* 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

 {#  TODO(yzshen): Make these templates more readable. #}
 
 {#  Computes the serialized size for the specified struct.
     |struct| is the struct definition.
     |input_field_pattern| should be a pattern that contains one string
     placeholder, for example, "input->%s", "p_%s". The placeholder will be
     substituted with struct field names to refer to the input fields.
     This macro is expanded to compute seriailized size for both:
     - user-defined structs: the input is an instance of the corresponding struct
       wrapper class.
     - method parameters/response parameters: the input is a list of
       arguments.
     It declares |size| of type size_t to store the resulting size. #}
 {%- macro get_serialized_size(struct, input_field_pattern) -%}
   size_t size = sizeof(internal::{{struct.name}}_Data);
 {%-   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 %}
 {%-   endfor %}
 {%- endmacro -%}
 
 {#  Serializes the specified struct.
     |struct| is the struct definition.
     |struct_display_name| is the display name for the struct that can be showed
     in error/log messages, for example, "FooStruct", "FooMethod request".
@@ skipping 11 matching lines @@
   internal::{{struct.name}}_Data* {{output}} =
       internal::{{struct.name}}_Data::New({{buffer}});
 {%- for pf in struct.packed.packed_fields_in_ordinal_order %}
 {%-   set input_field = input_field_pattern|format(pf.field.name) %}
 {%-   set name = pf.field.name %}
 {%-   set kind = pf.field.kind %}
 {%-   if kind|is_object_kind %}
 {%-     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(
 {%-       if kind|is_union_kind %}
       {{output}}->{{name}}.is_null(),
 {%-       else %}
       !{{output}}->{{name}}.ptr,
 {%-       endif %}
       mojo::internal::VALIDATION_ERROR_UNEXPECTED_NULL_POINTER,
       "null {{name}} in {{struct_display_name}}");
@@ skipping 46 matching lines @@
 {%-     set output_field = output_field_pattern|format(pf.field.name) %}
 {%-     set name = pf.field.name %}
 {%-     set kind = pf.field.kind %}
 {%-     if pf.min_version > last_checked_version %}
 {%-       set last_checked_version = pf.min_version %}
     if ({{input}}->header_.version < {{pf.min_version}})
       break;
 {%-     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 %}
     mojo::internal::InterfaceDataToPointer(&{{input}}->{{name}}, &{{output_field}});
 {%-     elif kind|is_interface_request_kind %}
     {{output_field}}.Bind(mojo::MakeScopedHandle(mojo::internal::FetchAndReset(&{{input}}->{{name}})));
 {%-     elif kind|is_any_handle_kind %}
     {{output_field}}.reset(mojo::internal::FetchAndReset(&{{input}}->{{name}}));
 {%-     elif kind|is_enum_kind %}
     {{output_field}} = static_cast<{{kind|cpp_wrapper_type}}>({{input}}->{{name}});
 {%-     else %}
     {{output_field}} = {{input}}->{{name}};
 {%-     endif %}
 {%-   endfor %}
   } while (false);
 {%- endmacro %}