Feature-dependent dependencies are never selected

[jsgf]

Version

git master

Platform

all

Subcrates

• tokio-net
• tokio-executor

Description

tokio/Cargo.toml has:

[target.'cfg(feature = "tracing")'.dependencies]
tokio-net = { version = "=0.2.0-alpha.6", optional = true, path = "../tokio-net", features = ["tracing", "async-traits"] }
tokio-executor = { version = "=0.2.0-alpha.6", optional = true, path = "../tokio-executor", features = ["tracing"] }

According to Cargo's documentation, this does not work; the cfg(feature = "tracing") predicate will always evaluate to false. I think this only works because of the other unconditional dependency on tokio-net and tokio-executor above.

tokio-rs/tracing#365 is a related issue, and rust-lang/cargo#7442 is the Cargo issue which is mostly about lack of diagnostics for this issue.

[taiki-e]

Seems this was unintentionally fixed in #1680.
https://github.com/tokio-rs/tokio/pull/1680/files#diff-0a053cc4b37432b22b44e58a48f0ea81L83-L85