From e830b23d7745c051caca91008b0091cf8a1661ae Mon Sep 17 00:00:00 2001
From: Marco Pivetta <ocramius@gmail.com>
Date: Thu, 19 Mar 2020 15:11:47 +0100
Subject: [PATCH] Marking `Uuid::uuid5()` as pure: same input leads to same
 output, and no I/O under normal operational constraints

---
 src/Uuid.php                              | 3 +++
 tests/static-analysis/UuidIsImmutable.php | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/src/Uuid.php b/src/Uuid.php
index 4f4045b..3f7e394 100644
--- a/src/Uuid.php
+++ b/src/Uuid.php
@@ -538,6 +538,9 @@ class Uuid implements UuidInterface
      *
      * @return UuidInterface A UuidInterface instance that represents a
      *     version 5 UUID
+     *
+     * @psalm-pure note: changing the internal factory is an edge case not covered by purity invariants,
+     *             but under constant factory setups, this method operates in functionally pure manners
      */
     public static function uuid5($ns, string $name): UuidInterface
     {
diff --git a/tests/static-analysis/UuidIsImmutable.php b/tests/static-analysis/UuidIsImmutable.php
index 6b5a246..4c827fd 100644
--- a/tests/static-analysis/UuidIsImmutable.php
+++ b/tests/static-analysis/UuidIsImmutable.php
@@ -89,4 +89,13 @@ final class UuidIsImmutable
             Uuid::isValid('ff6f8cb0-c57d-11e1-9b21-0800200c9a66'),
         ];
     }
+
+    /** @psalm-pure */
+    public static function uuid5IsPure(): UuidInterface
+    {
+        return Uuid::uuid5(
+            Uuid::fromString('ff6f8cb0-c57d-11e1-9b21-0800200c9a66'),
+            'Look ma! I am a pure function!'
+        );
+    }
 }