From 457b1958e89bae5c7f4cebea26ee7a47ab77e627 Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sat, 27 Sep 2025 13:49:25 +0200
Subject: [PATCH 1/2] Improve ConstantArrayType inference

---
 src/Type/ArrayType.php                    | 17 +++++++++++++++++
 tests/PHPStan/Analyser/nsrt/bug-11846.php |  6 +++---
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/src/Type/ArrayType.php b/src/Type/ArrayType.php
index 88a7617901..35362de99f 100644
--- a/src/Type/ArrayType.php
+++ b/src/Type/ArrayType.php
@@ -371,6 +371,23 @@ public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $uni
 
 	public function setExistingOffsetValueType(Type $offsetType, Type $valueType): Type
 	{
+		if ($this->itemType->isConstantArray()->yes() && $valueType->isConstantArray()->yes()) {
+			$constArrays = $valueType->getConstantArrays();
+			$newItemType = $this->itemType;
+			foreach ($constArrays as $constArray) {
+				foreach ($constArray->getKeyTypes() as $keyType) {
+					$newItemType = $newItemType->setExistingOffsetValueType($keyType, $constArray->getOffsetValueType($keyType));
+				}
+			}
+
+			if ($newItemType !== $this->itemType) {
+				return new self(
+					$this->keyType,
+					$newItemType,
+				);
+			}
+		}
+
 		return new self(
 			$this->keyType,
 			TypeCombinator::union($this->itemType, $valueType),
diff --git a/tests/PHPStan/Analyser/nsrt/bug-11846.php b/tests/PHPStan/Analyser/nsrt/bug-11846.php
index 06fbcd8313..02ace75d07 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-11846.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-11846.php
@@ -13,16 +13,16 @@ function demo(): void
 		$outerList[$id] = [];
 		array_push($outerList[$id], []);
 	}
-	assertType('non-empty-array<1|2, array{}|array{array{}}>', $outerList);
+	assertType('non-empty-array<1|2, array{array{}}>', $outerList);
 
 	foreach ($outerList as $key => $outerElement) {
 		$result = false;
 
-		assertType('array{}|array{array{}}', $outerElement);
+		assertType('array{array{}}', $outerElement);
 		foreach ($outerElement as $innerElement) {
 			$result = true;
 		}
-		assertType('bool', $result); // could be 'true'
+		assertType('true', $result);
 
 	}
 }

From 724286f27f7af263355c36690ed0e679c6185fdd Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sat, 27 Sep 2025 13:51:27 +0200
Subject: [PATCH 2/2] Update ArrayType.php

---
 src/Type/ArrayType.php | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/Type/ArrayType.php b/src/Type/ArrayType.php
index 35362de99f..9f87759790 100644
--- a/src/Type/ArrayType.php
+++ b/src/Type/ArrayType.php
@@ -372,9 +372,8 @@ public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $uni
 	public function setExistingOffsetValueType(Type $offsetType, Type $valueType): Type
 	{
 		if ($this->itemType->isConstantArray()->yes() && $valueType->isConstantArray()->yes()) {
-			$constArrays = $valueType->getConstantArrays();
 			$newItemType = $this->itemType;
-			foreach ($constArrays as $constArray) {
+			foreach ($valueType->getConstantArrays() as $constArray) {
 				foreach ($constArray->getKeyTypes() as $keyType) {
 					$newItemType = $newItemType->setExistingOffsetValueType($keyType, $constArray->getOffsetValueType($keyType));
 				}