From 5e53a266bab8c93d7cc784a871275d47811679af Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sun, 3 May 2026 09:57:49 +0200
Subject: [PATCH] Added regression test

---
 tests/PHPStan/Analyser/nsrt/bug-9004.php       | 18 ++++++++++++++++++
 .../Arrays/OffsetAccessAssignmentRuleTest.php  | 11 +++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 tests/PHPStan/Analyser/nsrt/bug-9004.php

diff --git a/tests/PHPStan/Analyser/nsrt/bug-9004.php b/tests/PHPStan/Analyser/nsrt/bug-9004.php
new file mode 100644
index 0000000000..2bb2f70163
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-9004.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Bug9004;
+
+use function PHPStan\Testing\assertType;
+
+$test = [];
+foreach (['a', 'b', 'c'] as $letter) {
+	if (rand(0, 1) == 0) {
+		assertType("array{}|array{hi: 'hello'}|array{hi: array{0: 42, 1?: 42}}", $test);
+		if (isset($test['hi']) && is_string($test['hi'])) {
+			continue;
+		}
+		$test['hi'][] = 42;
+	} else {
+		$test['hi'] = 'hello';
+	}
+}
diff --git a/tests/PHPStan/Rules/Arrays/OffsetAccessAssignmentRuleTest.php b/tests/PHPStan/Rules/Arrays/OffsetAccessAssignmentRuleTest.php
index 4ee0a096b6..6bddc862c8 100644
--- a/tests/PHPStan/Rules/Arrays/OffsetAccessAssignmentRuleTest.php
+++ b/tests/PHPStan/Rules/Arrays/OffsetAccessAssignmentRuleTest.php
@@ -222,4 +222,15 @@ public function testAppendToArrayWithPhpIntMaxKey(): void
 		]);
 	}
 
+	public function testBug9004(): void
+	{
+		$this->checkUnionTypes = true;
+		$this->analyse([__DIR__ . '/../../Analyser/nsrt/bug-9004.php'], [
+			[
+				'Cannot assign new offset to list<int>|string.',
+				14,
+			],
+		]);
+	}
+
 }