Reexporting features implicitly enables optional dependency

[alecmocatta]

Problem

cargo check --features foo implicitly enables optional dependency bar given this manifest:

[features]
foo = ["bar/foo"]

[dependencies]
bar = { version = "0.1", path = "bar", optional = true }

The behaviour I would expect is bar not being enabled unless it's also specified in the --features.

If feature foo did in fact depend on bar, that could be specified like foo = ["bar", "bar/foo"].

Notes

Output of cargo version:

cargo 1.40.0-nightly (a429e8c 2019-10-04)

[ehuss]

Thanks for the report! This seems to be a duplicate of #3494, so I'm going to close in favor of that.