warn toolchain

src/install.rs

@@ -70,6 +70,22 @@ impl<'a> InstallMethod<'a> {
             ));
         }
 
+        match self {
+            InstallMethod::Dist { desc, .. } => {
+                let host_arch = dist::TargetTriple::from_host_or_build();
+                let target_triple = desc.target.clone();
+                if host_arch.ne(&target_triple) {
+                    (toolchain.cfg().notify_handler)(RootNotification::UnmatchToolchain(
+                        &toolchain.name(),
+                    ));
+                    (toolchain.cfg().notify_handler)(RootNotification::SuggestTarget(
+                        &target_triple.to_string(),
+                    ));
+                }
+            }
+            _ => (),
+        };
+
         let status = match (updated, previous_version) {
             (true, None) => UpdateStatus::Installed,
             (true, Some(v)) => UpdateStatus::Updated(v),

src/notifications.rs

@@ -33,6 +33,8 @@ pub enum Notification<'a> {
     UpgradeRemovesToolchains,
     MissingFileDuringSelfUninstall(PathBuf),
     PlainVerboseMessage(&'a str),
+    UnmatchToolchain(&'a str),
+    SuggestTarget(&'a str),
 }
 
 impl<'a> From<crate::dist::Notification<'a>> for Notification<'a> {
@@ -77,7 +79,10 @@ impl<'a> Notification<'a> {
             | UpgradingMetadata(_, _)
             | MetadataUpgradeNotNeeded(_) => NotificationLevel::Info,
             NonFatalError(_) => NotificationLevel::Error,
-            UpgradeRemovesToolchains | MissingFileDuringSelfUninstall(_) => NotificationLevel::Warn,
+            UpgradeRemovesToolchains
+            | MissingFileDuringSelfUninstall(_)
+            | UnmatchToolchain(_)
+            | SuggestTarget(_) => NotificationLevel::Warn,
         }
     }
 }
@@ -130,6 +135,8 @@ impl<'a> Display for Notification<'a> {
                 p.display()
             ),
             PlainVerboseMessage(r) => write!(f, "{}", r),
+            UnmatchToolchain(name) => write!(f, "toolchain '{}' may not be able to run on this system.", name),
+            SuggestTarget(t)=>write!(f,"If you meant to build software to target that platform, perhaps try `rustup target add {}` instead?",t)
         }
     }
 }

tests/cli-rustup.rs

@@ -1940,3 +1940,25 @@ fn check_host_goes_away() {
         );
     })
 }
+
+#[test]
+fn warn_on_unmatch_build() {
+    clitools::setup(Scenario::MultiHost, &|config| {
+        let arch = clitools::MULTI_ARCH1;
+        expect_stderr_ok(
+            config,
+            &[
+                "rustup",
+                "toolchain",
+                "install",
+                &format!("nightly-{}", arch),
+                "--no-self-update",
+            ],
+            &format!(
+                r"warning: toolchain 'nightly-{0}' may not be able to run on this system.
+warning: If you meant to build software to target that platform, perhaps try `rustup target add {0}` instead?",
+                arch,
+            ),
+        );
+    });
+}