diff --git a/resources/functionMap_php80delta.php b/resources/functionMap_php80delta.php
index f1735f2a4e..a90cd9af3d 100644
--- a/resources/functionMap_php80delta.php
+++ b/resources/functionMap_php80delta.php
@@ -22,6 +22,7 @@
 return [
 	'new' => [
 		'array_combine' => ['associative-array', 'keys'=>'string[]|int[]', 'values'=>'array'],
+		'array_fill' => ['array', 'start_key'=>'int', 'num'=>'0|positive-int', 'val'=>'mixed'],
 		'bcdiv' => ['string', 'dividend'=>'string', 'divisor'=>'string', 'scale='=>'int'],
 		'bcmod' => ['string', 'dividend'=>'string', 'divisor'=>'string', 'scale='=>'int'],
 		'bcpowmod' => ['string', 'base'=>'string', 'exponent'=>'string', 'modulus'=>'string', 'scale='=>'int'],
@@ -146,6 +147,7 @@
 	'old' => [
 
 		'array_combine' => ['associative-array|false', 'keys'=>'string[]|int[]', 'values'=>'array'],
+		'array_fill' => ['array', 'start_key'=>'int', 'num'=>'int', 'val'=>'mixed'],
 		'bcdiv' => ['?string', 'dividend'=>'string', 'divisor'=>'string', 'scale='=>'int'],
 		'bcmod' => ['?string', 'dividend'=>'string', 'divisor'=>'string', 'scale='=>'int'],
 		'bcpowmod' => ['?string', 'base'=>'string', 'exponent'=>'string', 'modulus'=>'string', 'scale='=>'int'],
diff --git a/src/File/ParentDirectoryRelativePathHelper.php b/src/File/ParentDirectoryRelativePathHelper.php
index 306f8f0dbf..b88c930758 100644
--- a/src/File/ParentDirectoryRelativePathHelper.php
+++ b/src/File/ParentDirectoryRelativePathHelper.php
@@ -54,6 +54,9 @@ public function getFilenameParts(string $filename): array
 		}
 
 		$dotsCount = $parentPartsCount - $i;
+		if ($dotsCount < 0) {
+			throw new \PHPStan\ShouldNotHappenException();
+		}
 
 		return array_merge(array_fill(0, $dotsCount, '..'), array_slice($filenameParts, $i));
 	}
diff --git a/src/Type/Php/ArrayFillFunctionReturnTypeExtension.php b/src/Type/Php/ArrayFillFunctionReturnTypeExtension.php
index c1a8c168dd..ab42e9a5d9 100644
--- a/src/Type/Php/ArrayFillFunctionReturnTypeExtension.php
+++ b/src/Type/Php/ArrayFillFunctionReturnTypeExtension.php
@@ -4,21 +4,33 @@
 
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
+use PHPStan\Php\PhpVersion;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
 use PHPStan\Type\ArrayType;
 use PHPStan\Type\Constant\ConstantArrayTypeBuilder;
+use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\Constant\ConstantIntegerType;
+use PHPStan\Type\IntegerRangeType;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\IntersectionType;
+use PHPStan\Type\NeverType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 
 class ArrayFillFunctionReturnTypeExtension implements \PHPStan\Type\DynamicFunctionReturnTypeExtension
 {
 
 	private const MAX_SIZE_USE_CONSTANT_ARRAY = 100;
 
+	private PhpVersion $phpVersion;
+
+	public function __construct(PhpVersion $phpVersion)
+	{
+		$this->phpVersion = $phpVersion;
+	}
+
 	public function isFunctionSupported(FunctionReflection $functionReflection): bool
 	{
 		return $functionReflection->getName() === 'array_fill';
@@ -34,6 +46,23 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 		$numberType = $scope->getType($functionCall->args[1]->value);
 		$valueType = $scope->getType($functionCall->args[2]->value);
 
+		if ($numberType instanceof IntegerRangeType) {
+			if ($numberType->getMin() < 0) {
+				return TypeCombinator::union(
+					new ArrayType(new IntegerType(), $valueType),
+					new ConstantBooleanType(false)
+				);
+			}
+		}
+
+		// check against negative-int, which is not allowed
+		if (IntegerRangeType::fromInterval(null, -1)->isSuperTypeOf($numberType)->yes()) {
+			if ($this->phpVersion->throwsValueErrorForInternalFunctions()) {
+				return new NeverType();
+			}
+			return new ConstantBooleanType(false);
+		}
+
 		if (
 			$startIndexType instanceof ConstantIntegerType
 			&& $numberType instanceof ConstantIntegerType
@@ -56,10 +85,7 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 			return $arrayBuilder->getArray();
 		}
 
-		if (
-			$numberType instanceof ConstantIntegerType
-			&& $numberType->getValue() > 0
-		) {
+		if (IntegerRangeType::fromInterval(1, null)->isSuperTypeOf($numberType)->yes()) {
 			return new IntersectionType([
 				new ArrayType(new IntegerType(), $valueType),
 				new NonEmptyArrayType(),
diff --git a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
index 27983a2c6a..6971ea40f0 100644
--- a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
@@ -5100,10 +5100,34 @@ public function dataArrayFunctions(): array
 				'array(1, 1, 1, 1, 1)',
 				'$filledIntegers',
 			],
+			[
+				'array()',
+				'$emptyFilled',
+			],
 			[
 				'array(1)',
 				'$filledIntegersWithKeys',
 			],
+			[
+				'array<int, \'foo\'>&nonEmpty',
+				'$filledNonEmptyArray',
+			],
+			[
+				PHP_VERSION_ID < 80000 ? 'false' : '*NEVER*',
+				'$filledAlwaysFalse',
+			],
+			[
+				PHP_VERSION_ID < 80000 ? 'false' : '*NEVER*',
+				'$filledNegativeConstAlwaysFalse',
+			],
+			[
+				'array<int, 1>|false',
+				'$filledByMaybeNegativeRange',
+			],
+			[
+				'array<int, 1>&nonEmpty',
+				'$filledByPositiveRange',
+			],
 			[
 				'array(1, 2)',
 				'array_keys($integerKeys)',
diff --git a/tests/PHPStan/Analyser/data/array-functions.php b/tests/PHPStan/Analyser/data/array-functions.php
index 752fe4fd07..15d7252487 100644
--- a/tests/PHPStan/Analyser/data/array-functions.php
+++ b/tests/PHPStan/Analyser/data/array-functions.php
@@ -37,7 +37,16 @@
 }, 1);
 
 $filledIntegers = array_fill(0, 5, 1);
+$emptyFilled = array_fill(3, 0, 'banana');
 $filledIntegersWithKeys = array_fill_keys([0], 1);
+/** @var negative-int $negInt */
+$filledAlwaysFalse = array_fill(0, $negInt, 1);
+/** @var positive-int $posInt */
+$filledNonEmptyArray = array_fill(0, $posInt, 'foo');
+$filledNegativeConstAlwaysFalse = array_fill(0, -5, 1);
+/** @var int<-3, 5> $maybeNegRange */
+$filledByMaybeNegativeRange = array_fill(0, $maybeNegRange, 1);
+$filledByPositiveRange = array_fill(0, rand(3, 5), 1);
 
 $integerKeys = [
 	1 => 'foo',
diff --git a/tests/PHPStan/Parallel/SchedulerTest.php b/tests/PHPStan/Parallel/SchedulerTest.php
index e029e06d9b..538dd69016 100644
--- a/tests/PHPStan/Parallel/SchedulerTest.php
+++ b/tests/PHPStan/Parallel/SchedulerTest.php
@@ -73,7 +73,7 @@ public function dataSchedule(): array
 	 * @param int $maximumNumberOfProcesses
 	 * @param int $minimumNumberOfJobsPerProcess
 	 * @param int $jobSize
-	 * @param int $numberOfFiles
+	 * @param 0|positive-int $numberOfFiles
 	 * @param int $expectedNumberOfProcesses
 	 * @param array<int> $expectedJobSizes
 	 */