Add some missing returns pointed out by -Wreturn-type:
-----------------------------------------------------------------------
[75/1571] Building C object src/xrt/auxiliary/CMakeFiles/aux_util.dir/util/u_config_json.c.o
.../src/xrt/auxiliary/util/u_config_json.c: In function ‘u_gui_state_scene_to_string’:
.../src/xrt/auxiliary/util/u_config_json.c:524:1: warning: control reaches end of non-void function [-Wreturn-type]
524 | }
| ^
-----------------------------------------------------------------------
On some systems fread() is declared with attribute warn_unused_result
and this results in a build warning:
-----------------------------------------------------------------------
Building C object src/xrt/drivers/CMakeFiles/drv_ns.dir/north_star/ns_hmd.c.o
.../src/xrt/drivers/north_star/ns_hmd.c: In function ‘ns_config_load’:
.../src/xrt/drivers/north_star/ns_hmd.c:512:2: warning: ignoring return value of ‘fread’, declared with attribute warn_unused_result [-Wunused-result]
512 | fread(json, 1, file_size, config_file);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-----------------------------------------------------------------------
Explicitly ignore the return value of that fread() to silence the
warning.
And while at it also close config_file in some error paths between
fopen() and fclose() which where leaking the file pointer when jumping
to the parse_error label.
Newer wayland protocols have a new filed in xdg_toplevel_listener which
is not initialized:
-----------------------------------------------------------------------
[215/315] Building C object src/xrt/compositor/CMakeFiles/comp_main.dir/main/comp_window_wayland.c.o
.../src/xrt/compositor/main/comp_window_wayland.c:182:1: warning: missing field 'configure_bounds' initializer [-Wmissing-field-initializers]
};
^
1 warning generated.
-----------------------------------------------------------------------
Detect the version when this is needed and initialize the field to
silence the warning.
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.
