Wgpu: Fix Error Message When No Windowing Backend Found

[buxx]

Hello,

Got this error when running example:

➜  wgpu-rs git:(master) RUST_BACKTRACE=1 cargo run --example cube
    Finished dev [unoptimized + debuginfo] target(s) in 0.10s
     Running `target/debug/examples/cube`
[2020-05-25T08:18:10Z ERROR gfx_backend_vulkan] [loader] setupLoaderTermPhysDevs:  Failed to detect any valid GPUs in the current config
[2020-05-25T08:18:10Z ERROR gfx_backend_vulkan] [loader] vkEnumeratePhysicalDevices: Failed in dispatch call used to determine number of available GPUs
[2020-05-25T08:18:10Z ERROR gfx_backend_vulkan] [loader] setupLoaderTermPhysDevs:  Failed to detect any valid GPUs in the current config
[2020-05-25T08:18:10Z ERROR gfx_backend_vulkan] [loader] setupLoaderTrampPhysDevs:  Failed during dispatch call of 'vkEnumeratePhysicalDevices' to lower layers or loader.
[2020-05-25T08:18:10Z ERROR gfx_backend_vulkan] Could not enumerate physical devices! Initialization of a object has failed
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', examples/cube/../framework.rs:62:19
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1063
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1426
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:204
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:224
  10: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:470
  11: rust_begin_unwind
             at src/libstd/panicking.rs:378
  12: core::panicking::panic_fmt
             at src/libcore/panicking.rs:85
  13: core::panicking::panic
             at src/libcore/panicking.rs:52
  14: core::option::Option<T>::unwrap
             at /rustc/4fb7144ed159f94491249e86d5bbd033b5d60550/src/libcore/macros/mod.rs:10
  15: cube::framework::run_async::{{closure}}
             at examples/cube/../framework.rs:62
  16: <std::future::GenFuture<T> as core::future::future::Future>::poll
             at /rustc/4fb7144ed159f94491249e86d5bbd033b5d60550/src/libstd/future.rs:44
  17: futures_executor::local_pool::block_on::{{closure}}
             at /home/bastien/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-executor-0.3.5/src/local_pool.rs:317
  18: futures_executor::local_pool::run_executor::{{closure}}
             at /home/bastien/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-executor-0.3.5/src/local_pool.rs:87
  19: std::thread::local::LocalKey<T>::try_with
             at /rustc/4fb7144ed159f94491249e86d5bbd033b5d60550/src/libstd/thread/local.rs:262
  20: std::thread::local::LocalKey<T>::with
             at /rustc/4fb7144ed159f94491249e86d5bbd033b5d60550/src/libstd/thread/local.rs:239
  21: futures_executor::local_pool::run_executor
             at /home/bastien/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-executor-0.3.5/src/local_pool.rs:83
  22: futures_executor::local_pool::block_on
             at /home/bastien/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-executor-0.3.5/src/local_pool.rs:317
  23: cube::framework::run
             at examples/cube/../framework.rs:198
  24: cube::main
             at examples/cube/main.rs:361
  25: std::rt::lang_start::{{closure}}
             at /rustc/4fb7144ed159f94491249e86d5bbd033b5d60550/src/libstd/rt.rs:67
  26: std::rt::lang_start_internal::{{closure}}
             at src/libstd/rt.rs:52
  27: std::panicking::try::do_call
             at src/libstd/panicking.rs:303
  28: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:86
  29: std::panicking::try
             at src/libstd/panicking.rs:281
  30: std::panic::catch_unwind
             at src/libstd/panic.rs:394
  31: std::rt::lang_start_internal
             at src/libstd/rt.rs:51
  32: std::rt::lang_start
             at /rustc/4fb7144ed159f94491249e86d5bbd033b5d60550/src/libstd/rt.rs:67
  33: main
  34: __libc_start_main
  35: _start
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

• Linux PC-Fixe-01 4.9.0-12-amd64 gfx-rs/wgpu-rs#1 SMP Debian 4.9.210-1 (2020-01-20) x86_64 GNU/Linux
• Cedar [Radeon HD 5000/6000/7350/8350 Series]

➜  iced git:(master) ✗ sudo find /dev -group video
/dev/fb0
/dev/dri/card0
/dev/dri/renderD128
/dev/dri/controlD64
➜  iced git:(master) ✗ glxinfo | grep -i vendor
server glx vendor string: SGI
client glx vendor string: Mesa Project and SGI
    Vendor: X.Org (0x1002)
OpenGL vendor string: X.Org

Anything can i do ?

[kvark]

It doesn't look like your platform supports any APIs that we can use. I.e. "Failed to detect any valid GPUs in the current config" comes from the Vulkan loader, which is a part of the Vulkan SDK in your system. Therefore, you are essentially blocked on https://github.com/gfx-rs/wgpu/issues/450

[charles-r-earp]

Did you install vulkan-utils (ie via sudo apt install vulkan-utils)? I found this was necessary, and isn't AFAIK documented anywhere.

[antonok-edm]

Not quite the same, but I've gotten a similar error after upgrading to wgpu 0.6. I've been using this to enable xcb support (from https://github.com/gfx-rs/wgpu/pull/351):

[target.'cfg(all(unix, not(target_os = "ios"), not(target_os = "macos")))'.dependencies]
gfx-backend-vulkan = { version = "^ 0.5", features = ["xcb"] }

Of course, having forgotten to update that in tandem, I had two versions of gfx-hal simultaneously, with the important one missing xcb support.

That left me with the following, rather uninformative panic:

thread '<unnamed>' panicked at 'called `Option::unwrap()` on a `None` value', /home/antonok/.config/cargo/registry/src/github.com-1ecc6299db9ec823/wgpu-core-0.6.0/src/hub.rs:746:33

In hindsight, version = "*" is a much better idea here. But the error message could definitely be improved if support for the required windowing backend is missing.

[kvark]

Agreed, let's improve the error message there.