flutter_elinux.h not C importable

[lhoward]

flutter_elinux.h appears to be C-compatible by virtue of its extern "C" guard but it includes some definitions with reference parameters:

FLUTTER_EXPORT FlutterDesktopViewControllerRef
FlutterDesktopViewControllerCreate(
    const FlutterDesktopViewProperties& view_properties,
    FlutterDesktopEngineRef engine);

FLUTTER_EXPORT FlutterDesktopEngineRef FlutterDesktopEngineCreate(
    const FlutterDesktopEngineProperties& engine_properties);

This causes problems with languages such as Swift that do not support C++ interoperability (at least, in shipping versions).

Upstream raised and fixed this in flutter/flutter#75465.

[lhoward]

Also would be nice to import FlutterDesktopMessengerAddRef and FlutterDesktopMessengerRelease if possible.

[lhoward]

Should be fixed in https://github.com/PADL/flutter-embedded-linux/tree/lhoward/345 (didn't create a PR, per README).

[HidenoriMatsubayashi]

Thank you. Can you please create a PR with Developer’s Certificate of Origin (DCO) in your commit message? Also, please update (AUTHORS)[https://github.com/sony/flutter-embedded-linux/blob/master/AUTHORS] too.

[HidenoriMatsubayashi]

Also would be nice to import FlutterDesktopMessengerAddRef and FlutterDesktopMessengerRelease if possible.

Remaining task.

[lhoward]

I will do, I need to figure out how to build it before trying anything more substantial.

[HidenoriMatsubayashi]

Okay, thank you.

[HidenoriMatsubayashi]

Closing. Thank you so much, Ihoward!

[lhoward]

Thank you for merging so quickly. I've tested the latest main with my Swift wrapper and it is working :)