Cargo check has false negatives in a workspace with internal dependencies

[Wodann]

Problem

When using a workspace that has multiple crates that depend on each other, enabling of feature flags prevents running of cargo check --no-default-features on all crates.

Steps

Example workspace:

• crates
  • A [features: Foo]
  • B [depends on: A with feature Foo enabled]

Running

cargo c --no-default-features

inside {workspace-dir}/crates/A will cause errors when anything that should be hidden behind the Foo feature flag is referenced

cargo c --no-default-features --all

inside {workspace-dir} does not cause any errors.

Possible Solution(s)

I'd potentially expect two version of A to be checked:

• One that complies with the cargo check --no-default-features command
• One that suffices the dependency for B (Foo enabled)

Notes

No response

Version

cargo 1.70.0 (ec8a8a0ca 2023-04-25)
release: 1.70.0
commit-hash: ec8a8a0cabb0e0cadef58902470f6c7ee7868bdc
commit-date: 2023-04-25
host: x86_64-pc-windows-msvc
libgit2: 1.6.3 (sys:0.17.0 vendored)
libcurl: 8.0.1-DEV (sys:0.4.61+curl-8.0.1 vendored ssl:Schannel)
os: Windows 10.0.22621 (Windows 10 Home) [64-bit]

[epage]

We generally refer to this as "feature unification" and this is expected. When only do one build combination within a run. I believe #4463 is the most relevant existing issue for this.

One workaround is to use tools like cargo-hack to do multiple cargo check runs.

Going to go ahead and close this but if there is something I missed, let us know and we can re-open it!

[weihanglo]

For more on feature unification, see https://doc.rust-lang.org/cargo/reference/features.html#feature-unification