Respect phpstan level in InvalidKeyInArrayDimFetchRule

src/Rules/Arrays/InvalidKeyInArrayDimFetchRule.php

@@ -10,7 +10,6 @@
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Rules\RuleLevelHelper;
 use PHPStan\Type\ErrorType;
-use PHPStan\Type\MixedType;
 use PHPStan\Type\Type;
 use PHPStan\Type\VerbosityLevel;
 use function sprintf;
@@ -41,22 +40,27 @@ public function processNode(Node $node, Scope $scope): array
 			return [];
 		}
 
-		$dimensionType = $scope->getType($node->dim);
-		if ($dimensionType instanceof MixedType) {
-			return [];
-		}
-
 		$varType = $this->ruleLevelHelper->findTypeToCheck(
 			$scope,
 			$node->var,
 			'',
-			static fn (Type $varType): bool => $varType->isArray()->no() || AllowedArrayKeysTypes::getType()->isSuperTypeOf($dimensionType)->yes(),
+			static fn (Type $varType): bool => $varType->isArray()->no(),
 		)->getType();
 
 		if ($varType instanceof ErrorType || $varType->isArray()->no()) {
 			return [];
 		}
 
+		$dimensionType = $this->ruleLevelHelper->findTypeToCheck(
+			$scope,
+			$node->dim,
+			'',
+			static fn (Type $dimType): bool => AllowedArrayKeysTypes::getType()->isSuperTypeOf($dimType)->yes(),
+		)->getType();
+		if ($dimensionType instanceof ErrorType) {
+			return [];
+		}
+
 		$isSuperType = AllowedArrayKeysTypes::getType()->isSuperTypeOf($dimensionType);
 		if ($isSuperType->yes() || ($isSuperType->maybe() && !$this->reportMaybes)) {
 			return [];

src/Rules/RuleLevelHelper.php

@@ -190,7 +190,11 @@ private function findTypeToCheckImplementation(
 		bool $isTopLevel = false,
 	): FoundTypeResult
 	{
-		if (!$this->checkNullables && !$type->isNull()->yes()) {
+		if (
+			!$this->checkNullables
+			&& !$type->isNull()->yes()
+			&& !$unionTypeCriteriaCallback(new NullType())
+		) {
 			$type = TypeCombinator::removeNull($type);
 		}
 

tests/PHPStan/Levels/LevelsIntegrationTest.php

@@ -41,6 +41,7 @@ public static function dataTopics(): array
 			['arrayDestructuring'],
 			['listType'],
 			['missingTypes'],
+			['arrayOffsetAccess'],
 		];
 		if (PHP_VERSION_ID >= 80300) {
 			$topics[] = ['constantAccesses83'];

tests/PHPStan/Levels/data/arrayOffsetAccess-10.json

@@ -0,0 +1,7 @@
+[
+    {
+        "message": "Possibly invalid array key type mixed.",
+        "line": 22,
+        "ignorable": true
+    }
+]

tests/PHPStan/Levels/data/arrayOffsetAccess-3.json

@@ -0,0 +1,7 @@
+[
+    {
+        "message": "Invalid array key type DateTimeImmutable.",
+        "line": 17,
+        "ignorable": true
+    }
+]

tests/PHPStan/Levels/data/arrayOffsetAccess-4.json

@@ -0,0 +1,37 @@
+[
+    {
+        "message": "Expression \"$a[42]\" on a separate line does not do anything.",
+        "line": 15,
+        "ignorable": true
+    },
+    {
+        "message": "Expression \"$a[null]\" on a separate line does not do anything.",
+        "line": 16,
+        "ignorable": true
+    },
+    {
+        "message": "Expression \"$a[$intOrNull]\" on a separate line does not do anything.",
+        "line": 18,
+        "ignorable": true
+    },
+    {
+        "message": "Expression \"$a[$objectOrInt]\" on a separate line does not do anything.",
+        "line": 19,
+        "ignorable": true
+    },
+    {
+        "message": "Expression \"$a[$objectOrNull]\" on a separate line does not do anything.",
+        "line": 20,
+        "ignorable": true
+    },
+    {
+        "message": "Expression \"$a[$explicitlyMixed]\" on a separate line does not do anything.",
+        "line": 21,
+        "ignorable": true
+    },
+    {
+        "message": "Expression \"$a[$implicitlyMixed]\" on a separate line does not do anything.",
+        "line": 22,
+        "ignorable": true
+    }
+]

tests/PHPStan/Levels/data/arrayOffsetAccess-6.json

@@ -0,0 +1,12 @@
+[
+    {
+        "message": "Method Levels\\ArrayOffsetAccess\\Foo::test() has parameter $a with no value type specified in iterable type array.",
+        "line": 13,
+        "ignorable": true
+    },
+    {
+        "message": "Method Levels\\ArrayOffsetAccess\\Foo::test() has parameter $implicitlyMixed with no type specified.",
+        "line": 13,
+        "ignorable": true
+    }
+]

tests/PHPStan/Levels/data/arrayOffsetAccess-7.json

@@ -0,0 +1,12 @@
+[
+    {
+        "message": "Possibly invalid array key type int|object.",
+        "line": 19,
+        "ignorable": true
+    },
+    {
+        "message": "Possibly invalid array key type object|null.",
+        "line": 20,
+        "ignorable": true
+    }
+]

tests/PHPStan/Levels/data/arrayOffsetAccess-9.json

@@ -0,0 +1,7 @@
+[
+    {
+        "message": "Possibly invalid array key type mixed.",
+        "line": 21,
+        "ignorable": true
+    }
+]

tests/PHPStan/Levels/data/arrayOffsetAccess.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Levels\ArrayOffsetAccess;
+
+class Foo {
+	/**
+	 * @param int|null $intOrNull
+	 * @param object|int $objectOrInt
+	 * @param object|null $objectOrNull
+	 * @param mixed $explicitlyMixed
+	 * @return void
+	 */
+	public function test(array $a, $intOrNull, $objectOrInt, $objectOrNull, $explicitlyMixed, $implicitlyMixed)
+	{
+		$a[42];
+		$a[null];
+		$a[new \DateTimeImmutable()];
+		$a[$intOrNull];
+		$a[$objectOrInt];
+		$a[$objectOrNull];
+		$a[$explicitlyMixed];
+		$a[$implicitlyMixed];
+	}
+}