distinguish between normal dependency and dev-dependency

[Sherlock-Holo]

I use libc in unit test and doc example, but not use in codes. When I let libc under [dependencies], udeps doesn't realize it is unnecessary.

Could you make udeps distinguish dependency between normal dependency and dev-dependency so we can write [dependencies] more precisely.

[est31]

The only info cargo-udeps has access to is "was this library used in the build". And as we are basically doing a dev build of the library, dev-dependencies are included. We'd have to build the library twice, once a dev build to check the dev-dependencies, and once a non-dev build to check any normal dependencies that might only be used as dev-dependencies. It's doable but makes running cargo-udeps a bit slower.

[Sherlock-Holo]

maybe can add an option like --accurate to make a full scan to check any normal dependencies that might only be used as dev-dependencies? Without this option, only check one times to speed up?

[qryxip]

You can find such dependencies with cargo +nightly udeps && cargo +nightly udeps --all-targets because cargo-udeps currently skips dependencies that are not appear in the rustc options.

[dependencies]
if_chain = "1.0.0"

[dev-dependencies]

fn main() {
    todo!();
}

#[cfg(test)]
mod tests {
    use if_chain as _;
}

$ cargo +nightly udeps
    Checking aaaaa v0.0.0 (/home/ryo/src/local/scripts/rs/aaaaa)
    Finished dev [unoptimized + debuginfo] target(s) in 0.11s
info: Loading save analysis from "/home/ryo/src/local/scripts/rs/target/debug/deps/save-analysis/aaaaa-38d512ac7a9caa23.json"
unused dependencies:
`aaaaa v0.0.0 (/home/ryo/src/local/scripts/rs/aaaaa)`
└─── dependencies
     └─── "if_chain"
Note: These dependencies might be used by other targets.
      To find dependencies that are not used by any target, enable `--all-targets`.
Note: They might be false-positive.
      For example, `cargo-udeps` cannot detect usage of crates that are only used in doc-tests.
      To ignore some of dependencies, write `package.metadata.cargo-udeps.ignore` in Cargo.toml.
$ echo "$?"
1

But it may be a good idea to add an option like --accurate.

We can add --output pretty or something as well.

`package v0.0.0 (/path/to/package)`
├─── dependencies
│    ├─── `library_a` ✓ Used.
│    │                1/1 lib,
│    │                1/1 lib (profile=test),
│    │                1/1 bin(s),
│    │                1/1 bin(s) (profile=test),
│    │                0/0 example(s),
│    │                5/5 test(s)
│    ├─── `library_b` ✓ Used. (ignored)
│    │                0/0 lib,
│    │                0/0 lib (profile=test),
│    │                0/0 bin(s),
│    │                0/0 bin(s) (profile=test),
│    │                0/0 example(s),
│    │                0/0 test(s)
│    ├─── `library_c` ✗ Unused. (requested with `--accurate`)
│    │                0/0 lib,
│    │                1/1 lib (profile=test),
│    │                0/0 bin(s),
│    │                1/1 bin(s) (profile=test),
│    │                0/0 example(s),
│    │                5/5 test(s)
│    ├─── `library_d` ✗ Unused.
│    │                0/0 lib,
│    │                0/0 lib (profile=test),
│    │                0/0 bin(s),
│    │                0/0 bin(s) (profile=test),
│    │                0/0 example(s),
│    │                0/0 test(s)
└─── build-dependencies
     └─── `library_e` ✓ Used.
                      1/1 build-script