Fix

Author: VincentLanglet

src/Rules/Arrays/NonexistentOffsetInArrayDimFetchCheck.php

@@ -14,7 +14,6 @@
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeUtils;
-use PHPStan\Type\UnionType;
 use PHPStan\Type\VerbosityLevel;
 use function count;
 use function sprintf;
@@ -77,6 +76,7 @@ public function check(
 				$flattenedTypes = TypeUtils::flattenTypes($type);
 			}
 
+			$allowedArrayKeysTypes = AllowedArrayKeysTypes::getType();
 			foreach ($flattenedTypes as $innerType) {
 				if (
 					$this->reportPossiblyNonexistentGeneralArrayOffset
@@ -95,17 +95,16 @@ public function check(
 					$report = true;
 					break;
 				}
-				if ($dimType instanceof UnionType) {
-					foreach ($dimType->getTypes() as $subDimType) {
-						if ($innerType->hasOffsetValueType($subDimType)->no()) {
-							$report = true;
-							break 2;
-						}
-					}
-					continue;
+				if ($dimType instanceof BenevolentUnionType) {
+					$flattenedInnerTypes = [$dimType];
+				} else {
+					$flattenedInnerTypes = TypeUtils::flattenTypes($dimType);
 				}
-				foreach (TypeUtils::flattenTypes($dimType) as $innerDimType) {
-					if ($innerType->hasOffsetValueType($innerDimType)->no()) {
+				foreach ($flattenedInnerTypes as $innerDimType) {
+					if (
+						$allowedArrayKeysTypes->isSuperTypeOf($innerDimType)->yes()
+						&& $innerType->hasOffsetValueType($innerDimType)->no()
+					) {
 						$report = true;
 						break 2;
 					}

tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -132,7 +132,7 @@ public function testRule(): void
 				312,
 			],
 			[
-				' Offset int|null might not exist on array<string, string>.',
+				'Offset int|null might not exist on array<string, string>.',
 				314,
 			],
 			[
@@ -193,10 +193,6 @@ public function testStrings(): void
 				'Offset 12.34 does not exist on \'foo\'.',
 				13,
 			],
-			[
-				"Offset int|object might not exist on 'foo'.",
-				16,
-			],
 			[
 				'Offset \'foo\' might not exist on array|string.',
 				24,
@@ -205,10 +201,6 @@ public function testStrings(): void
 				'Offset 12.34 might not exist on array|string.',
 				28,
 			],
-			[
-				'Offset int|object might not exist on array|string.',
-				32,
-			],
 		]);
 	}