Regression test for #3782

Author: ondrejmirtes

tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -235,4 +235,14 @@ public function testIntersection(): void
 		$this->analyse([__DIR__ . '/data/nonexistent-offset-intersection.php'], []);
 	}
 
+	public function testBug3782(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-3782.php'], [
+			[
+				'Cannot access offset (int|string) on Bug3782\HelloWorld.',
+				11,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Arrays/data/bug-3782.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Bug3782;
+
+class HelloWorld
+{
+	/** @param mixed[] $data */
+	public function sayHello(array $data): void
+	{
+		foreach($data as $key => $value){
+			$this[$key] = $value;
+		}
+	}
+}