Problem with a rust build (crane/fenix)

blaggacao · February 25, 2023, 10:09pm

This is what effectively “fixes” it: fix: CARGO_HOME needs be set to stop the bleed from $HOME/.cargo · paisano-nix/mdbook-paisano-preprocessor@fffe203 · GitHub

It comes at the cost that the packages cache and indexes and all other things need to be kept in $PRJ_DATA_DIR/cargo, so first time using cargo needs a bit of downloading to that folder.

Overall, this issue is probably a typical one for an on-boarding story when the user already has been using the cargo toolchain in the traditional way (and likely didn’t clean up to try out Nix based workflows).

figsoda · February 25, 2023, 10:44pm

There is an upstream rust issue for this

github.com/rust-lang/cargo

Can't provide custom subcommand in $PATH if it also exists in $CARGO_HOME/bin

opened 02:40PM - 01 Jan 19 UTC

TimNN

C-bug A-custom-subcommands

**Problem** Cargo will _always_ search `$CARGO_HOME/bin` **first** for cu…stom subcommands. This means that testing subcommands (e.g. using `PATH="$PWD/target/debug:$PATH" cargo my-command`) won't work if `cargo-my-command` is also installed in `$CARGO_HOME/bin`. **Steps** ```sh # Step 1: Prepare a dummy command on `$PATH`. mkdir -p "cargo-foo-bin" echo -e '#!/bin/bash\necho "From Path."' > "cargo-foo-bin/cargo-foo" chmod +x "cargo-foo-bin/cargo-foo" # Step 2: Run the dummy command. It is correctly found in `$PATH`. PATH="$PWD/cargo-foo-bin:$PATH" cargo foo # Step 3: Prepare the same command in `$CARGO_HOME/bin`. echo -e '#!/bin/bash\necho "Installed."'> "${CARGO_HOME:-$HOME/.cargo}/bin/cargo-foo" chmod +x "${CARGO_HOME:-$HOME/.cargo}/bin/cargo-foo" # Step 4: Run the dummy command. The version from `$CARGO_HOME/bin` is used. PATH="$PWD/cargo-foo-bin:$PATH" cargo foo ``` **Possible Solution(s)** * Use `$CARGO_HOME/bin` as a fallback location rather than the primary location **`[breaking-change]`**. * Allow overriding subcommand binaries with environment variables, eg. `$CARGO_MY_COMMAND=...` **`[breaking-change]`**. **Notes** Output of `cargo version`: `cargo 1.31.0 (339d9f9c8 2018-11-16)` Behavior introduced in #2192.

(Thanks @CobaltCause for linking me this in the nix rust matrix)

CobaltCause · February 25, 2023, 11:28pm

You’re welcome! I didn’t have an account here before but I do now.

In general, if you can create a new place for $CARGO_HOME to live impurely, then you should also be able to symlink the right places back to the “real” one so you can still share the package cache and registry across all local projects. This does have the drawback of anything in your original $CARGO_HOME/bin no longer working the same, but if you’re using Nix then it’s pretty unlikely you have non-rust-toolchain tools in there anyway.

It’ll also bite you in certain CI systems; I first noticed this when trying to run a project’s CI in GitHub Actions because ubuntu-latest comes with a bunch of stuff pre-installed, including a rust toolchain. So, watch out for that too.