Added regression test

Author: staabm

Diff for: tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -870,6 +870,13 @@ public function testBug8649(): void
 		$this->analyse([__DIR__ . '/data/bug-8649.php'], []);
 	}
 
+	public function testBug11447(): void
+	{
+		$this->reportPossiblyNonexistentGeneralArrayOffset = true;
+
+		$this->analyse([__DIR__ . '/data/bug-11447.php'], []);
+	}
+
 	public function testNarrowSuperglobals(): void
 	{
 		$this->reportPossiblyNonexistentGeneralArrayOffset = true;

Diff for: tests/PHPStan/Rules/Arrays/data/bug-11447.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Bug11447;
+
+function doFoo() {
+	\assert( \array_key_exists( 'key1', $_GET ) && \is_numeric( $_GET['key1'] ) );
+	\assert( isset( $_GET['key2'] ) && \is_numeric( $_GET['key2'] ) );
+}