[FFmpeg-devel] [PATCH] hwcontext_vulkan: make 2 public functions always available

[Hendrik Leppkes]

On Thu, Dec 2, 2021 at 7:13 PM Andreas Rheinhardt
<andreas.rheinhardt at outlook.com> wrote:
>
> Lynne:
> > The issue is that if ffmpeg is compiled without Vulkan, and an API
> > user includes and uses the functions exposed in hwcontext_vulkan.h,
> > then a linking error will happen, as the hwcontext_vulkan.c file has
> > not been compiled.
> >
> > Move the functions to another file, and make it always compiled. The
> > functions do not use any Vulkan functions.
> >
> > Patch attached.
> >
> >
>
> 1. Isn't a linking error exactly what is intended in such cases?

Just do document what was already said on IRC:

I believe a stable ABI is important, and that includes always
exporting the same symbols on any given platform, no matter the build
configuration.
That way you can use binary distributions of our libraries without
needing to worry it was build just right, and use such optional
features when they are functional.

It was suggested to me that I should just dlsym any "optional"
features, but thats really forcing a lot of complexity on any user-app
just to save a few bytes of stub functions to ensure linking or
dynamic loading works.

I believe we have in the past included stubs for APIs that might not
be functional at all times, and we should continue to do so and patch
any holes that might have crept up here.

- Hendrik