Add regression test for #11100

Closes phpstan/phpstan#11100

Author: phpstan-bot

tests/PHPStan/Rules/Pure/PureMethodRuleTest.php

@@ -279,6 +279,12 @@ public function testAllMethodsArePure(): void
 		]);
 	}
 
+	public function testBug11100(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-11100.php'], []);
+	}
+
 	public function testBug12382(): void
 	{
 		$this->treatPhpDocTypesAsCertain = true;

tests/PHPStan/Rules/Pure/data/bug-11100.php

@@ -0,0 +1,30 @@
+<?php // lint >= 8.0
+
+namespace Bug11100;
+
+final class FooClass
+{
+	/**
+	 * @param array<string, string|int> $getParams
+	 *
+	 * @phpstan-pure
+	 */
+	public function build(array $getParams, string $trailingSlash, bool $useSlashSeparator): string
+	{
+		if ($getParams === []) {
+			return '';
+		}
+
+		if ($useSlashSeparator) {
+			return '/' . implode('/', array_map(
+				static function (string $key, string|int $value): string {
+					return rawurlencode($key) . '/' . rawurlencode((string) $value);
+				},
+				array_keys($getParams),
+				$getParams
+			)) . $trailingSlash;
+		}
+
+		return $trailingSlash . '?' . http_build_query($getParams);
+	}
+}