Deduplicate entries in cargo --list

Fixes #6088

src/bin/cargo/cli.rs

@@ -98,21 +98,21 @@ Run with 'cargo -Z [FLAG] [SUBCOMMAND]'",
 
     if args.is_present("list") {
         drop_println!(config, "Installed Commands:");
-        for command in list_commands(config) {
+        for (name, command) in list_commands(config) {
             match command {
-                CommandInfo::BuiltIn { name, about } => {
+                CommandInfo::BuiltIn { about } => {
                     let summary = about.unwrap_or_default();
                     let summary = summary.lines().next().unwrap_or(&summary); // display only the first line
                     drop_println!(config, "    {:<20} {}", name, summary);
                 }
-                CommandInfo::External { name, path } => {
+                CommandInfo::External { path } => {
                     if is_verbose {
                         drop_println!(config, "    {:<20} {}", name, path.display());
                     } else {
                         drop_println!(config, "    {}", name);
                     }
                 }
-                CommandInfo::Alias { name, target } => {
+                CommandInfo::Alias { target } => {
                     drop_println!(config, "    {:<20} {}", name, target.iter().join(" "));
                 }
             }

src/bin/cargo/main.rs

@@ -8,7 +8,7 @@ use cargo::util::toml::StringOrVec;
 use cargo::util::CliError;
 use cargo::util::{self, closest_msg, command_prelude, CargoResult, CliResult, Config};
 use cargo_util::{ProcessBuilder, ProcessError};
-use std::collections::{BTreeMap, BTreeSet};
+use std::collections::BTreeMap;
 use std::env;
 use std::fs;
 use std::path::{Path, PathBuf};
@@ -84,10 +84,10 @@ fn aliased_command(config: &Config, command: &str) -> CargoResult<Option<Vec<Str
 }
 
 /// List all runnable commands
-fn list_commands(config: &Config) -> BTreeSet<CommandInfo> {
+fn list_commands(config: &Config) -> BTreeMap<String, CommandInfo> {
     let prefix = "cargo-";
     let suffix = env::consts::EXE_SUFFIX;
-    let mut commands = BTreeSet::new();
+    let mut commands = BTreeMap::new();
     for dir in search_directories(config) {
         let entries = match fs::read_dir(dir) {
             Ok(entries) => entries,
@@ -104,37 +104,43 @@ fn list_commands(config: &Config) -> BTreeSet<CommandInfo> {
             }
             if is_executable(entry.path()) {
                 let end = filename.len() - suffix.len();
-                commands.insert(CommandInfo::External {
-                    name: filename[prefix.len()..end].to_string(),
-                    path: path.clone(),
-                });
+                commands.insert(
+                    filename[prefix.len()..end].to_string(),
+                    CommandInfo::External { path: path.clone() },
+                );
             }
         }
     }
 
     for cmd in commands::builtin() {
-        commands.insert(CommandInfo::BuiltIn {
-            name: cmd.get_name().to_string(),
-            about: cmd.p.meta.about.map(|s| s.to_string()),
-        });
+        commands.insert(
+            cmd.get_name().to_string(),
+            CommandInfo::BuiltIn {
+                about: cmd.p.meta.about.map(|s| s.to_string()),
+            },
+        );
     }
 
     // Add the builtin_aliases and them descriptions to the
-    // `commands` `BTreeSet`.
+    // `commands` `BTreeMap`.
     for command in &BUILTIN_ALIASES {
-        commands.insert(CommandInfo::BuiltIn {
-            name: command.0.to_string(),
-            about: Some(command.2.to_string()),
-        });
+        commands.insert(
+            command.0.to_string(),
+            CommandInfo::BuiltIn {
+                about: Some(command.2.to_string()),
+            },
+        );
     }
 
     // Add the user-defined aliases
     if let Ok(aliases) = config.get::<BTreeMap<String, StringOrVec>>("alias") {
         for (name, target) in aliases.iter() {
-            commands.insert(CommandInfo::Alias {
-                name: name.to_string(),
-                target: target.clone(),
-            });
+            commands.insert(
+                name.to_string(),
+                CommandInfo::Alias {
+                    target: target.clone(),
+                },
+            );
         }
     }
 
@@ -150,11 +156,8 @@ fn execute_external_subcommand(config: &Config, cmd: &str, args: &[&str]) -> Cli
     let command = match path {
         Some(command) => command,
         None => {
-            let suggestions: Vec<_> = list_commands(config)
-                .iter()
-                .map(|c| c.name().to_string())
-                .collect();
-            let did_you_mean = closest_msg(cmd, suggestions.iter(), |c| c);
+            let suggestions = list_commands(config);
+            let did_you_mean = closest_msg(cmd, suggestions.keys(), |c| c);
             let err = anyhow::format_err!("no such subcommand: `{}`{}", cmd, did_you_mean);
             return Err(CliError::new(err, 101));
         }

src/cargo/util/command_prelude.rs

@@ -718,17 +718,7 @@ pub fn values_os(args: &ArgMatches<'_>, name: &str) -> Vec<OsString> {
 
 #[derive(PartialEq, Eq, PartialOrd, Ord)]
 pub enum CommandInfo {
-    BuiltIn { name: String, about: Option<String> },
-    External { name: String, path: PathBuf },
-    Alias { name: String, target: StringOrVec },
-}
-
-impl CommandInfo {
-    pub fn name(&self) -> &str {
-        match self {
-            CommandInfo::BuiltIn { name, .. } => name,
-            CommandInfo::External { name, .. } => name,
-            CommandInfo::Alias { name, .. } => name,
-        }
-    }
+    BuiltIn { about: Option<String> },
+    External { path: PathBuf },
+    Alias { target: StringOrVec },
 }

tests/testsuite/cargo_command.rs

@@ -61,6 +61,24 @@ fn list_custom_aliases_with_descriptions() {
         .run();
 }
 
+#[cargo_test]
+fn list_dedupe() {
+    let p = project()
+        .executable(Path::new("path-test-1").join("cargo-dupe"), "")
+        .executable(Path::new("path-test-2").join("cargo-dupe"), "")
+        .build();
+
+    let mut path = path();
+    path.push(p.root().join("path-test-1"));
+    path.push(p.root().join("path-test-2"));
+    let path = env::join_paths(path.iter()).unwrap();
+
+    p.cargo("--list")
+        .env("PATH", &path)
+        .with_stdout_contains_n("    dupe", 1)
+        .run();
+}
+
 #[cargo_test]
 fn list_command_looks_at_path() {
     let proj = project()