Merge branch 'development' of https://github.com/ETLCPP/etl into development

include/etl/alignment.h

@@ -451,8 +451,9 @@ namespace etl
     reference create(TArgs&&... args) ETL_NOEXCEPT_EXPR(ETL_NOT_USING_EXCEPTIONS)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (&storage.value) value_type(etl::forward<TArgs>(args)...);
       valid = true;
-      return *::new (&storage.value) value_type(etl::forward<TArgs>(args)...);
+      return *p;
     }
 #else
     //***************************************************************************
@@ -463,8 +464,9 @@ namespace etl
     reference create(const T1& t1)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (&storage.value) value_type(t1);
       valid = true;
-      return *::new (&storage.value) value_type(t1);
+      return *p;
     }
 
     //***************************************************************************
@@ -475,8 +477,9 @@ namespace etl
     reference create(const T1& t1, const T2& t2)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (&storage.value) value_type(t1, t2);
       valid = true;
-      return *::new (&storage.value) value_type(t1, t2);
+      return *p;
     }
 
     //***************************************************************************
@@ -487,8 +490,9 @@ namespace etl
     reference create(const T1& t1, const T2& t2, const T3& t3)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (&storage.value) value_type(t1, t2, t3);
       valid = true;
-      return *::new (&storage.value) value_type(t1, t2, t3);
+      return *p;
     }
 
     //***************************************************************************
@@ -499,8 +503,9 @@ namespace etl
     reference create(const T1& t1, const T2& t2, const T3& t3, const T4& t4)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (&storage.value) value_type(t1, t2, t3, t4);
       valid = true;
-      return *::new (&storage.value) value_type(t1, t2, t3, t4);
+      return *p;
     }
 #endif
 
@@ -559,7 +564,7 @@ namespace etl
 
     struct dummy_t {};
 
-    //*******************************
+   //*******************************
     union union_type
     {
       union_type() ETL_NOEXCEPT
@@ -644,6 +649,7 @@ namespace etl
       , valid(false)
     {
       ETL_ASSERT(etl::is_aligned(pbuffer_, etl::alignment_of<T>::value), ETL_ERROR(etl::alignment_error));
+      create(t1);
     }
 
     //***************************************************************************
@@ -704,62 +710,67 @@ namespace etl
 #if ETL_USING_CPP11
     //***************************************************************************
     /// Constructs the instance of T forwarding the given \p args to its constructor.
-    /// \returns the instance of T which has been constructed in the internal byte array.
+    /// \returns the instance of T which has been constructed in the external buffer.
     //***************************************************************************
     template <typename... TArgs>
     reference create(TArgs&&... args) ETL_NOEXCEPT_EXPR(ETL_NOT_USING_EXCEPTIONS)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (pbuffer) value_type(etl::forward<TArgs>(args)...);
       valid = true;
-      return *::new (pbuffer) value_type(etl::forward<TArgs>(args)...);
+      return *p;
     }
 #else
     //***************************************************************************
     /// Constructs the instance of T with type T1
-    /// \returns the instance of T which has been constructed in the internal byte array.
+    /// \returns the instance of T which has been constructed in the external buffer.
     //***************************************************************************
     template <typename T1>
     reference create(const T1& t1)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (pbuffer) value_type(t1);
       valid = true;
-      return *::new (pbuffer) value_type(t1);
+      return *p;
     }
 
     //***************************************************************************
     /// Constructs the instance of T with types T1, T2
-    /// \returns the instance of T which has been constructed in the internal byte array.
+    /// \returns the instance of T which has been constructed in the external buffer.
     //***************************************************************************
     template <typename T1, typename T2>
     reference create(const T1& t1, const T2& t2)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (pbuffer) value_type(t1, t2);
       valid = true;
-      return *::new (pbuffer) value_type(t1, t2);
+      return *p;
     }
 
     //***************************************************************************
     /// Constructs the instance of T with types T1, T2, T3
-    /// \returns the instance of T which has been constructed in the internal byte array.
+    /// \returns the instance of T which has been constructed in the external buffer.
     //***************************************************************************
     template <typename T1, typename T2, typename T3>
     reference create(const T1& t1, const T2& t2, const T3& t3)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (pbuffer) value_type(t1, t2, t3);
       valid = true;
-      return *::new (pbuffer) value_type(t1, t2, t3);
+      return *p;
     }
 
     //***************************************************************************
     /// Constructs the instance of T with types T1, T2, T3, T4
-    /// \returns the instance of T which has been constructed in the internal byte array.
+    /// \returns the instance of T which has been constructed in the external buffer.
     //***************************************************************************
     template <typename T1, typename T2, typename T3, typename T4>
     reference create(const T1& t1, const T2& t2, const T3& t3, const T4& t4)
     {
       ETL_ASSERT(!has_value(), ETL_ERROR(etl::typed_storage_error));
+      pointer p = ::new (pbuffer) value_type(t1, t2, t3, t4);
       valid = true;
-      return *::new (pbuffer) value_type(t1, t2, t3, t4);
+      return *p;
     }
 #endif
 

include/etl/optional.h

@@ -536,6 +536,17 @@ namespace etl
 
         return storage.u.value;
       }
+
+      //*************************************************************************
+      /// Emplaces with zero arguments, i.e. default construct emplace.
+      //*************************************************************************
+      ETL_CONSTEXPR20_STL
+      T& emplace()
+      {
+        storage.construct();
+
+        return storage.u.value;
+      }
 #else
       //*************************************************************************
       /// Emplaces a value.

test/test_alignment.cpp

@@ -48,6 +48,7 @@ void f(int)
 {
 }
 
+// Demonstrator class for etl::typed_storage tests
 struct A_t
 {
   A_t(uint32_t v_x, uint8_t v_y)
@@ -56,13 +57,22 @@ struct A_t
   {
   }
 
+  // Just for test purpose. In production code, etl::typed_storage
+  // actually supports the use case of destructors being optimized
+  // away since they are not necessary for global objects that are
+  // never destroyed
   ~A_t()
   {
     x = 0;
     y = 0;
   }
 
-  bool operator==(A_t& other)
+  // etl::typed_storage helps implementing the use case of becoming
+  // independent of the destructor. By deleting the assignment operator,
+  // we make sure that the destructor is not linked
+  A_t& operator=(const A_t&) = delete;
+
+  bool operator==(const A_t& other) const
   {
     return other.x == x && other.y == y;
   }

test/test_optional.cpp

@@ -218,15 +218,27 @@ namespace
     }
 
     //*************************************************************************
-    TEST(test_emplace_zero_parameters)
+    TEST(test_emplace_zero_parameters_fundamental)
     {
       etl::optional<std::uint8_t> result = 1;
-      result.emplace();
+      CHECK_EQUAL(0, static_cast<int>(result.emplace()));
 
       CHECK_TRUE(result.has_value());
       CHECK_EQUAL(0, int(result.value()));
     }
 
+    //*************************************************************************
+    TEST(test_emplace_zero_parameters_non_fundamental)
+    {
+      etl::optional<std::string> result = std::string("abc");
+
+      std::string& ref = result.emplace();
+      CHECK_EQUAL(std::string(), ref);
+      CHECK_EQUAL(&ref, &result.value());
+      CHECK_TRUE(result.has_value());
+      CHECK_EQUAL("", std::string(result.value()));
+    }
+
     //*************************************************************************
     TEST(test_emplace_return)
     {