rustup check: set exit status based on available updates

This helps with interfaces above rustup, for example prompting a user to
update, but only if updates are actually available.

If any updates are available, exits 0, otherwise exits 1.  This allows
"natural" shell commands like 'if rustup check; then <update>'.  It also
mirrors existing exit codes for update, where rustup exits 1 if updates
are not permitted by the distribution or because of errors.

Author: tjkirch

src/cli/rustup_mode.rs

@@ -19,7 +19,7 @@ use crate::{
         common::{self, PackageUpdate, update_console_filter},
         errors::CLIError,
         help::*,
-        self_update::{self, SelfUpdateMode, check_rustup_update},
+        self_update::{self, RustupUpdateAvailable, SelfUpdateMode, check_rustup_update},
         topical_doc,
     },
     command,
@@ -790,6 +790,8 @@ async fn default_(
 }
 
 async fn check_updates(cfg: &Cfg<'_>, opts: CheckOpts) -> Result<utils::ExitCode> {
+    let mut update_available = false;
+
     let mut t = cfg.process.stdout().terminal(cfg.process);
     let channels = cfg.list_channels()?;
 
@@ -811,12 +813,14 @@ async fn check_updates(cfg: &Cfg<'_>, opts: CheckOpts) -> Result<utils::ExitCode
                 writeln!(t.lock(), " : {cv}")?;
             }
             (Some(cv), Some(dv)) => {
+                update_available = true;
                 let _ = t.fg(terminalsource::Color::Yellow);
                 write!(t.lock(), "Update available")?;
                 let _ = t.reset();
                 writeln!(t.lock(), " : {cv} -> {dv}")?;
             }
             (None, Some(dv)) => {
+                update_available = true;
                 let _ = t.fg(terminalsource::Color::Yellow);
                 write!(t.lock(), "Update available")?;
                 let _ = t.reset();
@@ -834,11 +838,17 @@ async fn check_updates(cfg: &Cfg<'_>, opts: CheckOpts) -> Result<utils::ExitCode
         && self_update_mode == SelfUpdateMode::Enable
         && !opts.no_self_update;
 
-    if self_update {
-        check_rustup_update(cfg.process).await?;
+    if self_update
+        && matches!(
+            check_rustup_update(cfg.process).await?,
+            RustupUpdateAvailable::True
+        )
+    {
+        update_available = true;
     }
 
-    Ok(utils::ExitCode(0))
+    let exit_status = if update_available { 0 } else { 1 };
+    Ok(utils::ExitCode(exit_status))
 }
 
 async fn update(

src/cli/self_update.rs

@@ -1250,7 +1250,15 @@ impl fmt::Display for SchemaVersion {
     }
 }
 
-pub(crate) async fn check_rustup_update(process: &Process) -> Result<()> {
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub(crate) enum RustupUpdateAvailable {
+    True,
+    False,
+}
+
+pub(crate) async fn check_rustup_update(process: &Process) -> Result<RustupUpdateAvailable> {
+    let mut update_available = RustupUpdateAvailable::False;
+
     let mut t = process.stdout().terminal(process);
     // Get current rustup version
     let current_version = env!("CARGO_PKG_VERSION");
@@ -1262,6 +1270,8 @@ pub(crate) async fn check_rustup_update(process: &Process) -> Result<()> {
     write!(t.lock(), "rustup - ")?;
 
     if current_version != available_version {
+        update_available = RustupUpdateAvailable::True;
+
         let _ = t.fg(terminalsource::Color::Yellow);
         write!(t.lock(), "Update available")?;
         let _ = t.reset();
@@ -1273,7 +1283,7 @@ pub(crate) async fn check_rustup_update(process: &Process) -> Result<()> {
         writeln!(t.lock(), " : {current_version}")?;
     }
 
-    Ok(())
+    Ok(update_available)
 }
 
 #[tracing::instrument(level = "trace")]

tests/suite/cli_exact.rs

@@ -166,16 +166,15 @@ async fn check_updates_none() {
         .expect_ok(&["rustup", "toolchain", "add", "stable", "beta", "nightly"])
         .await;
     cx.config
-        .expect_stdout_ok(
-            &["rustup", "check"],
-            for_host!(
-                r"stable-{0} - Up to date : 1.1.0 (hash-stable-1.1.0)
-beta-{0} - Up to date : 1.2.0 (hash-beta-1.2.0)
-nightly-{0} - Up to date : 1.3.0 (hash-nightly-2)
-"
-            ),
-        )
-        .await;
+        .expect(["rustup", "check"])
+        .await
+        .is_err()
+        .with_stdout(snapbox::str![[r#"
+stable-[HOST_TRIPLE] - Up to date : 1.1.0 (hash-stable-1.1.0)
+beta-[HOST_TRIPLE] - Up to date : 1.2.0 (hash-beta-1.2.0)
+nightly-[HOST_TRIPLE] - Up to date : 1.3.0 (hash-nightly-2)
+
+"#]]);
 }
 
 #[tokio::test]
@@ -236,14 +235,13 @@ async fn check_updates_self_no_change() {
         .await;
 
     cx.config
-        .expect_stdout_ok(
-            &["rustup", "check"],
-            &format!(
-                r"rustup - Up to date : {current_version}
+        .expect(["rustup", "check"])
+        .await
+        .is_err()
+        .with_stdout(format!(
+            r"rustup - Up to date : {current_version}
 "
-            ),
-        )
-        .await;
+        ));
 }
 
 #[tokio::test]
@@ -256,16 +254,15 @@ async fn check_updates_with_update() {
             .expect_ok(&["rustup", "toolchain", "add", "stable", "beta", "nightly"])
             .await;
         cx.config
-            .expect_stdout_ok(
-                &["rustup", "check"],
-                for_host!(
-                    r"stable-{0} - Up to date : 1.0.0 (hash-stable-1.0.0)
-beta-{0} - Up to date : 1.1.0 (hash-beta-1.1.0)
-nightly-{0} - Up to date : 1.2.0 (hash-nightly-1)
-"
-                ),
-            )
-            .await;
+            .expect(["rustup", "check"])
+            .await
+            .is_err()
+            .with_stdout(snapbox::str![[r#"
+stable-[HOST_TRIPLE] - Up to date : 1.0.0 (hash-stable-1.0.0)
+beta-[HOST_TRIPLE] - Up to date : 1.1.0 (hash-beta-1.1.0)
+nightly-[HOST_TRIPLE] - Up to date : 1.2.0 (hash-nightly-1)
+
+"#]]);
     }
 
     let mut cx = cx.with_dist_dir(Scenario::SimpleV2);