Repository navigation
unused_imports redundant import check false positive with dev-dependency #121684
Description
I tried this code:
Cargo.toml
[package]
name = "unused_import_bug-2024-02"
version = "0.1.0"
edition = "2021"
[features]
default = ["std"]
std = ["bitcoin/std", "bitcoin/secp-recovery" ]
[dependencies]
bitcoin = { version = "0.31.0", default-features = false }
[dev-dependencies]
secp256k1 = {version = "0.28.0", features = ["rand-std"]}src/main.rs
use bitcoin::secp256k1;
pub struct Thing(pub secp256k1::SecretKey);
fn main() {
println!("Hello, world!");
}If you compile this project with a recent nightly you will see the warning
Compiling unused_import_bug-2024-02 v0.1.0 (/store/home/apoelstra/code/tmp/unused_import_bug-2024-02)
warning: the item `secp256k1` is imported redundantly
--> src/main.rs:2:5
|
2 | use bitcoin::secp256k1;
| ^^^^^^^^^^^^^^^^^^ the item `secp256k1` is already defined here
|
= note: `#[warn(unused_imports)]` on by default
This warning should not show up, and if it must show up, it should say where the compiler thinks the "redundant import" actually is. Because there is only a single import.
If you comment out the [dev-dependencies] part of Cargo.toml the error goes away.
Activity
apoelstra commentedon Feb 27, 2024
Ok, what I think is going on is that when you run
cargo test, all the dev-dependencies are implicitly imported, meaning that your necessary-for-cargo buildimports become redundant.If this is expected behavior then the error message needs to be much clearer.
apoelstra commentedon Feb 27, 2024
Ok, I can mostly patch this by sticking
#[cfg(not(test))]onto all of my imports, but for examples this doesn't work. It seems like examples pull in dev-dependencies but do not havecfg(test)set.I can remove the import entirely, but then I am left with "example" code which does not actually compile outside of an example/ directory.
ci: screw up imports for rust-lang/rust#121684
ci: screw up imports for rust-lang/rust#121684
ci: screw up imports for rust-lang/rust#121684
Merge #645: remove sketchy `LikelyFalse` error
petrochenkov commentedon Mar 2, 2024
All
unusedlints work aftercfgs are expanded, this one is no different, so I'm going to close the issue.The recent extension of
unused_importshad some large effect on users in general, that is discussed in #121708 which is still open.ci: screw up imports for rust-lang/rust#121684
Merge rust-bitcoin/rust-miniscript#645: remove sketchy `LikelyFalse` …
Drop obsolete unused-import workaround
Drop obsolete unused-import workaround
Drop obsolete unused-import workaround
Merge #1001: Drop obsolete unused-import workaround