[FFmpeg-trac] #10809(build system:new): libvulkan.so not linked when `--enable-vulkan`.

[FFmpeg]

#10809: libvulkan.so not linked when `--enable-vulkan`.
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             Reporter:  Atemu         |                     Type:  defect
               Status:  new           |                 Priority:  normal
            Component:  build system  |                  Version:  6.1
             Keywords:                |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
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 Summary of the bug:

 When building ffmpeg with `--enable-vulkan` with vulkan-loader and vulkan-
 headers present, the vulkan-loader's libvulkan.so is not linked into the
 ffmpeg executable and ffmpeg is unable to find it at runtime.

 Adding `--enable-libplacebo` aswell as adding libplacebo to the
 dependencies makes the executable linked against the vulkan-loader again.

     $ ldd ./result-bin/bin/ffmpeg | rg vulkan

 vs.

     $ ldd ./result-bin/bin/ffmpeg | rg vulkan
             libvulkan.so.1 => /nix/store/pkrmapls8xvicblivs4mr8qp4xvcm5kh-
 vulkan-loader-1.3.268.0/lib/libvulkan.so.1 (0x00007f37c4efd000)

 Trying to run something like `RADV_PERFTEST=video_decode ./result-
 bin/bin/ffmpeg -init_hw_device "vulkan=vk:0" -hwaccel vulkan
 -hwaccel_output_format vulkan -i ...` results in:

     [AVHWDeviceContext @ 0x1db4280] Unable to open the libvulkan library!
     Device creation failed: -1313558101.
     Failed to set value 'vulkan=vk:0' for option 'init_hw_device': Unknown
 error occurred
     Error parsing global options: Unknown error occurred

 `strace` reveals that it doesn't even attempt to look in vulkan-loader's
 lib dir.

 This bug does _not_ reproduce on ffmpeg 4.4.4, even without libplacebo.
 libvulkan is linked there. It does repro with 5.1.3.

 How to reproduce:
 1. Build with `--enable-vulkan` and vulkan-loader + vulkan-headers in the
 library search path
 2. `ldd` the resulting executable

 Discovered in: https://github.com/NixOS/nixpkgs/pull/281753

 Patches should be submitted to the ffmpeg-devel mailing list and not this
 bug tracker.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10809>
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