Do not report non existent offset for invalid ones

src/Rules/Arrays/NonexistentOffsetInArrayDimFetchCheck.php

@@ -12,7 +12,10 @@
 use PHPStan\Rules\RuleLevelHelper;
 use PHPStan\Type\BenevolentUnionType;
 use PHPStan\Type\ErrorType;
+use PHPStan\Type\MixedType;
+use PHPStan\Type\NeverType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\TypeUtils;
 use PHPStan\Type\VerbosityLevel;
 use function count;
@@ -60,6 +63,14 @@ public function check(
 		}
 
 		if ($type->hasOffsetValueType($dimType)->no()) {
+			if ($type->isArray()->yes()) {
+				$validArrayDimType = TypeCombinator::intersect(AllowedArrayKeysTypes::getType(), $dimType);
+				if ($validArrayDimType instanceof NeverType) {
+					// Already reported by InvalidKeyInArrayDimFetchRule
+					return [];
+				}
+			}
+
 			return [
 				RuleErrorBuilder::message(sprintf('Offset %s does not exist on %s.', $dimType->describe(count($dimType->getConstantStrings()) > 0 ? VerbosityLevel::precise() : VerbosityLevel::value()), $type->describe(VerbosityLevel::value())))
 					->identifier('offsetAccess.notFound')
@@ -76,28 +87,34 @@ public function check(
 				$flattenedTypes = TypeUtils::flattenTypes($type);
 			}
 
+			$validArrayDimType = $dimType instanceof MixedType
+				? $dimType
+				: TypeCombinator::intersect(AllowedArrayKeysTypes::getType(), $dimType);
+
 			foreach ($flattenedTypes as $innerType) {
+				$dimTypeToCheck = $innerType->isArray()->yes() ? $validArrayDimType : $dimType;
+
 				if (
 					$this->reportPossiblyNonexistentGeneralArrayOffset
 					&& $innerType->isArray()->yes()
 					&& !$innerType->isConstantArray()->yes()
-					&& !$innerType->hasOffsetValueType($dimType)->yes()
+					&& !$innerType->hasOffsetValueType($dimTypeToCheck)->yes()
 				) {
 					$report = true;
 					break;
 				}
 				if (
 					$this->reportPossiblyNonexistentConstantArrayOffset
 					&& $innerType->isConstantArray()->yes()
-					&& !$innerType->hasOffsetValueType($dimType)->yes()
+					&& !$innerType->hasOffsetValueType($dimTypeToCheck)->yes()
 				) {
 					$report = true;
 					break;
 				}
-				if ($dimType instanceof BenevolentUnionType) {
-					$flattenedInnerTypes = [$dimType];
+				if ($dimTypeToCheck instanceof BenevolentUnionType) {
+					$flattenedInnerTypes = [$dimTypeToCheck];
 				} else {
-					$flattenedInnerTypes = TypeUtils::flattenTypes($dimType);
+					$flattenedInnerTypes = TypeUtils::flattenTypes($dimTypeToCheck);
 				}
 				foreach ($flattenedInnerTypes as $innerDimType) {
 					if (

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

@@ -3,10 +3,5 @@
         "message": "Invalid array key type DateTimeImmutable.",
         "line": 17,
         "ignorable": true
-    },
-    {
-        "message": "Offset DateTimeImmutable does not exist on array.",
-        "line": 17,
-        "ignorable": true
     }
 ]

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

@@ -1,49 +1,24 @@
 [
-    {
-        "message": "Offset int|object might not exist on array.",
-        "line": 19,
-        "ignorable": true
-    },
     {
         "message": "Possibly invalid array key type int|object.",
         "line": 19,
         "ignorable": true
     },
-    {
-        "message": "Offset object|null might not exist on array.",
-        "line": 20,
-        "ignorable": true
-    },
     {
         "message": "Possibly invalid array key type object|null.",
         "line": 20,
         "ignorable": true
     },
-    {
-        "message": "Offset DateTimeImmutable might not exist on array|ArrayAccess.",
-        "line": 26,
-        "ignorable": true
-    },
     {
         "message": "Possibly invalid array key type DateTimeImmutable.",
         "line": 26,
         "ignorable": true
     },
-    {
-        "message": "Offset int|object might not exist on array|ArrayAccess.",
-        "line": 28,
-        "ignorable": true
-    },
     {
         "message": "Possibly invalid array key type int|object.",
         "line": 28,
         "ignorable": true
     },
-    {
-        "message": "Offset object|null might not exist on array|ArrayAccess.",
-        "line": 29,
-        "ignorable": true
-    },
     {
         "message": "Possibly invalid array key type object|null.",
         "line": 29,

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

@@ -18,10 +18,5 @@
         "message": "Invalid array key type stdClass.",
         "line": 59,
         "ignorable": true
-    },
-    {
-        "message": "Offset stdClass does not exist on array{baz: 21}|array{foo: 17, bar: 19}.",
-        "line": 59,
-        "ignorable": true
     }
 ]

tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -949,10 +949,6 @@ public function testBugObject(): void
 				'Offset int|object does not exist on array{baz: 21}|array{foo: 17, bar: 19}.',
 				12,
 			],
-			[
-				'Offset object does not exist on array<string, int>.',
-				21,
-			],
 		]);
 	}
 
@@ -1049,6 +1045,60 @@ public function testBug13538(): void
 		]);
 	}
 
+	public function testPR4385(): void
+	{
+		$this->reportPossiblyNonexistentGeneralArrayOffset = true;
+		$this->reportPossiblyNonexistentConstantArrayOffset = true;
+
+		$this->analyse([__DIR__ . '/data/pr-4385.php'], [
+			[
+				'Offset int might not exist on array<int>.',
+				24,
+			],
+			[
+				'Offset string might not exist on array<int>.',
+				25,
+			],
+			[
+				'Offset array<int>|int might not exist on array<int>.',
+				28,
+			],
+			[
+				'Offset array<int>|string might not exist on array<int>.',
+				29,
+			],
+			[
+				'Offset 0|array<int> might not exist on array<int>.',
+				30,
+			],
+			[
+				'Offset int might not exist on array{string}.',
+				33,
+			],
+			[
+				'Offset string might not exist on array{string}.',
+				34,
+			],
+			[
+				'Offset array<int>|int might not exist on array{string}.',
+				37,
+			],
+			[
+				'Offset array<int>|string might not exist on array{string}.',
+				38,
+			],
+			[
+				'Offset array<int>|int might not exist on array<int>|string.',
+				41,
+			],
+		]);
+	}
+
+	public function testPR4385Bis(): void
+	{
+		$this->analyse([__DIR__ . '/data/pr-4385-bis.php'], []);
+	}
+
 	public function testBug12805(): void
 	{
 		$this->reportPossiblyNonexistentGeneralArrayOffset = true;

tests/PHPStan/Rules/Arrays/data/pr-4385-bis.php

@@ -0,0 +1,12 @@
+<?php declare(strict_types = 1);
+
+namespace Pr4385Bis;
+
+class HelloWorld
+{
+	/** @param array<string, int> $a */
+	public function sayHello(array $a, mixed $m): void
+	{
+		echo $a[$m];
+	}
+}

tests/PHPStan/Rules/Arrays/data/pr-4385.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace Pr4385;
+
+class Foo
+{
+	/**
+	 * @param array<int> $array
+	 * @param int   $int
+	 * @param string $string
+	 * @param object $object
+	 * @param array{0: string} $constantArray
+	 *
+	 * @return void
+	 */
+	public function test($array, $int, $string, $object, $constantArray)
+	{
+		$arrayOrObject = rand(0, 1) ? $array : $object;
+		$arrayOrInt = rand(0, 1) ? $array : $int;
+		$arrayOrString = rand(0, 1) ? $array : $string;
+		$arrayOrZero = rand(0, 1) ? $array : 0;
+
+		$array[$array];
+		$array[$int];
+		$array[$string];
+		$array[$object]; // Reported by InvalidKeyInArrayDimFetchRule
+		$array[$arrayOrObject]; // Reported by InvalidKeyInArrayDimFetchRule
+		$array[$arrayOrInt];
+		$array[$arrayOrString];
+		$array[$arrayOrZero];
+
+		$constantArray[$array];
+		$constantArray[$int];
+		$constantArray[$string];
+		$constantArray[$object]; // Reported by InvalidKeyInArrayDimFetchRule
+		$constantArray[$arrayOrObject]; // Reported by InvalidKeyInArrayDimFetchRule
+		$constantArray[$arrayOrInt];
+		$constantArray[$arrayOrString];
+		$constantArray[$arrayOrZero]; // Reported by InvalidKeyInArrayDimFetchRule
+
+		$arrayOrString[$arrayOrInt];
+	}
+}