From 376b956214b87fbf6f5c71a8ebf6c4b1f1f10bf3 Mon Sep 17 00:00:00 2001
From: Daniel Bertalan <dani@danielbertalan.dev>
Date: Wed, 5 Jun 2024 23:52:33 +0200
Subject: [PATCH] Tests: Stop invoking UB in `AK::NeverDestroyed`'s tests

Instead of attempting a stack use-after-free by reading an out-of-scope
object's data member, let's keep a flag that checks if the destructor
had been called in the outer scope.

Fixes #64
---
 Tests/AK/TestNeverDestroyed.cpp | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/Tests/AK/TestNeverDestroyed.cpp b/Tests/AK/TestNeverDestroyed.cpp
index 43ea3e65f63..d212ccaf7fd 100644
--- a/Tests/AK/TestNeverDestroyed.cpp
+++ b/Tests/AK/TestNeverDestroyed.cpp
@@ -44,20 +44,27 @@ TEST_CASE(should_construct_by_move)
     EXPECT_EQ(1, n->num_moves);
 }
 
-NO_SANITIZE_ADDRESS static void should_not_destroy()
-{
-    Counter* c = nullptr;
+struct DestructorChecker {
+    DestructorChecker(bool& destroyed)
+        : m_destroyed(destroyed)
     {
-        AK::NeverDestroyed<Counter> n {};
-        // note: explicit stack-use-after-scope
-        c = &n.get();
     }
-    EXPECT_EQ(0, c->num_destroys);
-}
+
+    ~DestructorChecker()
+    {
+        m_destroyed = true;
+    }
+
+    bool& m_destroyed;
+};
 
 TEST_CASE(should_not_destroy)
 {
-    should_not_destroy();
+    bool destroyed = false;
+    {
+        AK::NeverDestroyed<DestructorChecker> n(destroyed);
+    }
+    EXPECT(!destroyed);
 }
 
 TEST_CASE(should_provide_dereference_operator)