Report non existent offset on non empty array

Author: VincentLanglet

src/Type/TypeUtils.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Type;
 
+use PHPStan\Internal\CombinationsHelper;
 use PHPStan\Type\Accessory\AccessoryType;
 use PHPStan\Type\Accessory\HasPropertyType;
 use PHPStan\Type\Constant\ConstantArrayType;
@@ -133,17 +134,28 @@ public static function flattenTypes(Type $type): array
 			return $type->getAllArrays();
 		}
 
+		if ($type instanceof IntersectionType && $type->isConstantArray()->yes()) {
+			$newTypes = [];
+			foreach ($type->getTypes() as $innerType) {
+				$newTypes[] = self::flattenTypes($innerType);
+			}
+
+			return array_filter(
+				array_map(
+					static fn (array $types): Type => TypeCombinator::intersect(...$types),
+					iterator_to_array(CombinationsHelper::combinations($newTypes)),
+				),
+				static fn (Type $type): bool => !$type instanceof NeverType,
+			);
+		}
+
 		if ($type instanceof UnionType) {
 			$types = [];
 			foreach ($type->getTypes() as $innerType) {
-				if ($innerType instanceof ConstantArrayType) {
-					foreach ($innerType->getAllArrays() as $array) {
-						$types[] = $array;
-					}
-					continue;
+				$flattenTypes = self::flattenTypes($innerType);
+				foreach ($flattenTypes as $flattenType) {
+					$types[] = $flattenType;
 				}
-
-				$types[] = $innerType;
 			}
 
 			return $types;

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -983,7 +983,7 @@ public function testBug7581(): void
 	public function testBug7903(): void
 	{
 		$errors = $this->runAnalyse(__DIR__ . '/data/bug-7903.php');
-		$this->assertCount(23, $errors);
+		$this->assertCount(28, $errors);
 	}
 
 	public function testBug7901(): void

tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -1049,6 +1049,20 @@ public function testBug13538(): void
 		]);
 	}
 
+	public function testBug7143(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-7143.php'], [
+			[
+				"Offset 'foo' might not exist on non-empty-array{foo?: string, bar?: string}.",
+				12,
+			],
+			[
+				"Offset 'bar' might not exist on non-empty-array{foo?: string, bar?: string}.",
+				13,
+			],
+		]);
+	}
+
 	public function testBug12805(): void
 	{
 		$this->reportPossiblyNonexistentGeneralArrayOffset = true;

tests/PHPStan/Rules/Arrays/data/bug-7143.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Bug7143;
+
+class Foo
+{
+	/**
+	 * @param array{foo?: string, bar?: string}&non-empty-array $arr
+	 */
+	public function test(array $arr): void
+	{
+		echo $arr['foo'];
+		echo $arr['bar'];
+	}
+}