceof IterableType && ($boundClass === IterableType::class || $bound instanceof TemplateType)) {
+			return new TemplateIterableType($scope, $strategy, $variance, $name, $bound, $default);
+		}
+
 		return new TemplateMixedType($scope, $strategy, $variance, $name, new MixedType(true), $default);
 	}
 

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -1481,6 +1481,12 @@ public function testBug11913(): void
 		$this->assertNoErrors($errors);
 	}
 
+	public function testBug12214(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-12214.php');
+		$this->assertNoErrors($errors);
+	}
+
 	/**
 	 * @param string[]|null $allAnalysedFiles
 	 * @return Error[]

tests/PHPStan/Analyser/data/bug-12214.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Bug12214;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param iterable<array-key, mixed> $test
+ */
+function test_iterable(iterable $test): void
+{
+	assertType('iterable<(int|string), mixed>', $test);
+}
+
+/**
+ * @template T of array<array-key, mixed>
+ * @param T $test
+ */
+function test_array(array $test): void
+{
+	assertType('T of array (function Bug12214\test_array(), argument)', $test);
+}
+
+/**
+ * @template T of iterable<array-key, mixed>
+ * @param T $test
+ */
+function test_generic_iterable(iterable $test): void
+{
+	assertType('T of iterable<(int|string), mixed> (function Bug12214\test_generic_iterable(), argument)', $test);
+}