From e6cab7826a010b34670e825650167b0d975d5819 Mon Sep 17 00:00:00 2001
From: Johannes Stoelp <johannes.stoelp@gmail.com>
Date: Tue, 1 Aug 2023 23:36:27 +0200
Subject: c++: fix option example by laundering returned ptr

---
 src/development/c++/fwd-perfect.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'src/development/c++')

diff --git a/src/development/c++/fwd-perfect.cc b/src/development/c++/fwd-perfect.cc
index 2fafc3e..15bf2b4 100644
--- a/src/development/c++/fwd-perfect.cc
+++ b/src/development/c++/fwd-perfect.cc
@@ -54,7 +54,11 @@ struct option {
 
     constexpr T& value() {
         assert(m_has_val);
-        return *reinterpret_cast<T*>(m_val);
+        // Placement new starts a new lifetime, launder pointer returned to the
+        // aligned storage.
+        //
+        // [1] https://en.cppreference.com/w/cpp/utility/launder
+        return *__builtin_launder(reinterpret_cast<T*>(m_val));
     }
 
   private:
-- 
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