From 163367da397e8597eebb732a02c10b2949d166a2 Mon Sep 17 00:00:00 2001
From: Andrew Kaster <akaster@serenityos.org>
Date: Sun, 31 Oct 2021 14:52:26 -0600
Subject: [PATCH] AK: Resolve clang-tidy warnings about unusual assignment
 operators

Either not returning *this, or in the case of Variant, not checking for
self assignment. In AK::Atomic, we can't return *this due to the wrapper
semantics Atomic implements.
---
 AK/Atomic.h  |  3 +++
 AK/Checked.h |  3 ++-
 AK/Variant.h | 20 ++++++++++++--------
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/AK/Atomic.h b/AK/Atomic.h
index e1a1007b2ed..70ae6d13990 100644
--- a/AK/Atomic.h
+++ b/AK/Atomic.h
@@ -187,6 +187,7 @@ public:
         return *ret;
     }
 
+    // NOLINTNEXTLINE(misc-unconventional-assign-operator) We want operator= to exchange the value, so returning an object of type Atomic& here does not make sense
     ALWAYS_INLINE T operator=(T desired) volatile noexcept
     {
         store(desired);
@@ -317,6 +318,7 @@ public:
         return __atomic_load_n(&m_value, order);
     }
 
+    // NOLINTNEXTLINE(misc-unconventional-assign-operator) We want operator= to exchange the value, so returning an object of type Atomic& here does not make sense
     ALWAYS_INLINE T operator=(T desired) volatile noexcept
     {
         store(desired);
@@ -417,6 +419,7 @@ public:
         return __atomic_load_n(&m_value, order);
     }
 
+    // NOLINTNEXTLINE(misc-unconventional-assign-operator) We want operator= to exchange the value, so returning an object of type Atomic& here does not make sense
     T* operator=(T* desired) volatile noexcept
     {
         store(desired);
diff --git a/AK/Checked.h b/AK/Checked.h
index bac072dfbec..feba84b3efc 100644
--- a/AK/Checked.h
+++ b/AK/Checked.h
@@ -138,7 +138,8 @@ public:
     template<typename U>
     constexpr Checked& operator=(U value)
     {
-        return *this = Checked(value);
+        *this = Checked(value);
+        return *this;
     }
 
     constexpr Checked& operator=(const Checked& other) = default;
diff --git a/AK/Variant.h b/AK/Variant.h
index dae5cd7272c..883fb2e5269 100644
--- a/AK/Variant.h
+++ b/AK/Variant.h
@@ -271,11 +271,13 @@ public:
         requires(!(IsTriviallyCopyConstructible<Ts> && ...) || !(IsTriviallyDestructible<Ts> && ...))
 #endif
     {
-        if constexpr (!(IsTriviallyDestructible<Ts> && ...)) {
-            Helper::delete_(m_index, m_data);
+        if (this != &other) {
+            if constexpr (!(IsTriviallyDestructible<Ts> && ...)) {
+                Helper::delete_(m_index, m_data);
+            }
+            m_index = other.m_index;
+            Helper::copy_(other.m_index, other.m_data, m_data);
         }
-        m_index = other.m_index;
-        Helper::copy_(other.m_index, other.m_data, m_data);
         return *this;
     }
 
@@ -284,11 +286,13 @@ public:
         requires(!(IsTriviallyMoveConstructible<Ts> && ...) || !(IsTriviallyDestructible<Ts> && ...))
 #endif
     {
-        if constexpr (!(IsTriviallyDestructible<Ts> && ...)) {
-            Helper::delete_(m_index, m_data);
+        if (this != &other) {
+            if constexpr (!(IsTriviallyDestructible<Ts> && ...)) {
+                Helper::delete_(m_index, m_data);
+            }
+            m_index = other.m_index;
+            Helper::move_(other.m_index, other.m_data, m_data);
         }
-        m_index = other.m_index;
-        Helper::move_(other.m_index, other.m_data, m_data);
         return *this;
     }