diff --git a/src/main/java/com/eprosima/fastcdr/idl/templates/FastCdrCommon.stg b/src/main/java/com/eprosima/fastcdr/idl/templates/FastCdrCommon.stg
index 12bc5f26..0f8f316d 100644
--- a/src/main/java/com/eprosima/fastcdr/idl/templates/FastCdrCommon.stg
+++ b/src/main/java/com/eprosima/fastcdr/idl/templates/FastCdrCommon.stg
@@ -59,3 +59,13 @@ member_array_cstring_destructor(ctx, name, loopvar, dims) ::= <<$if(rest(dims))$
 {
     free(str);
 }$endif$>>
+
+member_default_init(member) ::= <%
+$if(member.annotationDefault)$
+ {$member.annotationDefaultValue$}
+$elseif(!member.annotationOptional && !member.annotationExternal)$
+$if(member.typecode.initialValue)$
+ {$member.typecode.initialValue$}
+$endif$
+$endif$
+%>
diff --git a/src/main/java/com/eprosima/fastcdr/idl/templates/TypesHeader.stg b/src/main/java/com/eprosima/fastcdr/idl/templates/TypesHeader.stg
index 675a88b3..93200dbe 100644
--- a/src/main/java/com/eprosima/fastcdr/idl/templates/TypesHeader.stg
+++ b/src/main/java/com/eprosima/fastcdr/idl/templates/TypesHeader.stg
@@ -30,6 +30,9 @@ $if(ctx.thereIsBitset)$
 #include <bitset>
 $endif$
 #include <cstdint>
+$if(ctx.thereIsUnion)$
+#include <functional>
+$endif$
 $if(ctx.thereIsMap)$
 #include <map>
 $endif$
@@ -295,10 +298,8 @@ public:
      */
     eProsima_user_DllExport $union.name$()
     {
-        $if(union.defaultvalue)$
-        m__d = $union.defaultvalue$;
-        $else$
-        m__d = $first(first(union.members).labels)$;
+        $if(union.defaultMember)$
+        $union.defaultMember.name$_();
         $endif$
     }
 
@@ -307,6 +308,10 @@ public:
      */
     eProsima_user_DllExport ~$union.name$()
     {
+        if (member_destructor_)
+        {
+            member_destructor_();
+        }
     }
 
     /*!
@@ -318,10 +323,13 @@ public:
     {
         m__d = x.m__d;
 
-        switch (m__d)
+        switch (x.selected_member_)
         {
-            $union.members:{ member | $unionmember_copy(member)$}; separator="\n"$
-            $unionmemberdefault_copy(union.defaultMember)$
+            $union.members:{ member |
+            case $member.id$:
+                $member.name$_() = x.m_$member.name$;
+                break;
+            }; separator="\n"$
         }
     }
 
@@ -334,10 +342,13 @@ public:
     {
         m__d = x.m__d;
 
-        switch (m__d)
+        switch (x.selected_member_)
         {
-            $union.members:{ member | $unionmember_move(member)$}; separator="\n"$
-            $unionmemberdefault_move(union.defaultMember)$
+            $union.members:{ member |
+            case $member.id$:
+                $member.name$_() = std::move(x.m_$member.name$);
+                break;
+            }; separator="\n"$
         }
     }
 
@@ -350,10 +361,13 @@ public:
     {
         m__d = x.m__d;
 
-        switch (m__d)
+        switch (x.selected_member_)
         {
-            $union.members:{ member | $unionmember_copy(member)$}; separator="\n"$
-            $unionmemberdefault_copy(union.defaultMember)$
+            $union.members:{ member |
+            case $member.id$:
+                $member.name$_() = x.m_$member.name$;
+                break;
+            }; separator="\n"$
         }
 
         return *this;
@@ -368,10 +382,13 @@ public:
     {
         m__d = x.m__d;
 
-        switch (m__d)
+        switch (x.selected_member_)
         {
-            $union.members:{ member | $unionmember_move(member)$}; separator="\n"$
-            $unionmemberdefault_move(union.defaultMember)$
+            $union.members:{ member |
+            case $member.id$:
+                $member.name$_() = std::move(x.m_$member.name$);
+                break;
+            }; separator="\n"$
         }
 
         return *this;
@@ -384,19 +401,22 @@ public:
     eProsima_user_DllExport bool operator ==(
             const $union.name$& x) const
     {
-        if (m__d != x.m__d)
-        {
-            return false;
-        }
+        bool ret_value {false};
 
-        switch (m__d)
+        if (m__d == x.m__d &&
+                selected_member_ == x.selected_member_)
         {
-            $union.members:{ member | $unionmember_compare(member)$}; separator="\n"$
-            $unionmemberdefault_compare(union.defaultMember)$
+            switch (selected_member_)
+            {
+                $union.members:{ member |
+                case $member.id$:
+                    ret_value = (m_$member.name$ == x.m_$member.name$);
+                    break;
+                }; separator="\n"$
+            }
         }
-        $if(!union.defaultMember)$
-        return false;
-        $endif$
+
+        return ret_value;
     }
 
     /*!
@@ -417,18 +437,24 @@ public:
     eProsima_user_DllExport void _d(
             $union.discriminator.typecode.cppTypename$ __d)
     {
-        bool b = false;
+        bool valid_discriminator = false;
 
-        switch (m__d)
+        switch (__d)
         {
-            $union.members:{ member | $unionmember_discriminator_case(member=member, totallabels=union.totallabels)$}; separator="\n"$
-            $if(!union.defaultMember)$
+            $union.members:{ member |
+            $member.labels:{ label | case $label$:}; separator="\n"$
+            $if(member.default)$
             default:
-                break;
             $endif$
+                if ($member.id$ == selected_member_)
+                {
+                    valid_discriminator = true;
+                \}
+                break;
+            }; separator="\n"$
         }
 
-        if (!b)
+        if (!valid_discriminator)
         {
             throw eprosima::fastcdr::exception::BadParamException("Discriminator doesn't correspond with the selected union member");
         }
@@ -445,24 +471,58 @@ public:
         return m__d;
     }
 
-    /*!
-     * @brief This function returns a reference to the discriminator.
-     * @return Reference to the discriminator.
-     */
-    eProsima_user_DllExport $union.discriminator.typecode.cppTypename$& _d()
+    $union.members: { member | $public_union_member_declaration(union, member)$}; separator="\n"$
+
+    $if(!union.defaultMember)$
+    void _default()
     {
-        return m__d;
-    }
+        if (member_destructor_)
+        {
+            member_destructor_();
+        }
 
-    $union.members:{ member | $public_unionmember_declaration(union, member)$}; separator="\n"$
+        selected_member_ = 0x0FFFFFFFu;
+    }
+    $endif$
 
     $extensions : {extension | $extension$}; separator="\n"$
 
 private:
 
-    $union.discriminator.typecode.cppTypename$ m__d;
+    $union.members: { member |
+        $member_type_declaration(member)$& $member.name$_()
+        {
+            if ($member.id$ != selected_member_)
+            {
+                if (member_destructor_)
+                {
+                    member_destructor_();
+                \}
+
+                selected_member_ = $member.id$;
+                $if(member.typecode.primitive)$
+                member_destructor_ = nullptr;
+                m_$member.name$ = $member_default_init(member)$;
+                $else$
+                member_destructor_ = [&]() {$union_member_destroy_call(member)$\};
+                new(&m_$member.name$) $member_type_declaration(member)$();
+                $endif$;
+            \}
+
+            return m_$member.name$;
+        \}
+    }; separator="\n"$
+
+    $union.discriminator.typecode.cppTypename$ m__d {$union.defaultvalue$};
+
+    union
+    {
+        $union.members:{ member | $union_member_declaration(member=member)$}; separator="\n"$
+    };
+
+    uint32_t selected_member_ {0x0FFFFFFFu};
 
-    $union.members:{ member | $private_member_declaration(member=member)$}; separator="\n"$
+    std::function<void()> member_destructor_;
 };
 >>
 
@@ -775,17 +835,17 @@ private_member_declaration(member) ::= <<
 $member_type_declaration(member)$ m_$member.name$$member_default_init(member)$;
 >>
 
-public_unionmember_declaration(union, member) ::= <<
+public_union_member_declaration(union, member) ::= <<
 $if(member.annotationExternal)$
-$public_unionmember_common_declaration(union, member)$
+$public_union_member_common_declaration(union, member)$
 $elseif(member.typecode.primitive)$
-$public_unionmember_primitive_declaration(union, member)$
+$public_union_member_primitive_declaration(union, member)$
 $else$
-$public_unionmember_common_declaration(union, member)$
+$public_union_member_common_declaration(union, member)$
 $endif$
 >>
 
-public_unionmember_primitive_declaration(union, member) ::= <<
+public_union_member_primitive_declaration(union, member) ::= <<
 /*!
  * @brief This function sets a value in member $member.name$
  * @param _$member.name$ New value for member $member.name$
@@ -793,8 +853,8 @@ public_unionmember_primitive_declaration(union, member) ::= <<
 eProsima_user_DllExport void $member.name$(
         $member.typecode.cppTypename$ _$member.name$)
 {
-    m_$member.name$ = _$member.name$;
-    $unionmember_set_discriminator(member=member, defaultvalue=union.defaultvalue)$
+    $member.name$_() = _$member.name$;
+    $union_member_set_discriminator(member=member, defaultvalue=union.defaultvalue)$
 }
 
 /*!
@@ -804,7 +864,10 @@ eProsima_user_DllExport void $member.name$(
  */
 eProsima_user_DllExport $member.typecode.cppTypename$ $member.name$() const
 {
-    $unionmember_check_case_list(member=member, totallabels=union.totallabels)$
+    if ($member.id$ != selected_member_)
+    {
+        throw eprosima::fastcdr::exception::BadParamException("This member has not been selected");
+    }
 
     return m_$member.name$;
 }
@@ -816,13 +879,16 @@ eProsima_user_DllExport $member.typecode.cppTypename$ $member.name$() const
  */
 eProsima_user_DllExport $member.typecode.cppTypename$& $member.name$()
 {
-    $unionmember_check_case_list(member=member, totallabels=union.totallabels)$
+    if ($member.id$ != selected_member_)
+    {
+        throw eprosima::fastcdr::exception::BadParamException("This member has not been selected");
+    }
 
     return m_$member.name$;
 }
 >>
 
-public_unionmember_common_declaration(union, member) ::= <<
+public_union_member_common_declaration(union, member) ::= <<
 /*!
  * @brief This function copies the value in member $member.name$
  * @param _$member.name$ New value to be copied in member $member.name$
@@ -830,8 +896,8 @@ public_unionmember_common_declaration(union, member) ::= <<
 eProsima_user_DllExport void $member.name$(
         const $member_type_declaration(member)$& _$member.name$)
 {
-    m_$member.name$ = _$member.name$;
-    $unionmember_set_discriminator(member=member, defaultvalue=union.defaultvalue)$
+    $member.name$_() = _$member.name$;
+    $union_member_set_discriminator(member=member, defaultvalue=union.defaultvalue)$
 }
 
 /*!
@@ -841,8 +907,8 @@ eProsima_user_DllExport void $member.name$(
 eProsima_user_DllExport void $member.name$(
         $member_type_declaration(member)$&& _$member.name$)
 {
-    m_$member.name$ = std::move(_$member.name$);
-    $unionmember_set_discriminator(member=member, defaultvalue=union.defaultvalue)$
+    $member.name$_() = _$member.name$;
+    $union_member_set_discriminator(member=member, defaultvalue=union.defaultvalue)$
 }
 
 /*!
@@ -852,7 +918,10 @@ eProsima_user_DllExport void $member.name$(
  */
 eProsima_user_DllExport const $member_type_declaration(member)$& $member.name$() const
 {
-    $unionmember_check_case_list(member=member, totallabels=union.totallabels)$
+    if ($member.id$ != selected_member_)
+    {
+        throw eprosima::fastcdr::exception::BadParamException("This member has not been selected");
+    }
 
     return m_$member.name$;
 }
@@ -864,22 +933,15 @@ eProsima_user_DllExport const $member_type_declaration(member)$& $member.name$()
  */
 eProsima_user_DllExport $member_type_declaration(member)$& $member.name$()
 {
-    $unionmember_check_case_list(member=member, totallabels=union.totallabels)$
+    if ($member.id$ != selected_member_)
+    {
+        throw eprosima::fastcdr::exception::BadParamException("This member has not been selected");
+    }
 
     return m_$member.name$;
 }
 >>
 
-member_default_init(member) ::= <%
-$if(member.annotationDefault)$
- {$member.annotationDefaultValue$}
-$elseif(!member.annotationOptional && !member.annotationExternal)$
-$if(member.typecode.initialValue)$
- {$member.typecode.initialValue$}
-$endif$
-$endif$
-%>
-
 member_move(member) ::= <%
 $if(member.typecode.primitive)$
 m_$member.name$ = x.m_$member.name$;
@@ -888,137 +950,38 @@ m_$member.name$ = std::move(x.m_$member.name$);
 $endif$
 %>
 
-unionmember_discriminator_case(member, totallabels) ::= <<
-$if(member.default)$
-default:
-    b = true;
-    switch (__d)
-    {
-        $totallabels:{ label | case $label$:}; separator="\n"$
-            b = false;
-            break;
-        default:
-            break;
-    }
-    break;
-$else$
-$member.labels:{ label | case $label$:}; separator="\n"$
-    switch (__d)
-    {
-        $member.labels:{ label | case $label$:}; separator="\n"$
-            b = true;
-            break;
-        default:
-            break;
-    }
-    break;
-$endif$
->>
-
-unionmember_copy(member) ::= <<
-$if(member.labels)$
-$member.labels:{ label | case $label$:}; separator="\n"$
-    m_$member.name$ = x.m_$member.name$;
-    break;
-$endif$
+union_member_declaration(member) ::= <<
+$member_type_declaration(member)$ m_$member.name$;
 >>
 
-unionmemberdefault_copy(member) ::= <<
-default:
-$if(member)$
-$if(member.default)$
-    m_$member.name$ = x.m_$member.name$;
-$endif$
-$endif$
-
-    break;
->>
-
-unionmember_move(member) ::= <<
-$if(member.labels)$
-$member.labels:{ label | case $label$:}; separator="\n"$
-$if(member.typecode.primitive)$
-    m_$member.name$ = x.m_$member.name$;
+union_member_destroy_call(member) ::= <%
+m_$member.name$.
+$if(member.annotationExternal)$
+~external();
+$elseif(!member.typecode.isAliasType && (member.typecode.isStringType || member.typecode.isWStringType))$
+$if(member.typecode.isBounded && member.typecode.isStringType)$
+~fixed_string();
 $else$
-    m_$member.name$ = std::move(x.m_$member.name$);
-$endif$
-
-    break;
-$endif$
->>
-
-unionmemberdefault_move(member) ::= <<
-default:
-$if(member)$
-$if(member.default)$
-$if(member.typecode.primitive)$
-    m_$member.name$ = x.m_$member.name$;
+~basic_string();
+$endif$
+$elseif(!member.typecode.isAliasType && member.typecode.isSequenceType)$
+~vector();
+$elseif(!member.typecode.isAliasType && member.typecode.isArrayType)$
+~array();
+$elseif(!member.typecode.isAliasType && member.typecode.isMapType)$
+~map();
 $else$
-    m_$member.name$ = std::move(x.m_$member.name$);
-$endif$
-$endif$
-$endif$
-
-    break;
->>
-
-unionmember_compare(member) ::= <<
-$if(member.labels)$
-$member.labels:{ label | case $label$:}; separator="\n"$
-    return (m_$member.name$ == x.m_$member.name$);
-    break;
+~$member.typecode.noScopedCppTypename$();
 $endif$
->>
-
-unionmemberdefault_compare(member) ::= <<
-default:
-$if(member)$
-$if(member.default)$
-    return m_$member.name$ == x.m_$member.name$;
-$endif$
-$endif$
-
-    break;
->>
+%>
 
-unionmember_set_discriminator(member, defaultvalue) ::= <<
+union_member_set_discriminator(member, defaultvalue) ::= <%
 $if(member.default)$
 m__d = $defaultvalue$;
 $else$
 m__d = $first(member.labels)$;
 $endif$
->>
-
-unionmember_check_case_list(member, totallabels) ::= <<
-$if(member.default)$
-bool b = true;
-
-switch (m__d)
-{
-    $totallabels:{ label | case $label$:}; separator="\n"$
-        b = false;
-        break;
-    default:
-        break;
-}
-$else$
-bool b = false;
-
-switch (m__d)
-{
-    $member.labels:{ label | case $label$:}; separator="\n"$
-        b = true;
-        break;
-    default:
-        break;
-}
-$endif$
-
-if (!b)
-{
-    throw eprosima::fastcdr::exception::BadParamException("This member has not been selected");
-}
->>
+%>
 
 //{ Fast DDS-Gen extensions
 module_conversion(ctx, parent, modules, definition_list) ::= <<
diff --git a/src/main/java/com/eprosima/fastdds/idl/templates/TypesCdrAuxHeaderImpl.stg b/src/main/java/com/eprosima/fastdds/idl/templates/TypesCdrAuxHeaderImpl.stg
index 4f2ab62d..8f597fe6 100644
--- a/src/main/java/com/eprosima/fastdds/idl/templates/TypesCdrAuxHeaderImpl.stg
+++ b/src/main/java/com/eprosima/fastdds/idl/templates/TypesCdrAuxHeaderImpl.stg
@@ -15,6 +15,7 @@
 group TypesCdrAuxHeader;
 
 import "eprosima.stg"
+import "com/eprosima/fastcdr/idl/templates/FastCdrCommon.stg"
 
 main(ctx, definitions, extensions) ::= <<
 $fileHeader(ctx=ctx, file=[ctx.filename, "CdrAux.ipp"], description=["This source file contains some declarations of CDR related functions."])$
@@ -251,12 +252,12 @@ eProsima_user_DllExport size_t calculate_serialized_size(
 
     switch (data._d())
     {
-        $union.membersDefaultAtEnd:{ member | $if(member.printable)$$member.labels:{ label |case $label$:}; separator="\n"$
+        $union.members :{ member |
+        $member.labels:{ label |case $label$:}; separator="\n"$
         $if(member.default)$default:$endif$
             calculated_size += calculator.calculate_member_serialized_size(eprosima::fastcdr::MemberId($if(union.annotationMutable)$$member.id$$else$$member.index$$endif$),
                         data.$member.name$(), current_alignment);
             break;
-        $endif$
         }; separator="\n"$
         $if(!union.defaultMember)$
         default:
@@ -291,12 +292,11 @@ eProsima_user_DllExport void serialize(
 
     switch (data._d())
     {
-        $union.membersDefaultAtEnd:{ member | $if(member.printable)$
+        $union.members :{ member |
         $member.labels:{ label |case $label$:}; separator="\n"$
         $if(member.default)$default:$endif$
             scdr << eprosima::fastcdr::MemberId($if(union.annotationMutable)$$member.id$$else$$member.index$$endif$) << data.$member.name$();
             break;
-        $endif$
         }; separator="\n"$
         $if(!union.defaultMember)$
         default:
@@ -322,34 +322,52 @@ eProsima_user_DllExport void deserialize(
             [&data](eprosima::fastcdr::Cdr& dcdr, const eprosima::fastcdr::MemberId& mid) -> bool
             {
                 bool ret_value = true;
-                switch (mid.id)
+                if (0 == mid.id)
                 {
-                    case 0:
-                        dcdr \>> data._d();
-                        break;
-                    default:
-                        switch (data._d())
-                        {
-                            $union.membersDefaultAtEnd:{ member | $if(member.printable)$
-                            $member.labels:{ label |case $label$:}; separator="\n"$
-                            $if(member.default)$default:$endif$
-                                $if(union.annotationMutable || member.annotationOptional)$
-                                if (mid != $member.id$)
-                                {
-                                    throw BadParamException("Deserializing union member $member.name$ the MemberId doesn't match");
-                                \}
-                                $endif$
-                                dcdr \>> data.$member.name$();
-                                break;
-                            $endif$
-                            }; separator="\n"$
-                            $if(!union.defaultMember)$
-                            default:
+                    $union.discriminator.typecode.cppTypename$ discriminator;
+                    dcdr \>> discriminator;
+
+                    switch (discriminator)
+                    {
+                        $union.members:{ member |
+                        $member.labels:{ label |case $label$:}; separator="\n"$
+                        $if(member.default)$default:$endif$
+                            {
+                                $member_type_declaration(member)$ $member.name$_value$member_default_init(member)$;
+                                data.$member.name$(std::move($member.name$_value));
+                                data._d(discriminator);
                                 break;
+                            \}
+                        }; separator="\n"$
+                        $if(!union.defaultMember)$
+                        default:
+                            data._default();
+                            break;
+                        $endif$
+                    }
+                }
+                else
+                {
+                    switch (data._d())
+                    {
+                        $union.members :{ member |
+                        $member.labels:{ label |case $label$:}; separator="\n"$
+                        $if(member.default)$default:$endif$
+                            $if(union.annotationMutable || member.annotationOptional)$
+                            if (mid != $member.id$)
+                            {
+                                throw BadParamException("Deserializing union member $member.name$ the MemberId doesn't match");
+                            \}
                             $endif$
-                        }
-                        $if(!union.annotationMutable)$ret_value = false;$endif$
-                        break;
+                            dcdr \>> data.$member.name$();
+                            break;
+                        }; separator="\n"$
+                        $if(!union.defaultMember)$
+                        default:
+                            break;
+                        $endif$
+                    }
+                    $if(!union.annotationMutable)$ret_value = false;$endif$
                 }
                 return ret_value;
             });
diff --git a/thirdparty/dds-types-test b/thirdparty/dds-types-test
index 604460f6..ef234fb8 160000
--- a/thirdparty/dds-types-test
+++ b/thirdparty/dds-types-test
@@ -1 +1 @@
-Subproject commit 604460f658b0721cb4a6b5bf19bf157e2160676a
+Subproject commit ef234fb8071c0a93fee23a40537592df7e1778bc
diff --git a/thirdparty/idl-parser b/thirdparty/idl-parser
index c5a8f087..f3fdedfe 160000
--- a/thirdparty/idl-parser
+++ b/thirdparty/idl-parser
@@ -1 +1 @@
-Subproject commit c5a8f087ded0d3decd26e7a89db21b6b0d35563d
+Subproject commit f3fdedfeea7958afaf8808447923f886efb3a40e