Add DatePeriod dynamic return type

conf/config.neon

@@ -22,7 +22,8 @@ parameters:
 	featureToggles:
 		bleedingEdge: false
 		disableRuntimeReflectionProvider: false
-		skipCheckGenericClasses: []
+		skipCheckGenericClasses:
+			- DatePeriod
 	fileExtensions:
 		- php
 	checkAdvancedIsset: false
@@ -1528,6 +1529,10 @@ services:
 		tags:
 			- phpstan.broker.dynamicMethodReturnTypeExtension
 
+	-
+		class: PHPStan\Type\Php\DatePeriodConstructorReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicStaticMethodReturnTypeExtension
 
 	exceptionTypeResolver:
 		class: PHPStan\Rules\Exceptions\ExceptionTypeResolver

src/Type/Php/DatePeriodConstructorReturnTypeExtension.php

@@ -0,0 +1,61 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use DatePeriod;
+use DateTimeInterface;
+use PhpParser\Node\Expr\StaticCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\Type\DynamicStaticMethodReturnTypeExtension;
+use PHPStan\Type\Generic\GenericObjectType;
+use PHPStan\Type\IntegerType;
+use PHPStan\Type\NullType;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\Type;
+
+class DatePeriodConstructorReturnTypeExtension implements DynamicStaticMethodReturnTypeExtension
+{
+
+	public function getClass(): string
+	{
+		return DatePeriod::class;
+	}
+
+	public function isStaticMethodSupported(MethodReflection $methodReflection): bool
+	{
+		return $methodReflection->getName() === '__construct';
+	}
+
+	public function getTypeFromStaticMethodCall(MethodReflection $methodReflection, StaticCall $methodCall, Scope $scope): Type
+	{
+		$thirdArgType = null;
+		if (isset($methodCall->getArgs()[2])) {
+			$thirdArgType = $scope->getType($methodCall->getArgs()[2]->value);
+		}
+
+		if (!$thirdArgType instanceof Type) {
+			return new GenericObjectType(DatePeriod::class, [
+				new NullType(),
+				new IntegerType(),
+			]);
+		}
+
+		if ((new ObjectType(DateTimeInterface::class))->isSuperTypeOf($thirdArgType)->yes()) {
+			return new GenericObjectType(DatePeriod::class, [
+				new ObjectType(DateTimeInterface::class),
+				new NullType(),
+			]);
+		}
+
+		if ((new IntegerType())->isSuperTypeOf($thirdArgType)->yes()) {
+			return new GenericObjectType(DatePeriod::class, [
+				new NullType(),
+				new IntegerType(),
+			]);
+		}
+
+		return new ObjectType(DatePeriod::class);
+	}
+
+}

stubs/date.stub

@@ -9,3 +9,27 @@ class DateInterval
 	public $days;
 
 }
+
+/**
+ * @template TEnd of ?DateTimeInterface
+ * @template TRecurrences of ?int
+ */
+class DatePeriod
+{
+
+	/**
+	 * @return TEnd
+	 */
+	public function getEndDate()
+	{
+
+	}
+
+	/**
+	 * @return TRecurrences
+	 */
+	public function getRecurrences()
+	{
+
+	}
+}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -641,11 +641,14 @@ public function dataFileAsserts(): iterable
 			yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5698-php7.php');
 		}
 
+		if (PHP_VERSION_ID >= 70304) {
+			yield from $this->gatherAssertTypes(__DIR__ . '/data/date-period-return-types.php');
+		}
+
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6404.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6399.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-4357.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5817.php');
-
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/array-column.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/template-null-bound.php');
 	}

tests/PHPStan/Analyser/data/date-period-return-types.php

@@ -0,0 +1,35 @@
+<?php declare(strict_types=1);
+
+use function PHPStan\Testing\assertType;
+
+$start = new DateTime('2012-07-01');
+$interval = new DateInterval('P7D');
+$end = new DateTime('2012-07-31');
+$recurrences = 4;
+$iso = 'R4/2012-07-01T00:00:00Z/P7D';
+
+$datePeriodList = [];
+
+$datePeriod = new DatePeriod($start, $interval, $end);
+assertType(\DatePeriod::class . '<DateTimeInterface, null>', $datePeriod);
+assertType(\DateTimeInterface::class, $datePeriod->getEndDate());
+assertType('null', $datePeriod->getRecurrences());
+$datePeriodList[] = $datePeriod;
+
+$datePeriod = new DatePeriod($start, $interval, $recurrences);
+assertType(\DatePeriod::class . '<null, int>', $datePeriod);
+assertType('null', $datePeriod->getEndDate());
+assertType('int', $datePeriod->getRecurrences());
+$datePeriodList[] = $datePeriod;
+
+$datePeriod = new DatePeriod($iso);
+assertType(\DatePeriod::class . '<null, int>', $datePeriod);
+assertType('null', $datePeriod->getEndDate());
+assertType('int', $datePeriod->getRecurrences());
+$datePeriodList[] = $datePeriod;
+
+/** @var DatePeriod $datePeriod */
+$datePeriod = $datePeriodList[random_int(0, 2)];
+assertType(\DatePeriod::class, $datePeriod);
+assertType(\DateTimeInterface::class . '|null', $datePeriod->getEndDate());
+assertType('int|null', $datePeriod->getRecurrences());