Invalid generated code for allocation_size for empty record

[artemyarulin]

For the UDL

namespace A {};
dictionary B {};

If I run a latest released generator (v0.6.2+v0.25.0) uniffi-bindgen-cpp foo.udl --out-dir build it will create a A.cpp with this code at end end

void FfiConverterTypeB::write(RustStream &stream, const B &val) {
}

int32_t FfiConverterTypeB::allocation_size(const B &val) {
    return 
}

}} // namespace A

Notice missing value after return for allocation_size.

I'm not sure how generator works, but my guess it's because template iterates through all the fields and if there are none then there is no fallback value:

uniffi-bindgen-cpp/bindgen/src/bindings/cpp/templates/rec.cpp

Lines 35 to 39 in 1521029

	int32_t {{ ffi_converter_name }}::allocation_size(const {{ class_name }} &val) {
	return {% for field in rec.fields() %}
	{{ field|allocation_size_fn}}(val.{{ field.name()|var_name() }}){% if !loop.last %} +{% else -%};{%- endif %}
	{%- endfor %}
	}

[Lipt0nas]

Hey! sorry for the late reply, could you give the branch a try to see if it works as expected?

[artemyarulin]

Yeah, that solves it - thanks a lot!

[Lipt0nas]

Nice! I'll make a new tag with the changes then