How to pass compiler flags to a sub crate in Rust?

Question

I have the crates A and B. A depends on B and B has a feature named some_feature.

I can build B using cargo by running cargo build --features=some_feature, but how can I set the same features for A that I can choose to enable or disable some_feature for underlying crate B when compiling A?

Answer 1

You can simply forward the feature specified in A:

# A/Cargo.toml

[features]
some-feature = ["B/some-feature"]

[dependencies]
B = "*"

This will compile B with --features=some_feature if you pass --features=some_feature to A.

Answer 2

You just need to configure the manifest, it's as simple as the doc say:

[dependencies.awesome]
version = "1.3.5"
default-features = false # do not include the default features, and optionally
                         # cherry-pick individual features
features = ["secure-password", "civet"]