Support namespaced features

Author: taiki-e

CHANGELOG.md

@@ -10,6 +10,8 @@ Note: In this file, do not use the hard wrap in the middle of a sentence for com
 
 ## [Unreleased]
 
+- Support namespaced features (features with `dep:` prefix). ([#154](https://github.com/taiki-e/cargo-hack/pull/154))
+
 - Add metadata for cargo binstall.
 
 ## [0.5.14] - 2022-06-02

src/features.rs

@@ -19,9 +19,19 @@ impl Features {
 
         let mut features = Vec::with_capacity(package.features.len());
         let mut optional_deps = vec![];
+        let mut namespaced_features = vec![]; // features with `dep:` prefix
 
+        for names in package.features.values() {
+            for name in names {
+                if let Some(name) = name.strip_prefix("dep:") {
+                    namespaced_features.push(name);
+                }
+            }
+        }
         for name in package.optional_deps() {
-            optional_deps.push(name);
+            if !namespaced_features.contains(&name) {
+                optional_deps.push(name);
+            }
         }
         for name in package.features.keys() {
             if !optional_deps.contains(&&**name) {

tests/fixtures/namespaced_features/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "namespaced_features"
+version = "0.0.0"
+edition = "2021"
+publish = false
+
+[workspace]
+resolver = "2"
+
+[features]
+easytime = ["dep:easytime"]
+
+[dependencies]
+easytime = { version = "0.2", optional = true, default-features = false }
+
+[dev-dependencies]

tests/fixtures/namespaced_features/src/lib.rs

@@ -1393,3 +1393,15 @@ fn keep_going() {
             ",
         ));
 }
+
+#[test]
+fn namespaced_features() {
+    cargo_hack(["check", "--feature-powerset"])
+        .assert_success2("namespaced_features", Some(60))
+        .stderr_contains(
+            "
+            running `cargo check --no-default-features` on namespaced_features (1/2)
+            running `cargo check --no-default-features --features easytime` on namespaced_features (2/2)
+            ",
+        );
+}