Add non-regression tests for phpstan/phpstan#13421 and phpstan/phpstan#8864

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/bug-13421.php

@@ -0,0 +1,26 @@
+<?php // lint >= 8.1
+
+declare(strict_types = 1);
+
+namespace Bug13421;
+
+use function PHPStan\Testing\assertType;
+
+enum Bar
+{
+	case Bar1;
+	case Bar2;
+	case Bar3;
+}
+
+/**
+ * @param non-empty-array<Bar> $nonEmptyFilterArray
+ */
+function test(array $nonEmptyFilterArray): void
+{
+	$bars = [Bar::Bar1, Bar::Bar2, Bar::Bar3];
+
+	$filteredBars = array_filter($bars, fn (Bar $bar) => in_array($bar, $nonEmptyFilterArray));
+
+	assertType("array{0?: Bug13421\Bar::Bar1, 1?: Bug13421\Bar::Bar2, 2?: Bug13421\Bar::Bar3}", $filteredBars);
+}

tests/PHPStan/Analyser/nsrt/bug-8864.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Bug8864;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param array{0: 1, 1?: 2} $a
+ */
+function test(array $a): void
+{
+	if (in_array(2, $a, true)) {
+		assertType('array{0: 1, 1?: 2}', $a);
+	}
+
+	// TODO: value type of optional key should not be narrowed to *NEVER*
+	if (!in_array(2, $a, true)) {
+		assertType('array{0: 1, 1?: *NEVER*}', $a);
+	}
+}
+
+/**
+ * @param 1|2 $x
+ * @param array{0: 1, 1?: 2} $a
+ */
+function testNeedle($x, array $a): void
+{
+	if (in_array($x, $a, true)) {
+		assertType('1|2', $x);
+	}
+
+	if (!in_array($x, $a, true)) {
+		// 1 is guaranteed in the array, so if not in_array, x must be 2
+		assertType('2', $x);
+	}
+}