Issue compiling embedded-svc on rustc 1.75.0-nightly (fee5518cd 2023-11-05)

[Jesse-Cameron]

Hi there,

I recently updated to the most recent version of rust nightly, and was presented with this error when compiling embedded-svc:

   Compiling nb v1.1.0
   Compiling byteorder v1.5.0
   Compiling stable_deref_trait v1.2.0
   Compiling enumset v1.1.3
   Compiling const_format v0.2.32
   Compiling libc v0.2.149
   Compiling atomic-waker v1.1.2
   Compiling void v1.0.2
   Compiling nb v0.1.3
   Compiling embedded-hal v1.0.0-alpha.10
   Compiling anyhow v1.0.75
   Compiling embedded-hal v0.2.7
   Compiling embedded-hal-nb v1.0.0-alpha.2
   Compiling embedded-can v0.4.1
   Compiling hash32 v0.2.1
   Compiling esp-idf-hal v0.41.2
   Compiling serde v1.0.189
   Compiling no-std-net v0.5.0
   Compiling embedded-io v0.4.0
   Compiling esp-idf-sys v0.33.2
   Compiling esp-idf-svc v0.46.2
   Compiling uncased v0.9.9
   Compiling log v0.4.20
   Compiling heapless v0.7.16
   Compiling bytemuck v1.14.0
   Compiling embassy-futures v0.1.0
   Compiling rgb v0.8.36
   Compiling trainer v0.1.0 (/home/jesse/dev/rust/experimental-embed-esp32/trainer)
   Compiling embedded-svc v0.25.3
error[E0277]: `(dyn FnOnce() -> T + Send + 'static)` cannot be sent between threads safely
   --> /home/jesse/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-svc-0.25.3/src/utils/asyncify.rs:72:11
    |
72  |         = BlockingFuture<T> where T: Send;
    |           ^^^^^^^^^^^^^^^^^ `(dyn FnOnce() -> T + Send + 'static)` cannot be sent between threads safely
    |
    = help: the trait `Send` is not implemented for `(dyn FnOnce() -> T + Send + 'static)`
    = note: required for `Unique<(dyn FnOnce() -> T + Send + 'static)>` to implement `Send`
note: required because it appears within the type `Box<dyn FnOnce() -> T + Send>`
   --> /home/jesse/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:195:12
    |
195 | pub struct Box<
    |            ^^^
note: required because it appears within the type `Option<Box<dyn FnOnce() -> T + Send>>`
   --> /home/jesse/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:569:10
    |
569 | pub enum Option<T> {
    |          ^^^^^^
note: required because it appears within the type `BlockingFuture<T>`
   --> /home/jesse/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-svc-0.25.3/src/utils/asyncify.rs:87:16
    |
87  |     pub struct BlockingFuture<T> {
    |                ^^^^^^^^^^^^^^
note: required by a bound in `unblocker::Unblocker::UnblockFuture`
   --> /home/jesse/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-svc-0.25.3/src/executor.rs:95:57
    |
95  |             type UnblockFuture<T>: Future<Output = T> + Send
    |                                                         ^^^^ required by this bound in `Unblocker::UnblockFuture`

For more information about this error, try `rustc --explain E0277`.
error: could not compile `embedded-svc` (lib) due to previous error
warning: build failed, waiting for other jobs to finish...

Reverting to nightly-2023-10-15 resolves my issue, so it's not a deal breaker but wanted to report for your attention.

Let me know if you need any more information from my end!

Reporting

Just reporting this

[ivmarkov]

Fixed yesterday.