cargo workspace是个比较优雅的方案

建议直接分两个crate，然后用一个shell脚本来控制，简单易懂。什么都只用一个cargo来做，实在没有必要。

[[bin]]
name = 'banary-a'
path = 'src/a.rs'
required-features = ['feature-a']

[[bin]]
name = 'banary-b'
path = 'src/b.rs'
required-features = ['feature-b']

cargo b --release --features feature-a cargo b --release --features feature-b

https://doc.rust-lang.org/cargo/reference/cargo-targets.html#binaries

不知道能不能满足需求。