From 4689949cff96e99fe8ea2d60841fea07676739b9 Mon Sep 17 00:00:00 2001
From: Shupeng Xue <dspxue@gmail.com>
Date: Tue, 25 Jun 2024 13:17:40 +1000
Subject: [PATCH 1/2] apply smart guess to `rustup update/uninstall self`

Use original error instead of rewriting

avoid duplicate `.to_string()`

remove unnecessary `.as_str()`
---
 src/cli/rustup_mode.rs | 11 ++++++++++-
 src/toolchain.rs       |  6 ++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/cli/rustup_mode.rs b/src/cli/rustup_mode.rs
index 5de45f0760..34baeae19b 100644
--- a/src/cli/rustup_mode.rs
+++ b/src/cli/rustup_mode.rs
@@ -3,6 +3,7 @@ use std::fmt;
 use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::ExitStatus;
+use std::str::FromStr;
 
 use anyhow::{anyhow, Error, Result};
 use clap::{builder::PossibleValue, Args, CommandFactory, Parser, Subcommand, ValueEnum};
@@ -135,7 +136,7 @@ enum RustupSubcmd {
     )]
     Update {
         /// Toolchain name, such as 'stable', 'nightly', or '1.8.0'. For more information see `rustup help toolchain`
-        #[arg(num_args = 1..)]
+        #[arg(num_args = 1.., value_parser = update_toolchain_value_parser)]
         toolchain: Vec<PartialToolchainDesc>,
 
         /// Don't perform self update when running the `rustup update` command
@@ -258,6 +259,14 @@ enum RustupSubcmd {
     },
 }
 
+fn update_toolchain_value_parser(s: &str) -> Result<PartialToolchainDesc> {
+    PartialToolchainDesc::from_str(s).inspect_err(|_| {
+        if s == "self" {
+            info!("if you meant to update rustup itself, use `rustup self update`");
+        }
+    })
+}
+
 #[derive(Debug, Subcommand)]
 enum ShowSubcmd {
     /// Show the active toolchain
diff --git a/src/toolchain.rs b/src/toolchain.rs
index 6d3c8cb2fd..6c995cba7c 100644
--- a/src/toolchain.rs
+++ b/src/toolchain.rs
@@ -457,7 +457,13 @@ impl<'a> Toolchain<'a> {
                     fs::remove_dir_all(&path)?;
                     true
                 } else {
+                    let name = name.to_string();
                     info!("no toolchain installed for '{name}'");
+                    if name == "self" {
+                        info!(
+                            "if you meant to uninstall rustup itself, use `rustup self uninstall`"
+                        );
+                    }
                     false
                 }
             }

From 1f9f1daf848a5260074233fe56948eaff23a4260 Mon Sep 17 00:00:00 2001
From: Xerxes-2 <dspxue@gmail.com>
Date: Wed, 26 Jun 2024 17:51:49 +1000
Subject: [PATCH 2/2] add regression tests for smart guess

---
 tests/suite/cli_misc.rs | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/tests/suite/cli_misc.rs b/tests/suite/cli_misc.rs
index 5359e6afbd..3dee46f337 100644
--- a/tests/suite/cli_misc.rs
+++ b/tests/suite/cli_misc.rs
@@ -1180,3 +1180,27 @@ async fn toolchain_link_then_list_verbose() {
         .expect_stdout_ok(&["rustup", "toolchain", "list", "-v"], "/custom-1")
         .await;
 }
+
+#[tokio::test]
+async fn update_self_smart_guess() {
+    let cx = CliTestContext::new(Scenario::SimpleV2).await;
+    let out = cx.config.run("rustup", &["update", "self"], &[]).await;
+    let invalid_toolchain = out.stderr.contains("invalid toolchain name");
+    if !out.ok && invalid_toolchain {
+        assert!(out
+            .stderr
+            .contains("if you meant to update rustup itself, use `rustup self update`"))
+    }
+}
+
+#[tokio::test]
+async fn uninstall_self_smart_guess() {
+    let cx = CliTestContext::new(Scenario::SimpleV2).await;
+    let out = cx.config.run("rustup", &["uninstall", "self"], &[]).await;
+    let no_toolchain_installed = out.stdout.contains("no toolchain installed");
+    if out.ok && no_toolchain_installed {
+        assert!(out
+            .stdout
+            .contains("if you meant to uninstall rustup itself, use `rustup self uninstall`"))
+    }
+}