fix!(config): re-enable implicit toolchain installation in Cfg::local_toolchain() with optional opt-out

src/config.rs

@@ -784,16 +784,23 @@ impl<'a> Cfg<'a> {
     }
 
     async fn local_toolchain(&self, name: Option<LocalToolchainName>) -> Result<Toolchain<'_>> {
-        let toolchain = match name {
-            Some(tc) => tc,
+        match name {
+            Some(tc) => {
+                let install_if_missing = self
+                    .process
+                    .var("RUSTUP_AUTO_INSTALL")
+                    .map_or(true, |it| it != "0");
+                Toolchain::from_local(tc, install_if_missing, self).await
+            }
             None => {
-                self.find_active_toolchain(None)
+                let tc = self
+                    .find_active_toolchain(None)
                     .await?
                     .ok_or_else(|| no_toolchain_error(self.process))?
-                    .0
+                    .0;
+                Ok(Toolchain::new(self, tc)?)
             }
-        };
-        Ok(Toolchain::new(self, toolchain)?)
+        }
     }
 
     #[tracing::instrument(level = "trace", skip_all)]

src/test/clitools.rs

@@ -147,7 +147,12 @@ impl Config {
 
     /// Expect an err status and a string in stderr
     pub async fn expect_err(&self, args: &[&str], expected: &str) {
-        let out = self.run(args[0], &args[1..], &[]).await;
+        self.expect_err_env(args, &[], expected).await
+    }
+
+    /// Expect an err status and a string in stderr, with extra environment variables
+    pub async fn expect_err_env(&self, args: &[&str], env: &[(&str, &str)], expected: &str) {
+        let out = self.run(args[0], &args[1..], env).await;
         if out.ok || !out.stderr.contains(expected) {
             print_command(args, &out);
             println!("expected.ok: false");

tests/suite/cli_exact.rs

@@ -687,9 +687,9 @@ info: installing component 'rust-std' for '{0}'
 async fn show_suggestion_for_missing_toolchain() {
     let cx = CliTestContext::new(Scenario::SimpleV2).await;
     cx.config
-        .expect_err_ex(
+        .expect_err_env(
             &["cargo", "+nightly", "fmt"],
-            r"",
+            &[("RUSTUP_AUTO_INSTALL", "0")],
             for_host!(
                 r"error: toolchain 'nightly-{0}' is not installed
 help: run `rustup toolchain install nightly-{0}` to install it

tests/suite/cli_misc.rs

@@ -1073,24 +1073,17 @@ async fn which_asking_uninstalled_toolchain() {
     cx.config
         .expect_ok(&["rustup", "default", "custom-1"])
         .await;
-    #[cfg(windows)]
     cx.config
         .expect_stdout_ok(
             &["rustup", "which", "rustc"],
-            "\\toolchains\\custom-1\\bin\\rustc",
+            &["", "toolchains", "custom-1", "bin", "rustc"].join(std::path::MAIN_SEPARATOR_STR),
         )
         .await;
-    #[cfg(not(windows))]
     cx.config
         .expect_stdout_ok(
-            &["rustup", "which", "rustc"],
-            "/toolchains/custom-1/bin/rustc",
-        )
-        .await;
-    cx.config
-        .expect_err(
             &["rustup", "which", "--toolchain=nightly", "rustc"],
-            for_host!("toolchain 'nightly-{}' is not installed"),
+            &["", "toolchains", for_host!("nightly-{0}"), "bin", "rustc"]
+                .join(std::path::MAIN_SEPARATOR_STR),
         )
         .await;
 }

tests/suite/cli_v2.rs

@@ -354,11 +354,19 @@ async fn file_override_toolchain_err_handling() {
 async fn plus_override_toolchain_err_handling() {
     let cx = CliTestContext::new(Scenario::SimpleV2).await;
     cx.config
-        .expect_err(
-            &["rustc", "+beta"],
+        .expect_err_env(
+            &["rustc", "+beta", "--version"],
+            &[("RUSTUP_AUTO_INSTALL", "0")],
             for_host!("toolchain 'beta-{0}' is not installed"),
         )
         .await;
+    cx.config
+        .expect_ok_contains(
+            &["rustc", "+beta", "--version"],
+            "1.2.0 (hash-beta-1.2.0)",
+            "",
+        )
+        .await;
 }
 
 #[tokio::test]
@@ -776,8 +784,9 @@ async fn upgrade_v2_to_v1() {
 async fn list_targets_no_toolchain() {
     let cx = CliTestContext::new(Scenario::SimpleV2).await;
     cx.config
-        .expect_err(
+        .expect_err_env(
             &["rustup", "target", "list", "--toolchain=nightly"],
+            &[("RUSTUP_AUTO_INSTALL", "0")],
             for_host!("toolchain 'nightly-{0}' is not installed"),
         )
         .await;
@@ -962,18 +971,20 @@ async fn remove_target_by_component_remove() {
 async fn add_target_no_toolchain() {
     let cx = CliTestContext::new(Scenario::SimpleV2).await;
     cx.config
-        .expect_err(
+        .expect_err_env(
             &[
                 "rustup",
                 "target",
                 "add",
                 CROSS_ARCH1,
                 "--toolchain=nightly",
             ],
+            &[("RUSTUP_AUTO_INSTALL", "0")],
             for_host!("toolchain 'nightly-{0}' is not installed"),
         )
         .await;
 }
+
 #[tokio::test]
 async fn add_target_bogus() {
     let mut cx = CliTestContext::new(Scenario::SimpleV2).await;
@@ -1120,14 +1131,15 @@ async fn remove_target_not_installed() {
 async fn remove_target_no_toolchain() {
     let cx = CliTestContext::new(Scenario::SimpleV2).await;
     cx.config
-        .expect_err(
+        .expect_err_env(
             &[
                 "rustup",
                 "target",
                 "remove",
                 CROSS_ARCH1,
                 "--toolchain=nightly",
             ],
+            &[("RUSTUP_AUTO_INSTALL", "0")],
             for_host!("toolchain 'nightly-{0}' is not installed"),
         )
         .await;