From 5013a6480d989b48c9a910cfe3c4ad19f0508597 Mon Sep 17 00:00:00 2001
From: Sam Atkins <atkinssj@serenityos.org>
Date: Wed, 1 Dec 2021 21:05:13 +0000
Subject: [PATCH] AK: Mark smart pointer classes as [[nodiscard]]

This makes it an error to not do something with a returned smart
pointer, which should help prevent mistakes. In cases where you do need
to ignore the value, casting to void will placate the compiler.

I did have to add comments to disable clang-format on a couple of lines,
where it wanted to format the code like this:

```c++
private : NonnullRefPtr() = delete;
```
---
 AK/NonnullOwnPtr.h | 2 +-
 AK/NonnullRefPtr.h | 5 ++++-
 AK/OwnPtr.h        | 2 +-
 AK/RefPtr.h        | 2 +-
 AK/WeakPtr.h       | 2 +-
 5 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/AK/NonnullOwnPtr.h b/AK/NonnullOwnPtr.h
index 1645a0009d..8121467e5b 100644
--- a/AK/NonnullOwnPtr.h
+++ b/AK/NonnullOwnPtr.h
@@ -25,7 +25,7 @@ template<typename T>
 class WeakPtr;
 
 template<typename T>
-class NonnullOwnPtr {
+class [[nodiscard]] NonnullOwnPtr {
 public:
     using ElementType = T;
 
diff --git a/AK/NonnullRefPtr.h b/AK/NonnullRefPtr.h
index 7f9a0d00c2..4640518c2a 100644
--- a/AK/NonnullRefPtr.h
+++ b/AK/NonnullRefPtr.h
@@ -39,7 +39,7 @@ ALWAYS_INLINE void unref_if_not_null(T* ptr)
 }
 
 template<typename T>
-class NonnullRefPtr {
+class [[nodiscard]] NonnullRefPtr {
     template<typename U, typename P>
     friend class RefPtr;
     template<typename U>
@@ -218,8 +218,11 @@ public:
         AK::swap(m_ptr, other.m_ptr);
     }
 
+    // clang-format off
 private:
     NonnullRefPtr() = delete;
+    // clang-format on
+
     ALWAYS_INLINE RETURNS_NONNULL T* as_nonnull_ptr() const
     {
         VERIFY(m_ptr);
diff --git a/AK/OwnPtr.h b/AK/OwnPtr.h
index b950076efc..fe1494bf8d 100644
--- a/AK/OwnPtr.h
+++ b/AK/OwnPtr.h
@@ -15,7 +15,7 @@
 namespace AK {
 
 template<typename T>
-class OwnPtr {
+class [[nodiscard]] OwnPtr {
 public:
     OwnPtr() = default;
 
diff --git a/AK/RefPtr.h b/AK/RefPtr.h
index 41fe032d2b..5d3acff198 100644
--- a/AK/RefPtr.h
+++ b/AK/RefPtr.h
@@ -27,7 +27,7 @@ template<typename T>
 class OwnPtr;
 
 template<typename T, typename PtrTraits>
-class RefPtr {
+class [[nodiscard]] RefPtr {
     template<typename U, typename P>
     friend class RefPtr;
     template<typename U>
diff --git a/AK/WeakPtr.h b/AK/WeakPtr.h
index 69c36d2428..f31004f7cd 100644
--- a/AK/WeakPtr.h
+++ b/AK/WeakPtr.h
@@ -15,7 +15,7 @@
 namespace AK {
 
 template<typename T>
-class WeakPtr {
+class [[nodiscard]] WeakPtr {
     template<typename U>
     friend class Weakable;