The Crate Does not Compile when the defmt-03 Feature is Enabled

[joboudreault]

Problem

Currently (on master commit 1c585d4), the crate embedded-hal and embedded-io does not compile when enabling the defmt-03 feature. The following command is run :

[./embedded-hal] $ cargo build --features defmt-03;

And these errors are returned :

Errors

error[E0433]: failed to resolve: could not find `defmt` in the list of imported crates
   --> embedded-hal/src/i2c.rs:192:41
    |
192 | #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]
    |                                         ^^^^^^^^^^^^^ could not find `defmt` in the list of imported crates
    |
    = note: this error originates in the derive macro `defmt::Format` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider importing this crate through its public re-export
    |
164 + use crate::defmt;
    |

error[E0433]: failed to resolve: could not find `defmt` in the list of imported crates
   --> embedded-hal/src/i2c.rs:192:41
    |
192 | #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]
    |                                         ^^^^^^^^^^^^^ could not find `defmt` in the list of imported crates
    |
    = note: this error originates in the derive macro `defmt::Format` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0433]: failed to resolve: could not find `defmt` in the list of imported crates
   --> embedded-hal/src/i2c.rs:304:41
    |
304 | #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]
    |                                         ^^^^^^^^^^^^^ could not find `defmt` in the list of imported crates
    |
    = note: this error originates in the derive macro `defmt::Format` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider importing this crate through its public re-export
    |
164 + use crate::defmt;
    |

error[E0433]: failed to resolve: could not find `defmt` in the list of imported crates
   --> embedded-hal/src/i2c.rs:304:41
    |
304 | #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]
    |                                         ^^^^^^^^^^^^^ could not find `defmt` in the list of imported crates
    |
    = note: this error originates in the derive macro `defmt::Format` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0433]: failed to resolve: could not find `defmt` in the list of imported crates
   --> embedded-hal/src/spi.rs:201:41
    |
201 | #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]
    |                                         ^^^^^^^^^^^^^ could not find `defmt` in the list of imported crates
    |
    = note: this error originates in the derive macro `defmt::Format` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider importing this crate through its public re-export
    |
174 + use crate::defmt;
    |

error[E0433]: failed to resolve: could not find `defmt` in the list of imported crates
   --> embedded-hal/src/spi.rs:201:41
    |
201 | #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]
    |                                         ^^^^^^^^^^^^^ could not find `defmt` in the list of imported crates
    |
    = note: this error originates in the derive macro `defmt::Format` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0433]: failed to resolve: could not find `defmt` in the list of imported crates
   --> embedded-hal/src/spi.rs:319:41
    |
319 | #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]
    |                                         ^^^^^^^^^^^^^ could not find `defmt` in the list of imported crates
    |
    = note: this error originates in the derive macro `defmt::Format` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider importing this crate through its public re-export
    |
174 + use crate::defmt;
    |

error[E0433]: failed to resolve: could not find `defmt` in the list of imported crates
   --> embedded-hal/src/spi.rs:319:41
    |
319 | #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]
    |                                         ^^^^^^^^^^^^^ could not find `defmt` in the list of imported crates
    |
    = note: this error originates in the derive macro `defmt::Format` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0433`.
error: could not compile `embedded-hal` (lib) due to 8 previous errors

This is run by the following Rust version :

cargo 1.79.0 (ffa9cf99a 2024-06-03)
release: 1.79.0
commit-hash: ffa9cf99a594e59032757403d4c780b46dc2c43a
commit-date: 2024-06-03
host: x86_64-unknown-linux-gnu
libgit2: 1.7.2 (sys:0.18.3 vendored)
libcurl: 8.6.0-DEV (sys:0.4.72+curl-8.6.0 vendored ssl:OpenSSL/1.1.1w)
ssl: OpenSSL 1.1.1w  11 Sep 2023
os: Arch Linux [64-bit]

Solution

I forked the repository and pushed a branch that successfully compiles embedded-hal and embedded-io in a standalone fashion. It is confirmed to work for our needs.

However, I know this could conflict with a previous discussion on PR #481.

What is happening in this case ?

Thanks for your help.

[Dirbaio]

I cannot reproduce this

git[dirbaio@mercury ~]$ git clone https://github.com/rust-embedded/embedded-hal
Cloning into 'embedded-hal'...
remote: Enumerating objects: 4476, done.
remote: Counting objects: 100% (946/946), done.
remote: Compressing objects: 100% (221/221), done.
remote: Total 4476 (delta 781), reused 781 (delta 725), pack-reused 3530
Receiving objects: 100% (4476/4476), 1.49 MiB | 6.91 MiB/s, done.
Resolving deltas: 100% (2898/2898), done.
[dirbaio@mercury ~]$ cd embedded-hal
[dirbaio@mercury embedded-hal]$ cargo build --features defmt-03
(...)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 10.05s
[dirbaio@mercury embedded-hal]$ cd embedded-hal
[dirbaio@mercury embedded-hal]$ cargo build --features defmt-03
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.02s
[dirbaio@mercury embedded-hal]$ 
[dirbaio@mercury embedded-hal]$ cargo --version -v
cargo 1.79.0 (ffa9cf99a 2024-06-03)
release: 1.79.0
commit-hash: ffa9cf99a594e59032757403d4c780b46dc2c43a
commit-date: 2024-06-03
host: x86_64-unknown-linux-gnu
libgit2: 1.7.2 (sys:0.18.3 vendored)
libcurl: 8.6.0-DEV (sys:0.4.72+curl-8.6.0 vendored ssl:OpenSSL/1.1.1w)
ssl: OpenSSL 1.1.1w  11 Sep 2023
os: Arch Linux [64-bit]
[dirbaio@mercury embedded-hal]$ rustc --version -v
rustc 1.79.0 (129f3b996 2024-06-10)
binary: rustc
commit-hash: 129f3b9964af4d4a709d1383930ade12dfe7c081
commit-date: 2024-06-10
host: x86_64-unknown-linux-gnu
release: 1.79.0
LLVM version: 18.1.7

Perhaps you have an old Cargo.lock file somewhere, perhaps there's something wrong with your Rust installation so it's actually using an older rustc or something.

[joboudreault]

Indeed, after whipping and reinstalling the Rustup installation and Cargo.lock and target/, the embedded-hal and embedded-io packages now compiles with the defmt-03 feature.

However, I used the x86_64-unknown-linux-gnu because the problem also happened with it ; what we are actually compiling for is an ESP32-S3 Xtensa platform. I created a MRE in this repository (here) to showcase the same problem while compiling for the device.

In the root Cargo.toml, it successfully compiles only if I do not comment out the patch.crates-io section.

  --> /home/ferris/.cargo/registry/src/index.crates.io-6f17d22bba15001f/embedded-hal-1.0.0/src/lib.rs:21:5
   |
21 | use defmt as defmt;
   |     ^^^^^^^^^^^^^^ no external crate `defmt`

For more information about this error, try `rustc --explain E0432`.
error: could not compile `embedded-hal` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...

Xtensa Rust version:

$ rustup run esp cargo -Vv
cargo 1.77.0-nightly (3fe68eabf 2024-02-29)
release: 1.77.0-nightly
commit-hash: 3fe68eabf93cbf3772bbcad09a9206c783e2de3f
commit-date: 2024-02-29
host: x86_64-unknown-linux-gnu
libgit2: 1.7.2 (sys:0.18.2 vendored)
libcurl: 8.5.0-DEV (sys:0.4.70+curl-8.5.0 vendored ssl:OpenSSL/1.1.1w)
ssl: OpenSSL 1.1.1w  11 Sep 2023
os: Arch Linux [64-bit]

$ rustup run esp rustc -Vv
rustc 1.77.0-nightly (424037dcb 2024-03-18) (1.77.0.0)
binary: rustc
commit-hash: 424037dcb6937656992747c4bbff310c40061498
commit-date: 2024-03-18
host: x86_64-unknown-linux-gnu
release: 1.77.0-nightly
LLVM version: 17.0.1

Could you try if the error happens on your side ? The required compiler and installation steps are documented in the README.md.

[Dirbaio]

Same, it build fine for me. Both with and without the [patch.crates-io].

[joboudreault]

Ok, then I will create a clean Docker container and try reproducing it there. Thanks for your time.