From 64fdac33e86ac7f9d6f10c0a9d5310af843cd854 Mon Sep 17 00:00:00 2001
From: Matt Brown <github@muglug.com>
Date: Sun, 25 Apr 2021 10:45:43 -0400
Subject: [PATCH] Fix #5641 - types should always be comparable to themselves

---
 .../Type/Comparator/ScalarTypeComparator.php  |  6 ++
 tests/TypeComparatorTest.php                  | 81 +++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 tests/TypeComparatorTest.php

diff --git a/src/Psalm/Internal/Type/Comparator/ScalarTypeComparator.php b/src/Psalm/Internal/Type/Comparator/ScalarTypeComparator.php
index a00da2ccf..c6ec7fe3f 100644
--- a/src/Psalm/Internal/Type/Comparator/ScalarTypeComparator.php
+++ b/src/Psalm/Internal/Type/Comparator/ScalarTypeComparator.php
@@ -265,6 +265,12 @@ class ScalarTypeComparator
             return true;
         }
 
+        if ($container_type_part instanceof TNonFalsyString
+            && $input_type_part instanceof TNonFalsyString
+        ) {
+            return true;
+        }
+
         if ($container_type_part instanceof TNonFalsyString
             && $input_type_part instanceof TNonEmptyString
         ) {
diff --git a/tests/TypeComparatorTest.php b/tests/TypeComparatorTest.php
new file mode 100644
index 000000000..98da10b6b
--- /dev/null
+++ b/tests/TypeComparatorTest.php
@@ -0,0 +1,81 @@
+<?php
+namespace Psalm\Tests;
+
+use function function_exists;
+use function print_r;
+use function mb_substr;
+use function stripos;
+
+use Psalm\Internal\RuntimeCaches;
+use Psalm\Type;
+
+class TypeComparatorTest extends TestCase
+{
+    public function setUp() : void
+    {
+        RuntimeCaches::clearAll();
+        $this->file_provider = new \Psalm\Tests\Internal\Provider\FakeFileProvider();
+
+        $config = new TestConfig();
+
+        $providers = new \Psalm\Internal\Provider\Providers(
+            $this->file_provider,
+            new \Psalm\Tests\Internal\Provider\FakeParserCacheProvider()
+        );
+
+        $this->project_analyzer = new \Psalm\Internal\Analyzer\ProjectAnalyzer(
+            $config,
+            $providers
+        );
+    }
+
+    /**
+     * @dataProvider getAllBasicTypes
+     */
+    public function testTypeAcceptsItself(string $type_string): void
+    {
+        $type_1 = \Psalm\Type::parseString($type_string);
+        $type_2 = \Psalm\Type::parseString($type_string);
+
+        $this->assertTrue(
+            \Psalm\Internal\Type\Comparator\UnionTypeComparator::isContainedBy(
+                $this->project_analyzer->getCodebase(),
+                $type_1,
+                $type_2
+            )
+        );
+    }
+
+    /**
+     * @return array<array{string}>
+     */
+    public function getAllBasicTypes(): array
+    {
+        // these types are not valid without generics attached
+        $basic_generic_types = [
+            'key-of' => true,
+            'arraylike-object' => true,
+            'value-of' => true,
+            'class-string-map' => true,
+            'int-mask-of' => true,
+            'int-mask' => true,
+            'pure-Closure' => true,
+        ];
+
+        $basic_types = array_diff_key(
+            \Psalm\Internal\Type\TypeTokenizer::PSALM_RESERVED_WORDS,
+            $basic_generic_types,
+            [
+                'open-resource' => true, // unverifiable
+                'mysql-escaped-string' => true, // deprecated
+                'non-empty-countable' => true, // bit weird, maybe a bug?
+            ]
+        );
+        return array_map(
+            function ($type) {
+                return [$type];
+            },
+            array_keys($basic_types)
+        );
+    }
+}