From 428baf5f91fa623a51c236a899f308408b3d85fd Mon Sep 17 00:00:00 2001
From: Ondrej Mirtes <ondrej@mirtes.cz>
Date: Fri, 14 May 2021 13:47:07 +0200
Subject: [PATCH] String starting with \ is valid class name

---
 src/Reflection/ClassNameHelper.php             |  2 +-
 .../Rules/Classes/InstantiationRuleTest.php    |  5 +++++
 tests/PHPStan/Rules/Classes/data/bug-5002.php  | 18 ++++++++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 tests/PHPStan/Rules/Classes/data/bug-5002.php

diff --git a/src/Reflection/ClassNameHelper.php b/src/Reflection/ClassNameHelper.php
index d18c1a6357..803129f14a 100644
--- a/src/Reflection/ClassNameHelper.php
+++ b/src/Reflection/ClassNameHelper.php
@@ -10,7 +10,7 @@ class ClassNameHelper
 	public static function isValidClassName(string $name): bool
 	{
 		// from https://stackoverflow.com/questions/3195614/validate-class-method-names-with-regex#comment104531582_12011255
-		return Strings::match($name, '/^[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*(\\\\[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*)*$/') !== null;
+		return Strings::match(ltrim($name, '\\'), '/^[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*(\\\\[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*)*$/') !== null;
 	}
 
 }
diff --git a/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php b/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
index 47e51ea7ed..7faa259d64 100644
--- a/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
+++ b/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
@@ -342,4 +342,9 @@ public function testBug3425(): void
 		]);
 	}
 
+	public function testBug5002(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-5002.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Classes/data/bug-5002.php b/tests/PHPStan/Rules/Classes/data/bug-5002.php
new file mode 100644
index 0000000000..729720272c
--- /dev/null
+++ b/tests/PHPStan/Rules/Classes/data/bug-5002.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Test;
+
+class Foo
+{
+
+}
+
+function (): void {
+	$name = '\Test\Foo';
+	new $name();
+};
+
+function (): void {
+	$name = '\\Test\Foo';
+	new $name();
+};