From caf9602cb8f3380d9f552951294c14ee9eff3c65 Mon Sep 17 00:00:00 2001
From: orklah <ronan_morin@hotmail.com>
Date: Mon, 25 Oct 2021 18:51:50 +0200
Subject: [PATCH 1/2] don't emit redundant error when checking a named type
 against itself

---
 src/Psalm/Internal/Type/AssertionReconciler.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Psalm/Internal/Type/AssertionReconciler.php b/src/Psalm/Internal/Type/AssertionReconciler.php
index 2adf16565..a4e05184b 100644
--- a/src/Psalm/Internal/Type/AssertionReconciler.php
+++ b/src/Psalm/Internal/Type/AssertionReconciler.php
@@ -457,6 +457,9 @@ class AssertionReconciler extends \Psalm\Type\Reconciler
             if ($key
                 && $code_location
                 && $new_type->getId() === $existing_var_type->getId()
+                //even if two objects are the same, equality is not guaranteed
+                // example: (ErrorException and TypeError are both Throwable but not equal)
+                && !$new_type->hasNamedObjectType()
                 && !$is_equality
                 && !($original_assertion === 'loaded-class-string' && $old_var_type_string === 'class-string')
                 && (!($statements_analyzer->getSource()->getSource() instanceof TraitAnalyzer)

From 8e0cf0e74bee1af22db5da514472f0333170834c Mon Sep 17 00:00:00 2001
From: orklah <ronan_morin@hotmail.com>
Date: Mon, 25 Oct 2021 20:16:58 +0200
Subject: [PATCH 2/2] add test

---
 tests/TypeReconciliation/TypeAlgebraTest.php | 36 ++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/tests/TypeReconciliation/TypeAlgebraTest.php b/tests/TypeReconciliation/TypeAlgebraTest.php
index d5f774e86..3b9167583 100644
--- a/tests/TypeReconciliation/TypeAlgebraTest.php
+++ b/tests/TypeReconciliation/TypeAlgebraTest.php
@@ -1102,6 +1102,42 @@ class TypeAlgebraTest extends \Psalm\Tests\TestCase
                         }
                     }'
             ],
+            'ThrowableInstanceOfThrowableMayBeFalse' => [
+                '<?php
+
+                    final class Handler
+                    {
+                        /**
+                         * @var class-string<Throwable>[]
+                         */
+                        private array $dontReport = [];
+
+                        /**
+                         * @param class-string<Throwable> $throwable
+                         */
+                        public function dontReport(string $throwable): void
+                        {
+                            $this->dontReport[] = $throwable;
+                        }
+
+                        public function shouldReport(Throwable $t): bool
+                        {
+                            foreach ($this->dontReport as $tc) {
+                                if ($t instanceof $tc) {
+                                    return false;
+                                }
+                            }
+
+                            return true;
+                        }
+                    }
+
+                    $h = new Handler();
+                    $h->dontReport(RuntimeException::class);
+
+                    $h->shouldReport(new Exception());
+                    $h->shouldReport(new RuntimeException());'
+            ],
         ];
     }