renderdoc_app: Refactor calling convention checks to toolchain vs platform.

[kallisti5]

Description

Adds Haiku platform to renderdoc_app. Currently it missing is breaking the downstream Mesa build.

[kallisti5]

I do question the need to call our every platform here.

#elif defined(__GNUC__)

would catch gcc and clang toolchains if you want to preserve a warning for unknown toolchains.

[baldurk]

Please do not make sweeping changes to the header like this, I want to keep the explicit platform checks. Please only add your platform that you tested to work with RenderDoc.

With that said I'm also surprised that this change is the only thing needed. I've never heard of this platform before, can you share screenshots or video of RenderDoc working on the platform once this change has been made?

[kallisti5]

@baldurk This PR was created at the request of the mesa folks since that header is used upstream in Mesa.

I can refactor to a platform specific check if that's what you prefer.
I'll grab some screenshots of Mesa running on Haiku I guess lol.

[baldurk]

What I'm wondering isn't whether mesa works but whether RenderDoc works. If RenderDoc does not work on your platform then the error is expected and is serving its purpose - to ensure the header isn't included on platforms where it's not going to function.

If RenderDoc doesn't work on your platform then you should make sure to conditionally include it from your program like any other platform-specific header. The header is not intended to be included on any random platform unconditionally and work.

[kallisti5]

So, the program in question is Mesa's gallium zink renderer. (which is the OpenGL -> Vulkan rendering pipeline for Linux, BSD, Darwin, etc)

https://docs.mesa3d.org/systems.html#platforms-and-drivers

Mesa is primarily developed and used on Linux systems. But there’s also support for Windows, other flavors of Unix and other systems such as Haiku. We’re actively developing and maintaining several hardware and software drivers.

You're going to run into the same kind of request for all the other non-Linux UNIX platforms as well at some point.

You're correct that renderdoc itself doesn't function on Haiku since Haiku doesn't use X11.

I guess the best path would be to make Mesa optionally exclude renderdoc and not build it into the rendering pipeline by default. (which is kind of a bummer, I know it's useful to a lot of folks)

[baldurk]

Whether other platforms will have the same request is irrelevant as I will have the same question about whether RenderDoc actually works. Of course mesa is free to support whatever platforms it likes and I'm not going to dictate that, but it is not a goal for this project to support arbitrary obscure platforms either for compilation or runtime support.

If your platform does not work with RenderDoc then mesa should indeed conditionally include the header, as I'm sure it does for other non-generic headers. It will still work correctly on all relevant platforms where RenderDoc is supported. I'll close this PR as it sounds like your platform will not work with RenderDoc and I do not want to have non-functional code compiling.