* Change C++ serialization/deserialization to not be move-only operations (with the except of |Ha…

mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl

Index: mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
index 48b76e5403800490cc49e7c930eebb72ada50323..25a3ee414af454bf8aef95a1374abba0078c2364 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
@@ -16,6 +16,10 @@
 {%-   for pf in struct.packed.packed_fields_in_ordinal_order if pf.field.kind|is_object_kind %}
 {%-     if pf.field.kind|is_union_kind %}
   size += GetSerializedSize_({{input_field_pattern|format(pf.field.name)}}, true);
+{%-     elif pf.field.kind|is_struct_kind %}
+  size += {{input_field_pattern|format(pf.field.name)}}.is_null()
+              ? 0
+              : GetSerializedSize_(*{{input_field_pattern|format(pf.field.name)}});
 {%-     else %}
   size += GetSerializedSize_({{input_field_pattern|format(pf.field.name)}});
 {%-     endif %}
@@ -47,19 +51,21 @@
 {%-     if kind|is_array_kind %}
   const mojo::internal::ArrayValidateParams {{name}}_validate_params(
       {{kind|get_array_validate_params_ctor_args|indent(10)}});
-  mojo::SerializeArray_(mojo::internal::Forward({{input_field}}), {{buffer}},
+  mojo::SerializeArray_(&{{input_field}}, {{buffer}},
       &{{output}}->{{name}}.ptr, &{{name}}_validate_params);
 {%-     elif kind|is_map_kind %}
   const mojo::internal::ArrayValidateParams {{name}}_validate_params(
       {{kind.value_kind|get_map_validate_params_ctor_args|indent(10)}});
   mojo::SerializeMap_(
-      mojo::internal::Forward({{input_field}}), {{buffer}}, &{{output}}->{{name}}.ptr,
+      &{{input_field}}, {{buffer}}, &{{output}}->{{name}}.ptr,
       &{{name}}_validate_params);
 {%-     elif kind|is_union_kind %}
   internal::{{kind.name}}_Data* {{name}}_ptr = &{{output}}->{{name}};
-  SerializeUnion_(mojo::internal::Forward({{input_field}}), {{buffer}}, &{{name}}_ptr, true);
+  SerializeUnion_({{input_field}}.get(), {{buffer}}, &{{name}}_ptr, true);
+{%-     elif kind|is_string_kind %}
+  SerializeString_({{input_field}}, {{buffer}}, &{{output}}->{{name}}.ptr);
 {%-     else %}
-  Serialize_(mojo::internal::Forward({{input_field}}), {{buffer}}, &{{output}}->{{name}}.ptr);
+  Serialize_({{input_field}}.get(), {{buffer}}, &{{output}}->{{name}}.ptr);
 {%-     endif %}
 {%-     if not kind|is_nullable_kind %}
   MOJO_INTERNAL_DLOG_SERIALIZATION_WARNING(
@@ -126,8 +132,15 @@
 {%-     endif %}
 {%-     if kind|is_object_kind %}
 {%-       if kind|is_union_kind %}
-    Deserialize_(&{{input}}->{{name}}, &{{output_field}});
+    {{output_field}} = {{kind|get_name_for_kind}}::New();
+    Deserialize_(&{{input}}->{{name}}, {{output_field}}.get());
+{%-       elif kind|is_struct_kind %}
+    if ({{input}}->{{name}}.ptr) {
+      {{output_field}} = {{kind|get_name_for_kind}}::New();
+      Deserialize_({{input}}->{{name}}.ptr, {{output_field}}.get());
+    }
 {%-       else %}
+{#- Arrays and Maps #}
     Deserialize_({{input}}->{{name}}.ptr, &{{output_field}});
 {%-       endif %}
 {%-     elif kind|is_interface_kind %}