Support intersection types in template bounds

Closes phpstan/phpstan#6649

Author: rvanvelzen

src/Rules/Generics/TemplateTypeCheck.php

@@ -18,6 +18,7 @@
 use PHPStan\Type\Generic\TemplateType;
 use PHPStan\Type\Generic\TemplateTypeScope;
 use PHPStan\Type\IntegerType;
+use PHPStan\Type\IntersectionType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\ObjectWithoutClassType;
@@ -107,6 +108,7 @@ public function check(
 				&& $boundTypeClass !== ObjectType::class
 				&& $boundTypeClass !== GenericObjectType::class
 				&& !$boundType instanceof UnionType
+				&& !$boundType instanceof IntersectionType
 				&& !$boundType instanceof TemplateType
 			) {
 				$messages[] = RuleErrorBuilder::message(sprintf($notSupportedBoundMessage, $templateTagName, $boundType->describe(VerbosityLevel::typeOnly())))->build();

src/Type/Generic/TemplateIntersectionType.php

@@ -0,0 +1,48 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Generic;
+
+use PHPStan\Type\IntersectionType;
+use PHPStan\Type\Type;
+
+/** @api */
+final class TemplateIntersectionType extends IntersectionType implements TemplateType
+{
+
+	/** @use TemplateTypeTrait<IntersectionType> */
+	use TemplateTypeTrait;
+
+	public function __construct(
+		TemplateTypeScope $scope,
+		TemplateTypeStrategy $templateTypeStrategy,
+		TemplateTypeVariance $templateTypeVariance,
+		string $name,
+		IntersectionType $bound,
+	)
+	{
+		parent::__construct($bound->getTypes());
+
+		$this->scope = $scope;
+		$this->strategy = $templateTypeStrategy;
+		$this->variance = $templateTypeVariance;
+		$this->name = $name;
+		$this->bound = $bound;
+	}
+
+	public function traverse(callable $cb): Type
+	{
+		$newBound = $cb($this->getBound());
+		if ($this->getBound() !== $newBound && $newBound instanceof IntersectionType) {
+			return new self(
+				$this->scope,
+				$this->strategy,
+				$this->variance,
+				$this->name,
+				$newBound,
+			);
+		}
+
+		return $this;
+	}
+
+}

src/Type/Generic/TemplateTypeFactory.php

@@ -9,6 +9,7 @@
 use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\FloatType;
 use PHPStan\Type\IntegerType;
+use PHPStan\Type\IntersectionType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\ObjectWithoutClassType;
@@ -79,6 +80,10 @@ public static function create(TemplateTypeScope $scope, string $name, ?Type $bou
 			}
 		}
 
+		if ($bound instanceof IntersectionType) {
+			return new TemplateIntersectionType($scope, $strategy, $variance, $name, $bound);
+		}
+
 		return new TemplateMixedType($scope, $strategy, $variance, $name, new MixedType(true));
 	}
 

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -601,6 +601,12 @@ public function testBug6866(): void
 		$this->assertNoErrors($errors);
 	}
 
+	public function testBug6649(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-6649.php');
+		$this->assertNoErrors($errors);
+	}
+
 	/**
 	 * @param string[]|null $allAnalysedFiles
 	 * @return Error[]

tests/PHPStan/Analyser/data/bug-6649.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace Bug6649;
+
+use function PHPStan\Testing\assertType;
+
+class Foo {}
+interface Bar {}
+
+class FooBar extends Foo implements Bar {}
+
+/**
+ * @template TKey of Foo
+ */
+class Collection {}
+
+/**
+ * @template TKey of Foo&Bar
+ * @extends Collection<TKey>
+ */
+class SubCollection extends Collection {
+    /** @param TKey $key */
+	public function __construct($key) {
+		assertType('TKey of Bug6649\Bar&Bug6649\Foo (class Bug6649\SubCollection, argument)', $key);
+	}
+
+	public static function test(): void {
+		assertType('Bug6649\SubCollection<Bug6649\FooBar>', new SubCollection(new FooBar()));
+	}
+}