Hi, recently I was looking into dynamically loading libwayland to be able to support both X11 and Wayland, without requiring libwayland. For our project is currently a requirement for adopting Wayland.
While I did manage to get this working, use of variadic arguments adds quite some complexity that could be avoided. >From what I can tell there is no portable way to wrap `wl_proxy_marshal_flags` see [0], Using GCC's `__builtin_apply` does work but this isn't available in CLANG so I'd prefer to avoid it. The only portable way I found to handle this was to create a header that needs to be included before any of the headers generated by wayland-scanner (which make calls to `wl_proxy_marshal_flags`), which can be replaced by a reference to a function pointer instead of requiring the function to exist and link at build time. This is quite messy and means it's not practical to create an isolated dynamic loader for libwayland-client. There are a few possible solutions to this but they involve additions to wayland API. - Make wl_argument_from_va_list public, so wrapper functions can always construct `wl_argument` from `va_list` and forward that to the `wl_argument` version of functions. - Have va_list versions of all functions (similar to printf/vprintf). - The ability to retrieve the number of arguments a function expects would also allow wrappers to forward `va_args`, although it's fairly obscure. - Support for wayland-scanner generating code that doesn't call variadic functions. This is more of a workaround, but would at least mean that projects could call into alternative versions of the functions. As far as I can see, exposing `wl_argument_from_va_list` is the most straightforward solution. Would the Wayland project consider tweaks to the API that make dynamically loading libwayland libraries possible? [0]: https://stackoverflow.com/questions/72781222 -- - Campbell
