From 8f58bb08214d233649f87bb7b64c5bd5a133ba19 Mon Sep 17 00:00:00 2001
From: Dale Wijnand <dale.wijnand@gmail.com>
Date: Thu, 14 Feb 2019 21:25:39 +0000
Subject: [PATCH] Add Listing of Installed Components

This feature adds the ability to only list installed components
rather than all available components.
---
 src/rustup-cli/common.rs      | 24 +++++++++++++++++-------
 src/rustup-cli/rustup_mode.rs | 11 ++++++++++-
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/src/rustup-cli/common.rs b/src/rustup-cli/common.rs
index a6a04474eb..d4ee5d038c 100644
--- a/src/rustup-cli/common.rs
+++ b/src/rustup-cli/common.rs
@@ -323,21 +323,31 @@ pub fn list_components(toolchain: &Toolchain<'_>) -> Result<()> {
     for component in toolchain.list_components()? {
         let name = component.name;
         if component.required {
-            let _ = t.attr(term2::Attr::Bold);
-            let _ = writeln!(t, "{} (default)", name);
-            let _ = t.reset();
+            t.attr(term2::Attr::Bold)?;
+            writeln!(t, "{} (default)", name)?;
+            t.reset()?;
         } else if component.installed {
-            let _ = t.attr(term2::Attr::Bold);
-            let _ = writeln!(t, "{} (installed)", name);
-            let _ = t.reset();
+            t.attr(term2::Attr::Bold)?;
+            writeln!(t, "{} (installed)", name)?;
+            t.reset()?;
         } else if component.available {
-            let _ = writeln!(t, "{}", name);
+            writeln!(t, "{}", name)?;
         }
     }
 
     Ok(())
 }
 
+pub fn list_installed_components(toolchain: &Toolchain<'_>) -> Result<()> {
+    let mut t = term2::stdout();
+    for component in toolchain.list_components()? {
+        if component.installed {
+            writeln!(t, "{}", component.name)?;
+        }
+    }
+    Ok(())
+}
+
 pub fn list_toolchains(cfg: &Cfg) -> Result<()> {
     let toolchains = cfg.list_toolchains()?;
 
diff --git a/src/rustup-cli/rustup_mode.rs b/src/rustup-cli/rustup_mode.rs
index b923657a02..64104ad31e 100644
--- a/src/rustup-cli/rustup_mode.rs
+++ b/src/rustup-cli/rustup_mode.rs
@@ -293,6 +293,11 @@ pub fn cli() -> App<'static, 'static> {
                 .subcommand(
                     SubCommand::with_name("list")
                         .about("List installed and available components")
+                        .arg(
+                            Arg::with_name("installed")
+                                .long("--installed")
+                                .help("List only installed components"),
+                        )
                         .arg(
                             Arg::with_name("toolchain")
                                 .help(TOOLCHAIN_ARG_HELP)
@@ -823,7 +828,11 @@ fn target_remove(cfg: &Cfg, m: &ArgMatches<'_>) -> Result<()> {
 fn component_list(cfg: &Cfg, m: &ArgMatches<'_>) -> Result<()> {
     let toolchain = explicit_or_dir_toolchain(cfg, m)?;
 
-    common::list_components(&toolchain)
+    if m.is_present("installed") {
+        common::list_installed_components(&toolchain)
+    } else {
+        common::list_components(&toolchain)
+    }
 }
 
 fn component_add(cfg: &Cfg, m: &ArgMatches<'_>) -> Result<()> {