Errors compiling for ESP32 std

[misterzirillo]

Hello!

I've recently taken a dive into the embedded rust world and have run across a problem. I have cloned this repo https://github.com/ivmarkov/rust-esp32-std-demo and gotten it running on my ESP32-C3-M1 using nightly. However, when I add this dependency I get a compilation error.

 RUST_BACKTRACE=1 cargo build
   Compiling riscv v0.7.0
error: failed to run custom build command for `riscv v0.7.0`

Caused by:
  process didn't exit successfully: `./target/debug/build/riscv-6960dc4cd1ce77dc/build-script-build` (exit status: 101)
  --- stderr
  thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', ~/.cargo/registry/src/github.com-1ecc6299db9ec823/riscv-0.7.0/build.rs:22:10
  stack backtrace:
     0: rust_begin_unwind
               at /rustc/cb121987158d69bb894ba1bcc21dc45d1e0a488f/library/std/src/panicking.rs:584:5
     1: core::panicking::panic_fmt
               at /rustc/cb121987158d69bb894ba1bcc21dc45d1e0a488f/library/core/src/panicking.rs:142:14
     2: core::result::unwrap_failed
               at /rustc/cb121987158d69bb894ba1bcc21dc45d1e0a488f/library/core/src/result.rs:1785:5
     3: core::result::Result<T,E>::unwrap
               at /rustc/cb121987158d69bb894ba1bcc21dc45d1e0a488f/library/core/src/result.rs:1078:23
     4: build_script_build::main
               at ./build.rs:18:9
     5: core::ops::function::FnOnce::call_once
               at /rustc/cb121987158d69bb894ba1bcc21dc45d1e0a488f/library/core/src/ops/function.rs:248:5
  note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

I realize this library doesn't support riscv yet, however I thought since std is available that it would work anyway.

[dependencies]
shared-bus = { version = '0.2.3', features = ['std'], default-features = false }

Is this possible with a config change? My rust knowledge is very limited at this point.

[Rahix]

Hm, the error is unclear to me. It stems from this line in the riscv build-script:

https://github.com/rust-embedded/riscv/blob/498924d063b25f46c69d2888743a2f720528c927/build.rs#L22

This does not seem to be related to shared-bus at first glance?

Btw, you do not need any special support for single-threaded bus-sharing. This means can use shared-bus just fine without activating any special features as long as you do not need to access the bus from multiple threads/tasks/execution contexts.

[misterzirillo]

I can't see how it relates either. When I add shared-bus to my dependencies I get the error, even when no features are enabled. When removed the build succeeds. Something about this crate doesn't agree with that script or vice-versa.

Perhaps this issue belongs in the rust-embedded repo instead? Feel free to close and I'll bring it over there.

[Rahix]

Yeah, I'd ask over in rust-embedded/riscv, maybe someone over there has an idea... Are you sure it works without shared-bus? I'm really confused how the addition of a crate would make a file in another crate vanish. Maybe try adding the dependencies of shared-bus instead, to see if any of them are to blame? I.e.

embedded-hal = "0.2.3"
nb = "0.1.3"
atomic-polyfill = "0.1.6"

[misterzirillo]

It seems the problem is with atomic-polyfill. Adding it rather than shared-bus results in the same error. Bumping to newer versions doesn't solve it.

[Rahix]

Okay, that makes a bit more sense I guess... So maybe try asking over there if they have any idea. In the meantime: We plan to make atomic-polyfill optional in shared-bus anyway (#31) which would then mean you can at least use the crate in some way.

[Rahix]

I pushed commit e8731935fdbf ("For now, only pull in atomic-polyfill for cortex-m feature") which should help in your case. I will publish a new release shortly.

[misterzirillo]

Thanks for the update. I'm confident that should do it, at least it did in my fork.