If you don't read/write FIDL, or interact with generated FIDL bindings, you may stop reading now.
Named method payloads are now supported in FIDL:
This style is encouraged for new method definitions where appropriate, but already existing definitions will not be proactively converted to support this new syntax.
Named payload conversions are 100% API preserving for struct payloads, which as of this writing are the only payloads in fuchsia.git, though support for table and union payloads is just around the corner. The OldProtocol/NewProtocol example above will result in the following, functionally identical HLCPP output:
And this (also identical) Rust output: