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FAQ and common errors

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Timo Lang edited this page Mar 13, 2025 · 8 revisions

Most common errors:

error[E0432]: unresolved import embassy_executor::Executor

21 | pub use embassy_executor::Executor; // Please activate the `executor-thread` or `executor-interrupt` feature on the embassy-executor crate (v0.7.x)!
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ no `Executor` in the root

Please make sure, that:

  1. You have activated at least one of the features executor-thread or executor-interrupt on the embassy-executor crate. e.g. by adding embassy-executor = { default-features = false, version = "0.7.0", features = ["executor-thread", "arch-cortex-m"] } to your crate dependencies.
  2. You only use one single version of embassy-executor throughout your crate graph, check with cargo tree | grep "embassy-executor " -B3.
    If you want to use a git version of embassy, please patch embassy in the [patch.crates-io] section, instead of adding embassy-executor = { git="..."} only on your crate.

error[E0463]: can't find crate for test

This can happen if you forget to add harness = false to your Cargo.toml for each test.

Furthermore, this error can happen if you invoke cargo test without any additional arguments. Apparently cargo test wants to also test the binaries...

Adding the following to Cargo.toml helps as a workaround.

[[bin]]
name = "embedded-example-test"
path = "src/main.rs"
+ test = false


[lib]
+ test = false

Alternatively, you can also run cargo test --tests to only run the integration tests.

rust-lld: error: undefined symbol: embedded_test_linker_file_not_added_to_rustflags

Make sure you've added the following line to your build.rs linker script:

println!("cargo::rustc-link-arg-tests=-Tembedded-test.x");

You can also add rustflags = [ "-C", "link-arg=-Tembedded-test.x" ] to your .cargo/config.toml file. But then you need to move embedded-test from [dev-dependencies] to [dependencies] in your Cargo.toml.

rust-lld: error: duplicate symbol: _SEGGER_RTT

You probably have the init-log feature activated on embedded-test while at the same time using a crate like defmt-rtt or rtt-log. You need to either setup the logger yourselve (with a crate of your choice) or let embedded-test do it (init-log feature)

probe-rs exits directly after flashing (semihosting...)

Make sure you're using at least probe-rs 0.24.0. Older versions do not support embedded-test yet.

probe-rs complains about unexpected arguments

Make sure you're using at least probe-rs 0.24.0. Older versions do not support embedded-test yet.
Otherwise, please open an issue including the commandline that was used to invoke probe-rs.

probe-rs fails to link when using embedded-test with defmt 

  = note: rust-lld: error: undefined symbol: _defmt_release
          >>> referenced by mod.rs:71
          ...

If only your test builds fail but your main application builds fine, you probably have some linker scripts that are not linked for the tests but are linked for the main application.

Check your build.rs for println!("cargo:rustc-link-arg-bins=-Tdefmt.x"); or some other dependency which might be missing. Add println!("cargo:rustc-link-arg-tests=-Tdefmt.x"); or some other dependency which might be missing. to your build.rs.

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