Difference between running `cargo run -p` and `cargo run --bin` when running from workspace?

parkellipsen · November 6, 2024, 11:42am

Hi,

I'm having a complex project with a root folder, a Cargo.toml defining a workspace, and a few crates.

Two crates have features that aren't activated by default, only in one of the crates they are.

When I try to run one of the sub-crates (a binary) with cargo run --bin ... from the workspace folder, the feature is activated, compilation fails.

If I run cargo run -p .. from the workspace folder, compilation succeeds. This seems rather confusing ...

Does anyone have a hint?

Best,
N

kornel · November 6, 2024, 12:23pm

This is a quirk of Cargo:

github.com/rust-lang/cargo

Feature selection in workspace depends on the set of packages compiled

opened 06:27AM - 03 Sep 17 UTC

matklad

C-bug A-features E-hard A-workspaces S-needs-design

Maintainers notes - The recompilation was fixed, but this issue is still open …regarding having features change based on what is being built simultaneously. - The `cargo hack` plugin will automatically expand `cargo check --workspace` (etc) to `cargo check -p fail_test && cargo check -p lang_rust && ...`, --- Reproduction: 1. Check out this commit: https://github.com/matklad/fall/commit/3022be495a8523ca43c3d78ab29966fbb5ee69fd 2. Build some test with `cargo test -p fall_test -p fall_test -p lang_rust -p lang_rust -p lang_json --verbose --no-run` 3. Build other tests with `cargo test --all --verbose --no-run` 4. Run `cargo test -p fall_test -p fall_test -p lang_rust -p lang_rust -p lang_json --verbose --no-run` again and observe that `memchr` and some other dependencies are recompiled. 5. Run `cargo test --all --verbose --no-run` and observe `memchr` recompiled again. The verbose flag gives the following commands for `memchr`: ``` Running `rustc --crate-name memchr /home/matklad/trash/registry/src/github.com-1ecc6299db9ec823/memchr-1.0.1/src/lib.rs --crate-type lib --emit=dep-info,link -C debuginfo=2 --cfg 'feature="default"' --cfg 'feature="libc"' --cfg 'feature="use_std"' -C metadata=be49c4722e8b48bf -C extra-filename=-be49c4722e8b48bf --out-dir /home/matklad/trash/fall/target/debug/deps -L dependency=/home/matklad/trash/fall/target/debug/deps --extern libc=/home/matklad/trash/fall/target/debug/deps/liblibc-90ba32719d46f457.rlib --cap-lints allow -C target-cpu=native` Running `rustc --crate-name memchr /home/matklad/trash/registry/src/github.com-1ecc6299db9ec823/memchr-1.0.1/src/lib.rs --crate-type lib --emit=dep-info,link -C debuginfo=2 --cfg 'feature="default"' --cfg 'feature="libc"' --cfg 'feature="use_std"' -C metadata=be49c4722e8b48bf -C extra-filename=-be49c4722e8b48bf --out-dir /home/matklad/trash/fall/target/debug/deps -L dependency=/home/matklad/trash/fall/target/debug/deps --extern libc=/home/matklad/trash/fall/target/debug/deps/liblibc-335251832eb2b7ec.rlib --cap-lints allow -C target-cpu=native` ``` Here's the single difference: ``` --extern libc=/home/matklad/trash/fall/target/debug/deps/liblibc-90ba32719d46f457.rlib --extern libc=/home/matklad/trash/fall/target/debug/deps/liblibc-335251832eb2b7ec.rlib ``` Versions (whyyyyy cargo is 0.21 and rustc is 1.20??? This is soo confusing) ``` λ cargo --version --verbose cargo 0.21.0 (5b4b8b2ae 2017-08-12) release: 0.21.0 commit-hash: 5b4b8b2ae3f6a884099544ce66dbb41626110ece commit-date: 2017-08-12 ~/trash/fall master λ rustc --version rustc 1.20.0 (f3d6973f4 2017-08-27) ```

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Difference between running `cargo run -p` and `cargo run --bin` when running from workspace?

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