Wgpu: Linking Errors.

[ZKing1000]

[ 33%] Linking C executable triangle /usr/bin/ld: CMakeFiles/triangle.dir/main.c.o: in functionmain':
/home/holden/Desktop/work/forks/wgpu/examples/triangle/main.c:260: undefined reference to wgpu_render_pass_set_pipeline' /usr/bin/ld: /home/holden/Desktop/work/forks/wgpu/examples/triangle/main.c:261: undefined reference towgpu_render_pass_set_bind_group'
/usr/bin/ld: /home/holden/Desktop/work/forks/wgpu/examples/triangle/main.c:262: undefined reference to wgpu_render_pass_draw' collect2: error: ld returned 1 exit status make[3]: *** [CMakeFiles/triangle.dir/build.make:101: triangle] Error 1 make[3]: Leaving directory '/run/media/holden/45993E4516E8C2C4/Git/forks/wgpu/examples/triangle/build' make[2]: *** [CMakeFiles/Makefile2:76: CMakeFiles/triangle.dir/all] Error 2 make[2]: Leaving directory '/run/media/holden/45993E4516E8C2C4/Git/forks/wgpu/examples/triangle/build' make[1]: *** [Makefile:84: all] Error 2 make[1]: Leaving directory '/run/media/holden/45993E4516E8C2C4/Git/forks/wgpu/examples/triangle/build' make: *** [Makefile:108: example-triangle] Error 2

[kvark]

Thank you for the report!
I was seeing this as well on Linux, although for the past weeks (months?) there was always more important things to address, so I didn't investigate.
A brief look at the symbols shows that they are there. Also, this works on macOS.
Any help in investigating this would be great!

[kvark]

I double-checked it now, and I was wrong - the symbols are totally missing:

kvark@ant /hub/moz/wgpu/examples/compute/build $ objdump -t /hub/moz/wgpu/target/debug/libwgpu_native.so | grep pass_dispatch
kvark@ant /hub/moz/wgpu/examples/compute/build $ objdump -t /hub/moz/wgpu/target/debug/libwgpu_native.so | grep set_pipeline

[kvark]

And here they are fully exposed by wgpu-core:

    #[no_mangle]
    pub unsafe extern "C" fn wgpu_compute_pass_set_pipeline(
        pass: &mut RawPass,
        pipeline_id: id::ComputePipelineId,
    ) {
        pass.encode(&ComputeCommand::SetPipeline(pipeline_id));
    }

So what might be happening is that the linker doesn't realize that C functions from dependent crates (going from wgpu-native) also need to be exposed?

[ZKing1000]

Here is the Preceding Output:
1.txt

[ZKing1000]

Possibly relevant:
https://github.com/rust-lang/rust/issues/10025
https://github.com/rust-lang/rust/issues/61820

[ZKing1000]

github.com/eqrion/cbindgen/issues/49

[kvark]

@ZKing1000 thanks for the links!

It appears that we are able to work around this issue by adding #[linkage = "external"]

It's annoying and strange that we'd need to put it on each and every function.

Edit: it doesn't work:

error[E0658]: the linkage attribute is experimental and not portable across platforms

[ZKing1000]

I'm not very Familiar with Rust, but I can try to help..

[CryZe]

This is the same issue as this then right? https://github.com/rust-lang/rust/issues/50007

[ZKing1000]

Looks like it.

[ZKing1000]

https://github.com/rust-lang/rust/issues/29603
https://github.com/thomcc/megazord/tree/simple-bug-repro

help: add#![feature(linkage)]to the crate attributes to enable

[ZKing1000]

This looks like the commit that makes it not work: https://github.com/rust-lang/rust/commit/7376ddb291b0cbdfa9d566587f2f27c5670ebf31

[ZKing1000]

I think I fixed... The symbols are present in libwgpu_native.a, but not .so.

examples/triangle/build/CMakeCache.txt:WGPU_LIBRARY:FILEPATH=/home/holden/Desktop/work/forks/wgpu/target/debug/libwgpu_native.a FROM .so

but now there are issues with libm (math library)

[ZKing1000]

Built it:
cd examples/triangle
gcc -lglfw -lm -ldl -pthread -I../../ffi -I../../examples main.c framework.c libwgpu_native.a -o main

backtrace.txt

[ZKing1000]

I compiled this binary on Manjaro Linux with the -g flag.
Use GDB to run and debug.
https://drive.google.com/file/d/10yWzj4Mz4p2wFuu1Aoye3DJ4RtnoN-oE/view?usp=sharing

Edit: Compute Example compiles and runs fine.

[elgunhuseynli]

Same on Windows. I dump exports in .lib file, they are exported but with undersocre prefix.

Dump of file C:\Users\elgun\Desktop\wgpu\target\release\wgpu_native.dll.lib

File Type: LIBRARY

     Exports

       ordinal    name

                  _rust_eh_personality
                  _wgpu_adapter_destroy
                  _wgpu_adapter_request_device
                  _wgpu_bind_group_destroy
                  _wgpu_buffer_destroy
                  _wgpu_buffer_map_read_async
                  _wgpu_buffer_map_write_async
                  _wgpu_buffer_unmap
                  _wgpu_command_buffer_destroy
                  _wgpu_command_encoder_begin_compute_pass
                  _wgpu_command_encoder_begin_render_pass
...

[kvark]

@elgunhuseynli this looks like a different issue. Underscores could very well be expected there - a subject of calling convention. The original problem with linking was about routines exported from wgpu-core only, while your list has stuff from wgpu-native.

[elgunhuseynli]

@kvark If underscores are expected why I'm getting unresolved external symbol error in Visual Studio? Maybe am I doing something wrong? :/

[kvark]

@elgunhuseynli are you seeing the same symbols unresolved as the original issue? If not, let's have a separate one.

[elgunhuseynli]

@kvark I get unresolved external symbol errors for all symbols even for wgpu_request_adapter_async

[kvark]

@elgunhuseynli please file another issue, it looks like nothing links for you at all.

[kvark]

Going to remove that from blockers for the release. First, because Rust users aren't affected. And second, because all is good as long as we provide the binary builds.

[cwfitzgerald]

Seems this issue is external to us. If there is another issue, feel free to re-file.