From a0af0f94152201eb9777b4bf9222110de5448153 Mon Sep 17 00:00:00 2001
From: John Wellbelove <jwellbelove@users.noreply.github.com>
Date: Wed, 14 Jun 2023 09:14:44 +0100
Subject: [PATCH] Modified the POD specialisation to accept objects that have
 deleted default constructors

---
 include/etl/optional.h | 53 +++++++++++++++++++++++++++++-------------
 test/test_optional.cpp | 14 +++++++----
 2 files changed, 47 insertions(+), 20 deletions(-)

diff --git a/include/etl/optional.h b/include/etl/optional.h
index 47517b6c..2e28ff75 100644
--- a/include/etl/optional.h
+++ b/include/etl/optional.h
@@ -700,8 +700,8 @@ namespace etl
     //***************************************************************************
     ETL_CONSTEXPR14 optional(const T& value_)
       : valid(true)
-      , storage(value_)
     {
+      storage.u.value = value_;
     }
 
 #if ETL_USING_CPP11
@@ -710,8 +710,8 @@ namespace etl
     //***************************************************************************
     ETL_CONSTEXPR14 optional(T&& value_)
       : valid(true)
-      , storage(etl::move(value_))
     {
+      storage.u.value = etl::move(value_);
     }
 #endif
 
@@ -731,7 +731,7 @@ namespace etl
     {
       if (this != &other)
       {
-        storage = other.storage;
+        storage.u = other.storage.u;
         valid   = other.valid;
       }
 
@@ -746,7 +746,7 @@ namespace etl
     {
       if (this != &other)
       {
-        storage = etl::move(other.storage);
+        storage.u = etl::move(other.storage.u);
         valid   = other.valid;
       }
 
@@ -759,7 +759,7 @@ namespace etl
     //***************************************************************************
     ETL_CONSTEXPR14 optional& operator =(const T& value_)
     {
-      storage = value_;
+      storage.u.value = value_;
       valid = true;
 
       return *this;
@@ -771,7 +771,7 @@ namespace etl
     //***************************************************************************
     ETL_CONSTEXPR14 optional& operator =(T&& value_)
     {
-      storage = etl::move(value_);
+      storage.u.value = etl::move(value_);
       valid = true;
 
       return *this;
@@ -878,7 +878,7 @@ namespace etl
       ETL_ASSERT(valid, ETL_ERROR(optional_invalid));
 #endif
 
-      return storage;
+      return storage.u.value;
     }
 
     //***************************************************************************
@@ -890,7 +890,7 @@ namespace etl
       ETL_ASSERT(valid, ETL_ERROR(optional_invalid));
 #endif
 
-      return storage;
+      return storage.u.value;
     }
 
     //***************************************************************************
@@ -911,7 +911,7 @@ namespace etl
       ETL_ASSERT(valid, ETL_ERROR(optional_invalid));
 #endif
 
-      return etl::move(storage);
+      return etl::move(storage.u.value);
     }
 
     //***************************************************************************
@@ -923,7 +923,7 @@ namespace etl
       ETL_ASSERT(valid, ETL_ERROR(optional_invalid));
 #endif
 
-      return etl::move(storage);
+      return etl::move(storage.u.value);
     }
 
     //***************************************************************************
@@ -961,7 +961,7 @@ namespace etl
     template <typename ... Args>
     ETL_CONSTEXPR14 void emplace(Args && ... args)
     {
-      storage = T(ETL_OR_STD::forward<Args>(args)...);
+      storage.u.value = T(ETL_OR_STD::forward<Args>(args)...);
       valid = true;
     }
 #else
@@ -972,7 +972,7 @@ namespace etl
     template <typename T1>
     void emplace(const T1& value1)
     {
-      storage = value1;
+      storage.u.value = value1;
       valid = true;
     }
 
@@ -983,7 +983,7 @@ namespace etl
     template <typename T1, typename T2>
     void emplace(const T1& value1, const T2& value2)
     {
-      storage = T(value1, value2);
+      storage.u.value = T(value1, value2);
       valid = true;
     }
 
@@ -994,7 +994,7 @@ namespace etl
     template <typename T1, typename T2, typename T3>
     void emplace(const T1& value1, const T2& value2, const T3& value3)
     {
-      storage = T(value1, value2, value3);
+      storage.u.value = T(value1, value2, value3);
       valid = true;
     }
 
@@ -1005,7 +1005,7 @@ namespace etl
     template <typename T1, typename T2, typename T3, typename T4>
     void emplace(const T1& value1, const T2& value2, const T3& value3, const T4& value4)
     {
-      storage = T(value1, value2, value3, value4);
+      storage.u.value = T(value1, value2, value3, value4);
       valid = true;
     }
 #endif
@@ -1013,7 +1013,28 @@ namespace etl
   private:
 
     bool valid;
-    T    storage;
+
+    struct storage_type
+    {
+      storage_type()
+      {
+      }
+
+      union union_type
+      {
+        union_type()
+          : dummy(0)
+        {
+        }
+
+        char dummy;
+        T value;
+      };
+
+      union_type u;
+    };
+
+    storage_type storage;
   };
 
 #include "etl/private/diagnostic_uninitialized_push.h"
diff --git a/test/test_optional.cpp b/test/test_optional.cpp
index 8ca78f6b..e6a9a832 100644
--- a/test/test_optional.cpp
+++ b/test/test_optional.cpp
@@ -495,12 +495,18 @@ namespace
     }
 
     //*************************************************************************
-    TEST(test_optional_pod_assign_bug_714)
+    struct MyPODObject
     {
-      etl::optional<int> o = 42;
-      o = etl::nullopt;
+      MyPODObject() = delete;
+      int value;
+    };
 
-      CHECK_EQUAL(false, o.has_value());
+    TEST(test_optional_pod_emplace_bug_712)
+    {
+      etl::optional<MyPODObject> optionalObject; // The Test: Does this compile for an object with a deleted default constructor?
+
+      // Make sure it isn't optimised away.
+      CHECK_FALSE(optionalObject.has_value());
     }
   };
 }