feat(add): suggest similarly named features (#15438)

### What does this PR try to resolve?
Fixes #15436

### How should we test and review this PR?
There are 3 tests for each test case:
- there are no feature suggestions
- there's only one feature suggestion (most common)
- there are several feature suggestions

Author: epage

src/cargo/ops/cargo_add/mod.rs

@@ -29,6 +29,7 @@ use crate::core::Summary;
 use crate::core::Workspace;
 use crate::sources::source::QueryKind;
 use crate::util::cache_lock::CacheLockMode;
+use crate::util::edit_distance;
 use crate::util::style;
 use crate::util::toml::lookup_path_base;
 use crate::util::toml_mut::dependency::Dependency;
@@ -159,19 +160,32 @@ pub fn add(workspace: &Workspace<'_>, options: &AddOptions<'_>) -> CargoResult<(
             activated.retain(|f| !unknown_features.contains(f));
 
             let mut message = format!(
-                "unrecognized feature{} for crate {}: {}\n",
+                "unrecognized feature{} for crate {}: {}",
                 if unknown_features.len() == 1 { "" } else { "s" },
                 dep.name,
                 unknown_features.iter().format(", "),
             );
             if activated.is_empty() && deactivated.is_empty() {
-                write!(message, "no features available for crate {}", dep.name)?;
+                write!(message, "\n\nno features available for crate {}", dep.name)?;
             } else {
-                if !deactivated.is_empty() {
+                let mut suggested = false;
+                for unknown_feature in &unknown_features {
+                    let suggestion = edit_distance::closest_msg(
+                        unknown_feature,
+                        deactivated.iter().chain(activated.iter()),
+                        |dep| *dep,
+                        "feature",
+                    );
+                    if !suggestion.is_empty() {
+                        write!(message, "{suggestion}")?;
+                        suggested = true;
+                    }
+                }
+                if !deactivated.is_empty() && !suggested {
                     if deactivated.len() <= MAX_FEATURE_PRINTS {
-                        writeln!(
+                        write!(
                             message,
-                            "disabled features:\n    {}",
+                            "\n\ndisabled features:\n    {}",
                             deactivated
                                 .iter()
                                 .map(|s| s.to_string())
@@ -184,14 +198,18 @@ pub fn add(workspace: &Workspace<'_>, options: &AddOptions<'_>) -> CargoResult<(
                                 .format("\n    ")
                         )?;
                     } else {
-                        writeln!(message, "{} disabled features available", deactivated.len())?;
+                        write!(
+                            message,
+                            "\n\n{} disabled features available",
+                            deactivated.len()
+                        )?;
                     }
                 }
-                if !activated.is_empty() {
+                if !activated.is_empty() && !suggested {
                     if deactivated.len() + activated.len() <= MAX_FEATURE_PRINTS {
                         writeln!(
                             message,
-                            "enabled features:\n    {}",
+                            "\n\nenabled features:\n    {}",
                             activated
                                 .iter()
                                 .map(|s| s.to_string())
@@ -204,7 +222,11 @@ pub fn add(workspace: &Workspace<'_>, options: &AddOptions<'_>) -> CargoResult<(
                                 .format("\n    ")
                         )?;
                     } else {
-                        writeln!(message, "{} enabled features available", activated.len())?;
+                        writeln!(
+                            message,
+                            "\n\n{} enabled features available",
+                            activated.len()
+                        )?;
                     }
                 }
             }

tests/testsuite/cargo_add/feature_suggestion_multiple/in/Cargo.toml

@@ -0,0 +1,7 @@
+[workspace]
+
+[package]
+name = "cargo-list-test-fixture"
+version = "0.0.0"
+edition = "2024"
+

tests/testsuite/cargo_add/feature_suggestion_multiple/in/src/lib.rs

@@ -0,0 +1,24 @@
+use cargo_test_support::current_dir;
+use cargo_test_support::file;
+use cargo_test_support::prelude::*;
+use cargo_test_support::Project;
+
+#[cargo_test]
+fn case() {
+    let project = Project::from_template(current_dir!().join("in"));
+    let project_root = project.root();
+    let cwd = &project_root;
+
+    cargo_test_support::registry::Package::new("my-package", "0.1.0+my-package")
+        .feature("bar", &[])
+        .feature("foo", &[])
+        .publish();
+
+    snapbox::cmd::Command::cargo_ui()
+        .arg("add")
+        .arg_line("my-package --features baz --features feo")
+        .current_dir(cwd)
+        .assert()
+        .failure()
+        .stderr_eq(file!["stderr.term.svg"]);
+}

tests/testsuite/cargo_add/feature_suggestion_multiple/mod.rs

@@ -0,0 +1,7 @@
+[workspace]
+
+[package]
+name = "cargo-list-test-fixture"
+version = "0.0.0"
+edition = "2024"
+

tests/testsuite/cargo_add/feature_suggestion_multiple/stderr.term.svg

@@ -0,0 +1,24 @@
+use cargo_test_support::current_dir;
+use cargo_test_support::file;
+use cargo_test_support::prelude::*;
+use cargo_test_support::Project;
+
+#[cargo_test]
+fn case() {
+    let project = Project::from_template(current_dir!().join("in"));
+    let project_root = project.root();
+    let cwd = &project_root;
+
+    cargo_test_support::registry::Package::new("my-package", "0.1.0+my-package")
+        .feature("bar", &[])
+        .feature("foo", &[])
+        .publish();
+
+    snapbox::cmd::Command::cargo_ui()
+        .arg("add")
+        .arg_line("my-package --features none_existent")
+        .current_dir(cwd)
+        .assert()
+        .failure()
+        .stderr_eq(file!["stderr.term.svg"]);
+}

tests/testsuite/cargo_add/feature_suggestion_none/in/Cargo.toml

@@ -0,0 +1,7 @@
+[workspace]
+
+[package]
+name = "cargo-list-test-fixture"
+version = "0.0.0"
+edition = "2024"
+

tests/testsuite/cargo_add/feature_suggestion_none/in/src/lib.rs

@@ -0,0 +1,23 @@
+use cargo_test_support::current_dir;
+use cargo_test_support::file;
+use cargo_test_support::prelude::*;
+use cargo_test_support::Project;
+
+#[cargo_test]
+fn case() {
+    let project = Project::from_template(current_dir!().join("in"));
+    let project_root = project.root();
+    let cwd = &project_root;
+
+    cargo_test_support::registry::Package::new("my-package", "0.1.0+my-package")
+        .feature("bar", &[])
+        .publish();
+
+    snapbox::cmd::Command::cargo_ui()
+        .arg("add")
+        .arg_line("my-package --features baz")
+        .current_dir(cwd)
+        .assert()
+        .failure()
+        .stderr_eq(file!["stderr.term.svg"]);
+}

tests/testsuite/cargo_add/feature_suggestion_none/mod.rs

@@ -21,6 +21,9 @@ mod dev_existing_path_base;
 mod dev_prefer_existing_version;
 mod dry_run;
 mod empty_dep_name;
+mod feature_suggestion_multiple;
+mod feature_suggestion_none;
+mod feature_suggestion_single;
 mod features;
 mod features_activated_over_limit;
 mod features_deactivated_over_limit;