Cannot compile hello-compute on Windows

[jpryne]

   Compiling wgpu v0.4.0 (C:\Users\jack_\code\WASM\wgpu-rs)
error[E0658]: async fn is unstable
  --> examples\hello-compute\main.rs:4:1
   |
4  | / async fn run() {
5  | |     env_logger::init();
6  | |
7  | |     // For now this just panics if you didn't pass numbers. Could add proper error handling.
...  |
16 | |     println!("Times: {:?}", execute_gpu(numbers).await);
17 | | }
   | |_^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/50547

error[E0658]: async/await is unstable
  --> examples\hello-compute\main.rs:16:29
   |
16 |     println!("Times: {:?}", execute_gpu(numbers).await);
   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/50547

error[E0658]: async fn is unstable
   --> examples\hello-compute\main.rs:19:1
    |
19  | / async fn execute_gpu(numbers: Vec<u32>) -> Vec<u32> {
20  | |     let slice_size = numbers.len() * std::mem::size_of::<u32>();
21  | |     let size = slice_size as wgpu::BufferAddress;
22  | |
...   |
107 | |     }
108 | | }
    | |_^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/50547

error[E0658]: async/await is unstable
  --> examples\hello-compute\main.rs:99:26
   |
99 |     if let Ok(mapping) = staging_buffer.map_read(0u64, size).await {
   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/50547

error: aborting due to 4 previous errors

For more information about this error, try `rustc --explain E0658`.
error: Could not compile `wgpu`.

[grovesNL]

Hi @jpryne, which version of stable Rust are you using? async/await was stabilized in 1.39 (see https://areweasyncyet.rs/). If you have rustup, could you try updating your stable Rust version with rustup update?

[jpryne]

Thank you, grovesNL, for your suggestion. I felt rather foolish, and certain this would solve the issue. Alas, I am still having this problem:
stable-x86_64-pc-windows-msvc updated - rustc 1.41.1 (f3e1a954d 2020-02-24)
nightly-x86_64-pc-windows-msvc updated - rustc 1.43.0-nightly (2890b37b8 2020-03-06)

PS C:\code\WASM\wgpu-rs\examples> cargo run --example hello-compute 1 2 3 4

Compiling wgpu v0.4.0 (C:\code\WASM\wgpu-rs)

error[E0658]: async fn is unstable

[kvark]

Clearly your build is using a different rustc than what was installed?

[grovesNL]

@jpryne maybe you could try rustup default stable in case your default is set to a specific version

[jpryne]

@grovesNL Made sure to set my default rustup to stable, yet am still getting this error.

[grovesNL]

What happens if you specify the stable toolchain explicitly with cargo +stable run --example hello-compute 1 2 3 4?

[GabrielMajeri]

I've managed to run cargo build --examples successfully on Windows 10 using Rust stable, did not reproduce the issue.

rustc version: rustc 1.42.0 (b8cedc004 2020-03-09)

[jpryne]

@grovesNL :

What happens if you specify the stable toolchain explicitly with cargo +stable run --example hello-compute 1 2 3 4?

error: no such subcommand: '+stable'

@GabrielMajeri
I'm sure I'm doing something wrong, but I'm slammed right now. Feel free to close.

[grovesNL]

@jpryne maybe there is something wrong with your Rust installation and the wrong cargo binary is being used somehow? For example, somebody had a similar problem in rust-lang/rustup#762 (comment)