Breaking endless loop on cyclic features in added dependency in cargo-add

src/cargo/ops/cargo_add/mod.rs

@@ -726,7 +726,8 @@ impl DependencyUI {
                     .get(next)
                     .into_iter()
                     .flatten()
-                    .map(|s| s.as_str()),
+                    .map(|s| s.as_str())
+                    .filter(|s| !activated.contains(s)),
             );
             activated.extend(
                 self.available_features

tests/testsuite/cargo_add/cyclic_features/in

@@ -0,0 +1 @@
+../add-basic.in

tests/testsuite/cargo_add/cyclic_features/mod.rs

@@ -0,0 +1,25 @@
+use cargo_test_support::compare::assert_ui;
+use cargo_test_support::prelude::*;
+use cargo_test_support::Project;
+
+use crate::cargo_add::init_registry;
+use cargo_test_support::curr_dir;
+
+#[cargo_test]
+fn case() {
+    init_registry();
+    let project = Project::from_template(curr_dir!().join("in"));
+    let project_root = project.root();
+    let cwd = &project_root;
+
+    snapbox::cmd::Command::cargo_ui()
+        .arg("add")
+        .arg_line("test_cyclic_features")
+        .current_dir(cwd)
+        .assert()
+        .success()
+        .stdout_matches_path(curr_dir!().join("stdout.log"))
+        .stderr_matches_path(curr_dir!().join("stderr.log"));
+
+    assert_ui().subset_matches(curr_dir!().join("out"), &project_root);
+}

tests/testsuite/cargo_add/cyclic_features/out/Cargo.toml

@@ -0,0 +1,8 @@
+[workspace]
+
+[package]
+name = "cargo-list-test-fixture"
+version = "0.0.0"
+
+[dependencies]
+test_cyclic_features = "0.1.1"

tests/testsuite/cargo_add/cyclic_features/stderr.log

@@ -0,0 +1,5 @@
+    Updating `dummy-registry` index
+      Adding test_cyclic_features v0.1.1 to dependencies.
+             Features:
+             + feature-one
+             + feature-two

tests/testsuite/cargo_add/mod.rs

@@ -4,6 +4,7 @@ mod add_normalized_name_external;
 mod build;
 mod build_prefer_existing_version;
 mod change_rename_target;
+mod cyclic_features;
 mod default_features;
 mod deprecated_default_features;
 mod deprecated_section;
@@ -165,6 +166,12 @@ fn add_registry_packages(alt: bool) {
     cargo_test_support::registry::Package::new("test_nonbreaking", "0.1.1")
         .alternative(alt)
         .publish();
+    cargo_test_support::registry::Package::new("test_cyclic_features", "0.1.1")
+        .alternative(alt)
+        .feature("default", &["feature-one", "feature-two"])
+        .feature("feature-one", &["feature-two"])
+        .feature("feature-two", &["feature-one"])
+        .publish();
 
     // Normalization
     cargo_test_support::registry::Package::new("linked-hash-map", "0.5.4")