Some variables are only used in asserts, so they may be unused
depending on the build type:
-----------------------------------------------------------------------
[68/315] Building C object src/xrt/auxiliary/CMakeFiles/aux_util.dir/util/u_sink_combiner.c.o
.../src/xrt/auxiliary/util/u_sink_combiner.c:188:11: warning: unused variable 'diff_ns' [-Wunused-variable]
int64_t diff_ns = frames[0]->timestamp - frames[1]->timestamp;
^
1 warning generated.
[205/315] Building C object src/xrt/compositor/CMakeFiles/comp_main.dir/main/comp_renderer.c.o
.../src/xrt/compositor/main/comp_renderer.c:872:17: warning: unused variable 'layer_count' [-Wunused-variable]
const uint32_t layer_count = c->base.slot.layer_count;
^
1 warning generated.
-----------------------------------------------------------------------
Mark them as XRT_MAYBE_UNUSED to fix the build warnings.
Add some missing returns pointed out by -Wreturn-type:
-----------------------------------------------------------------------
[32/315] Building C object src/xrt/auxiliary/CMakeFiles/aux_gstreamer.dir/gstreamer/gst_sink.c.o
.../src/xrt/auxiliary/gstreamer/gst_sink.c:53:1: warning: non-void function does not return a value in all control paths [-Wreturn-type]
}
^
1 warning generated.
[84/315] Building C object src/xrt/auxiliary/CMakeFiles/aux_vk.dir/vk/vk_compositor_flags.c.o
.../src/xrt/auxiliary/vk/vk_compositor_flags.c:117:1: warning: non-void function does not return a value in all control paths [-Wreturn-type]
}
^
.../src/xrt/auxiliary/vk/vk_compositor_flags.c:146:1: warning: non-void function does not return a value in all control paths [-Wreturn-type]
}
^
2 warnings generated.
-----------------------------------------------------------------------
For the function returning VkImageAspectFlags return a literal 0 because
the enum values VK_IMAGE_ASPECT_NONE or VK_IMAGE_ASPECT_NONE_KHR may not
always be defined.
The size field in comp_buffer was never assigned, and also never used as
all comp_buffer users rely on the allocation_size field.
Use the size field to store the size originally requested when creating
the buffer which could be different from the value returned in the
allocation_size field.
Having both sizes available allows a user to check if allocation_size is
in fact different from the requested size.
