feature-scope

Introduction

A helper library that enables workspace crates to independently control their required features without cross-package interference.

Still in development, the API may change in the future.

Quick Start

You must set the package.metadata.feature-scope in your Cargo.toml file first. It's a table like features but with a different purpose. Each crates in the workspace can have its own package.metadata.feature-scope table, and the features listed in it will be used to control the visibility of the macros in this crate.

[package.metadata.feature-scope]
default = ["a"]
a = []
b = []
c = []

This library depends on the build.rs to provide the arguments to the compiler. You needs to call load function inside the crate like this:

// build.rs

fn main() {
    // Load the feature scope from the Cargo.toml file.
    feature_scope::load().unwrap();
}

Then, you can use the feature_scope macro in your code:

// The default feature is `a`, so this function will be available when the `a` feature is enabled.
#[feature_scope(a)]
pub fn basic_expand() {
    println!("feature_scope_a");
}

#[feature_scope(any(b, c))]
pub fn basic_expand() {
    println!("feature_scope_b_or_c");
}

#[feature_scope(only(a, b, c))]
compile_error! {
    // This will cause a compile error if all features are enabled.
    "This should not be compiled!"
}


// prints "feature_scope_a" or "feature_scope_b_c" depending on the feature flag set in Cargo.toml
basic_expand();