rustup check: adopt no-self-update logic

The 'self update' subcommand checks whether self updates have been
disabled, but 'check' did not, meaning the check output could include
updates you're powerless to accept.

This adds the logic from self update to check, no longer showing updates
that can't be applied by rustup, along with its --no-self-update flag,
in case you *are* able to update rustup but don't want to check it for
updates at the moment.

Author: tjkirch

src/cli/rustup_mode.rs

@@ -177,7 +177,10 @@ enum RustupSubcmd {
     },
 
     /// Check for updates to Rust toolchains and rustup
-    Check,
+    Check {
+        #[command(flatten)]
+        opts: CheckOpts,
+    },
 
     /// Modify a toolchain's supported targets
     Target {
@@ -338,6 +341,13 @@ enum ToolchainSubcmd {
     },
 }
 
+#[derive(Debug, Default, Args)]
+struct CheckOpts {
+    /// Don't check for self update when running the `rustup check` command
+    #[arg(long)]
+    no_self_update: bool,
+}
+
 #[derive(Debug, Default, Args)]
 struct UpdateOpts {
     #[arg(
@@ -650,7 +660,7 @@ pub async fn main(
             }
             ToolchainSubcmd::Uninstall { opts } => toolchain_remove(cfg, opts).await,
         },
-        RustupSubcmd::Check => check_updates(cfg).await,
+        RustupSubcmd::Check { opts } => check_updates(cfg, opts).await,
         RustupSubcmd::Default {
             toolchain,
             force_non_host,
@@ -779,7 +789,7 @@ async fn default_(
     Ok(utils::ExitCode(0))
 }
 
-async fn check_updates(cfg: &Cfg<'_>) -> Result<utils::ExitCode> {
+async fn check_updates(cfg: &Cfg<'_>, opts: CheckOpts) -> Result<utils::ExitCode> {
     let mut t = cfg.process.stdout().terminal(cfg.process);
     let channels = cfg.list_channels()?;
 
@@ -815,7 +825,18 @@ async fn check_updates(cfg: &Cfg<'_>) -> Result<utils::ExitCode> {
         }
     }
 
-    check_rustup_update(cfg.process).await?;
+    let self_update_mode = cfg.get_self_update_mode()?;
+    // Priority: no-self-update feature > self_update_mode > no-self-update args.
+    // Check for update only if rustup does **not** have the no-self-update feature,
+    // and auto-self-update is configured to **enable**
+    // and has **no** no-self-update parameter.
+    let self_update = !self_update::NEVER_SELF_UPDATE
+        && self_update_mode == SelfUpdateMode::Enable
+        && !opts.no_self_update;
+
+    if self_update {
+        check_rustup_update(cfg.process).await?;
+    }
 
     Ok(utils::ExitCode(0))
 }

tests/suite/cli-ui/rustup/rustup_check_cmd_help_flag_stdout.toml

@@ -4,9 +4,10 @@ stdout = """
 ...
 Check for updates to Rust toolchains and rustup
 
-Usage: rustup[EXE] check
+Usage: rustup[EXE] check [OPTIONS]
 
 Options:
-  -h, --help  Print help
+      --no-self-update  Don't check for self update when running the `rustup check` command
+  -h, --help            Print help
 """
 stderr = ""

tests/suite/cli_exact.rs

@@ -208,6 +208,11 @@ async fn check_updates_self() {
     let _dist_guard = cx.with_update_server(test_version);
     let current_version = env!("CARGO_PKG_VERSION");
 
+    // We are checking an update to rustup itself in this test.
+    cx.config
+        .run("rustup", ["set", "auto-self-update", "enable"], &[])
+        .await;
+
     cx.config
         .expect_stdout_ok(
             &["rustup", "check"],
@@ -224,6 +229,12 @@ async fn check_updates_self_no_change() {
     let current_version = env!("CARGO_PKG_VERSION");
     let mut cx = CliTestContext::new(Scenario::SimpleV2).await;
     let _dist_guard = cx.with_update_server(current_version);
+
+    // We are checking an update to rustup itself in this test.
+    cx.config
+        .run("rustup", ["set", "auto-self-update", "enable"], &[])
+        .await;
+
     cx.config
         .expect_stdout_ok(
             &["rustup", "check"],