From 8c13aea4e5054f7958febff5913f3b8599db27d8 Mon Sep 17 00:00:00 2001
From: Jean-Luc Herren <jlh@gmx.ch>
Date: Tue, 13 Oct 2020 22:50:47 +0200
Subject: [PATCH] Fix intersection of iterable and array

---
 src/Type/IterableType.php                 |  5 +++
 src/Type/TypeCombinator.php               | 17 +++++++++
 tests/PHPStan/Type/TypeCombinatorTest.php | 44 +++++++++++++++++++++--
 3 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/Type/IterableType.php b/src/Type/IterableType.php
index 3a902ba09e..45cf284c58 100644
--- a/src/Type/IterableType.php
+++ b/src/Type/IterableType.php
@@ -34,6 +34,11 @@ public function __construct(
 		$this->itemType = $itemType;
 	}
 
+	public function getKeyType(): Type
+	{
+		return $this->keyType;
+	}
+
 	public function getItemType(): Type
 	{
 		return $this->itemType;
diff --git a/src/Type/TypeCombinator.php b/src/Type/TypeCombinator.php
index 7c330fee06..9a84fc2978 100644
--- a/src/Type/TypeCombinator.php
+++ b/src/Type/TypeCombinator.php
@@ -738,11 +738,28 @@ public static function intersect(Type ...$types): Type
 					if ($types[$i] instanceof ConstantArrayType && $types[$j] instanceof HasOffsetType) {
 						$types[$i] = $types[$i]->makeOffsetRequired($types[$j]->getOffsetType());
 						array_splice($types, $j--, 1);
+						continue;
 					}
 
 					if ($types[$j] instanceof ConstantArrayType && $types[$i] instanceof HasOffsetType) {
 						$types[$j] = $types[$j]->makeOffsetRequired($types[$i]->getOffsetType());
 						array_splice($types, $i--, 1);
+						continue 2;
+					}
+
+					if (
+						($types[$i] instanceof ArrayType || $types[$i] instanceof IterableType) &&
+						($types[$j] instanceof ArrayType || $types[$j] instanceof IterableType)
+					) {
+						$keyType = self::intersect($types[$i]->getKeyType(), $types[$j]->getKeyType());
+						$itemType = self::intersect($types[$i]->getItemType(), $types[$j]->getItemType());
+						if ($types[$i] instanceof IterableType && $types[$j] instanceof IterableType) {
+							$types[$j] = new IterableType($keyType, $itemType);
+						} else {
+							$types[$j] = new ArrayType($keyType, $itemType);
+						}
+						array_splice($types, $i--, 1);
+						continue 2;
 					}
 
 					continue;
diff --git a/tests/PHPStan/Type/TypeCombinatorTest.php b/tests/PHPStan/Type/TypeCombinatorTest.php
index 90b402791b..35aa806db8 100644
--- a/tests/PHPStan/Type/TypeCombinatorTest.php
+++ b/tests/PHPStan/Type/TypeCombinatorTest.php
@@ -2002,8 +2002,48 @@ public function dataIntersect(): array
 					new ArrayType(new MixedType(), new MixedType()),
 					new IterableType(new MixedType(), new StringType()),
 				],
-				IntersectionType::class,
-				'array&iterable<string>', // this is correct but 'array<string>' would be better
+				ArrayType::class,
+				'array<string>',
+			],
+			[
+				[
+					new ArrayType(new IntegerType(), new MixedType()),
+					new IterableType(new MixedType(), new StringType()),
+				],
+				ArrayType::class,
+				'array<int, string>',
+			],
+			[
+				[
+					new ArrayType(new IntegerType(), new MixedType()),
+					new IterableType(new StringType(), new MixedType()),
+				],
+				NeverType::class,
+				'*NEVER*',
+			],
+			[
+				[
+					new ArrayType(new MixedType(), new IntegerType()),
+					new IterableType(new MixedType(), new StringType()),
+				],
+				NeverType::class,
+				'*NEVER*',
+			],
+			[
+				[
+					new ArrayType(new IntegerType(), new MixedType()),
+					new ArrayType(new MixedType(), new StringType()),
+				],
+				ArrayType::class,
+				'array<int, string>',
+			],
+			[
+				[
+					new IterableType(new IntegerType(), new MixedType()),
+					new IterableType(new MixedType(), new StringType()),
+				],
+				IterableType::class,
+				'iterable<int, string>',
 			],
 			[
 				[