build for xtensa architecture (esp32, embedded) fails with confusing error

[crabdancing]

I'm working on a somewhat nontrivial project with multiple built targets, each of which have multiple architectures. Here is the build failure I'm getting.

Key point:

Caused by:
  process didn't exit successfully: `rustc - --crate-name ___ --print=file-names -C link-arg=-nostartfiles --target xtensa-esp32-none-elf --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro --print=sysroot --print=split-debuginfo --print=crate-name --print=cfg` (exit status: 1)
  --- stderr
  error: Error loading target specification: Could not find specification for target "xtensa-esp32-none-elf". Run `rustc --print target-list` for a list of built-in targets

If I run rustc --print target-list, I confirm that xtensa-esp32-none-elf is in the build environment -- which is also the toolchain package that crane is using. So I'm not sure why it's rejecting the target spec.

Note that it's using this as the toolchain package, so it's quite possible that I messed something up or otherwise have introduced incompatibility with crane somehow. You can browse the repo here, and see the flake in question here.

Unfortunately, the flake is hard to meaningfully simplify because of the intrinsic complexity of targeting certain embedded devices.

To reproduce:

nix build github:Ben-PH/SimpleFOC-rs?ref=52cdf0169bb2d372e8b176d634abd1402c448292#esp32_sfoc

[ipetkov]

Hi @crabdancing thanks for the reproduction!

This looks like a configuration issue: although you've added esp-rust to the devshell, it isn't actually configured as the toolchain for the derivation. You'll likely need to fix one of the following:

• Set craneLib = (inputs.crane.mkLib pkgs).overrideToolchain esp-rust; here
• Use craneLibLLvmTools.buildPackage here (currently craneLibLLvmTools isn't used anywhere)

Hope this helps!

[crabdancing]

Thanks for the quick response @ipetkov! :) Sorry I missed that somewhat basic mistake.

After trying out the first one, I got this:

warning: Git tree '/home/ada/Projects/SimpleFOC-rs' is dirty
error: builder for '/nix/store/8a8rm2mrvj9w0qkcxr62549f7598khjg-esp32_sfoc-0.3.0.drv' failed with exit code 101;
       last 25 log lines:
       > Running phase: unpackPhase
       > unpacking source archive /nix/store/09qr3dj10s1a79y0ch9n9cjh9ymig5i9-source
       > source root is source
       > Running phase: patchPhase
       > code running
       > Executing configureCargoCommonVars
       > decompressing cargo artifacts from /nix/store/mrn53fzjr9785fbhrrpg2107bz0lk1m2-sfoc_rs-deps-0.3.0/target.tar.zst to target
       > Running phase: updateAutotoolsGnuConfigScriptsPhase
       > Running phase: configurePhase
       > will append /build/source/platforms/esp32_sfoc/.cargo-home/config.toml with contents of /nix/store/3r0znk0r9hzz62jxv9j1km09zkakmcan-vendor-cargo-deps/config.toml
       > default configurePhase, nothing to do
       > Running phase: buildPhase
       > ++ command cargo --version
       > cargo 1.79.0-nightly (ffa9cf99a 2024-06-03)
       > ++ command cargo build --release --message-format json-render-diagnostics -p esp32_sfoc
       > warning: profiles for the non root package will be ignored, specify profiles at the workspace root:
       > package:   /build/source/spinnies/esp32/original/Cargo.toml
       > workspace: /build/source/Cargo.toml
       > warning: profiles for the non root package will be ignored, specify profiles at the workspace root:
       > package:   /build/source/spinnies/esp32/s3/Cargo.toml
       > workspace: /build/source/Cargo.toml
       > error: no matching package named `compiler_builtins` found
       > location searched: registry `crates-io`
       > required by package `std v0.0.0 (/nix/store/d9r076qnij4h0b1dhm2hq1dchb59k1sp-esp-rs/lib/rustlib/src/rust/library/std)`
       >     ... which satisfies path dependency `std` (locked to 0.0.0) of package `sysroot v0.0.0 (/nix/store/d9r076qnij4h0b1dhm2hq1dchb59k1sp-esp-rs/lib/rustlib/src/rust/library/sysroot)`
       For full logs, run 'nix log /nix/store/8a8rm2mrvj9w0qkcxr62549f7598khjg-esp32_sfoc-0.3.0.drv'.

This also happens when using craneLibLLvmTools (see commit #63bec0fddb9491654176f0fdbbc2b276911ca704).

[ipetkov]

This is probably because the target does not come with a precompiled stdlib. Take a look at the build-std example on how to achieve that