Support named arguments when resolving template parameters

src/Reflection/GenericParametersAcceptorResolver.php

@@ -12,7 +12,7 @@ class GenericParametersAcceptorResolver
 
 	/**
 	 * @api
-	 * @param Type[] $argTypes
+	 * @param array<int|string, Type> $argTypes
 	 */
 	public static function resolve(array $argTypes, ParametersAcceptor $parametersAcceptor): ParametersAcceptor
 	{
@@ -21,6 +21,8 @@ public static function resolve(array $argTypes, ParametersAcceptor $parametersAc
 		foreach ($parametersAcceptor->getParameters() as $i => $param) {
 			if (isset($argTypes[$i])) {
 				$argType = $argTypes[$i];
+			} elseif (isset($argTypes[$param->getName()])) {
+				$argType = $argTypes[$param->getName()];
 			} elseif ($param->getDefaultValue() !== null) {
 				$argType = $param->getDefaultValue();
 			} else {

src/Reflection/ParametersAcceptorSelector.php

@@ -18,6 +18,7 @@
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\UnionType;
+use function array_key_last;
 use function array_slice;
 use function count;
 use function sprintf;
@@ -161,21 +162,22 @@ public static function selectFromArgs(
 			}
 		}
 
-		foreach ($args as $arg) {
+		foreach ($args as $i => $arg) {
 			$type = $scope->getType($arg->value);
+			$index = $arg->name !== null ? $arg->name->toString() : $i;
 			if ($arg->unpack) {
 				$unpack = true;
-				$types[] = $type->getIterableValueType();
+				$types[$index] = $type->getIterableValueType();
 			} else {
-				$types[] = $type;
+				$types[$index] = $type;
 			}
 		}
 
 		return self::selectFromTypes($types, $parametersAcceptors, $unpack);
 	}
 
 	/**
-	 * @param Type[] $types
+	 * @param array<int|string, Type> $types
 	 * @param ParametersAcceptor[] $parametersAcceptors
 	 */
 	public static function selectFromTypes(
@@ -246,7 +248,7 @@ public static function selectFromTypes(
 						break;
 					}
 
-					$type = $types[count($types) - 1];
+					$type = $types[array_key_last($types)];
 				} else {
 					$type = $types[$i];
 				}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -846,6 +846,11 @@ public function dataFileAsserts(): iterable
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6917.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6936-limit.php');
+
+		if (PHP_VERSION_ID >= 80000) {
+			yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5262.php');
+		}
+
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6927.php');
 	}
 

tests/PHPStan/Analyser/data/bug-5262.php

@@ -0,0 +1,36 @@
+<?php declare(strict_types = 1);
+
+namespace Bug5262;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template T of TestBase
+ * @param class-string<T> $testclass
+ * @return T
+ */
+function test(bool $optional = false, string $testclass = TestBase::class): TestBase
+{
+	return new $testclass();
+}
+
+class TestBase
+{
+}
+
+class TestChild extends TestBase
+{
+	public function hello(): string
+	{
+		return 'world';
+	}
+}
+
+function runTest(): void
+{
+	assertType('Bug5262\TestChild', test(false, TestChild::class));
+	assertType('Bug5262\TestChild', test(false, testclass: TestChild::class));
+	assertType('Bug5262\TestChild', test(optional: false, testclass: TestChild::class));
+	assertType('Bug5262\TestChild', test(testclass: TestChild::class, optional: false));
+	assertType('Bug5262\TestChild', test(testclass: TestChild::class));
+}