default-features = false not respected at compile time

[nrdxp]

I am currently in the process of attempting to use cargo2nix to build substrate, and I've ran into a confusing snag. I have a dependency specified here:
https://github.com/paritytech/substrate/blob/polkadot-v0.9.40/client/cli/Cargo.toml#L23

It is important that this flag is respected otherwise the crate compile fails, because a required feature dependency is not included. consequently I am hitting a build failure where it is trying to compile the names cli and failing to find the clap dependency. Of course this shouldn't be an issue as substrate only uses names as a lib, and the docs explicitly mention to disable default features when used as such.

I am a bit confused however, as I was able to set NIX_DEBUG in an override for the crate and I saw that cargo was indeed passing the --no-default-features flag, however the crate still attempts to build the cli and fails for some reason. Not sure if this is a mixup between cargo and rustc, but I'm not 100% sure if I can fix it, or if this needs to move further upstream.

[psionic-k]

If you search around for features issues, the feature behavior is not very complete when platform dependencies exist.

Check your Cargo.nix for the offending feature being passed in.

Newer versions (try release-maintenance-branch) of cargo2nix do this properly already though.