Merge branch 'feature/#615-addition-of-etl--expected' of https://gith…

…ub.com/ETLCPP/etl into feature/#615-addition-of-etl--expected

# Conflicts:
#	arduino/library-arduino.json
#	arduino/library-arduino.properties
#	include/etl/expected.h
#	include/etl/private/variant_variadic.h
#	include/etl/result.h
#	include/etl/version.h
#	library.json
#	library.properties
#	support/Release notes.txt
#	version.txt

.gitignore

@@ -363,8 +363,8 @@ examples/ArmTimerCallbacks - C++/ArmTimerCallbacks.uvoptx
 test/vs2022/.vs
 test/vs2022/random_clcg.csv
 test/vs2022/random_hash.csv
-test/vs2022/random_lcg.csv
 test/vs2022/random_lsfr.csv
+test/vs2022/random_lcg.csv
 test/vs2022/random_mwc.csv
 test/vs2022/random_pcg.csv
 test/vs2022/random_xorshift.csv

include/etl/result.h

@@ -470,6 +470,120 @@ namespace etl
     }
 #endif
 
+  private:
+
+    etl::optional<TError> data;
+  };
+
+  //*****************************************************************************
+  /// Result type.
+  /// Specialisation for void error type.
+  //*****************************************************************************
+  template<typename TValue>
+  class result<TValue, void>
+  {
+  public:
+
+    //*******************************************
+    /// Default Constructor
+    //*******************************************
+    result()
+    {
+    }
+
+    //*******************************************
+    /// Copy constructor
+    //*******************************************
+    result(const result& other)
+      : data(other.data)
+    {
+    }
+
+    //*******************************************
+    /// Move constructor
+    //*******************************************
+    result(result&& other)
+      : data(etl::move(other.data))
+    {
+    }
+
+    //*******************************************
+    /// Construct from error
+    //*******************************************
+    result(const TValue& value)
+      : data(value)
+    {
+    }
+
+    //*******************************************
+    /// Move construct from error
+    //*******************************************
+    result(TValue&& value)
+      : data(etl::move(value))
+    {
+    }
+
+    //*******************************************
+    /// Copy assign from error
+    //*******************************************
+    result& operator =(const TValue& value)
+    {
+      data = value;
+      return *this;
+    }
+
+    //*******************************************
+    /// Move assign from error
+    //*******************************************
+    result& operator =(TValue&& value)
+    {
+      data = etl::move(value);
+      return *this;
+    }
+
+    //*******************************************
+    /// <b>true</b> if result contains a value
+    //*******************************************
+    bool has_value() const
+    {
+      return data.has_value();
+    }
+
+    //*******************************************
+    /// <b>true</b> if result contains a value
+    //*******************************************
+    bool is_value() const
+    {
+      return has_value();
+    }
+
+    //*******************************************
+    /// <b>true</b> if result contains an error
+    //*******************************************
+    bool is_error() const
+    {
+      return !has_value();
+    }
+
+    //*******************************************
+    /// Returns a const reference to the error.
+    /// Undefined if the result does not contain an error.
+    //*******************************************
+    const TValue& value() const
+    {
+      return data.value();
+    }
+
+    //*******************************************
+    /// Returns an rvalue reference to the error.
+    /// Undefined if the result does not contain an error.
+    //*******************************************
+    TValue&& value()
+    {
+      return etl::move(data.value());
+    }
+#endif
+
   private:
 
     etl::optional<TValue> data;