Don't install when multirust metadata exists. Fixes #424

src/rustup-cli/self_update.rs

@@ -293,6 +293,10 @@ fn do_pre_install_sanity_checks() -> Result<()> {
         = PathBuf::from("/usr/local/lib/rustlib/manifest-rustc");
     let uninstaller_path
         = PathBuf::from("/usr/local/lib/rustlib/uninstall.sh");
+    let multirust_meta_path
+        = env::home_dir().map(|d| d.join(".multirust"));
+    let multirust_version_path
+        = multirust_meta_path.as_ref().map(|p| p.join("version"));
     let rustup_sh_path
         = env::home_dir().map(|d| d.join(".rustup"));
     let rustup_sh_version_path = rustup_sh_path.as_ref().map(|p| p.join("rustup-version"));
@@ -303,12 +307,39 @@ fn do_pre_install_sanity_checks() -> Result<()> {
         rustc_manifest_path.exists() && uninstaller_path.exists();
     let rustup_sh_exists =
         rustup_sh_version_path.map(|p| p.exists()) == Some(true);
+    let old_multirust_meta_exists = if let Some(ref multirust_version_path) = multirust_version_path {
+        multirust_version_path.exists() && {
+            let version = utils::read_file("old-multirust", &multirust_version_path);
+            let version = version.unwrap_or(String::new());
+            let version = version.parse().unwrap_or(0);
+            let cutoff_version = 12; // First rustup version
+
+            version < cutoff_version
+        }
+    } else {
+        false
+    };
 
-    if multirust_exists {
-        warn!("it looks like you have an existing installation of multirust");
-        warn!("rustup cannot be installed alongside multirust. Please uninstall first");
-        warn!("run `{}` as root to uninstall multirust", uninstaller_path.display());
-        return Err("cannot install while multirust is installed".into());
+    match (multirust_exists, old_multirust_meta_exists) {
+        (true, false) => {
+            warn!("it looks like you have an existing installation of multirust");
+            warn!("rustup cannot be installed alongside multirust");
+            warn!("run `{}` as root to uninstall multirust before installing rustup", uninstaller_path.display());
+            return Err("cannot install while multirust is installed".into());
+        }
+        (false, true) => {
+            warn!("it looks like you have existing multirust metadata");
+            warn!("rustup cannot be installed alongside multirust");
+            warn!("delete `{}` before installing rustup", multirust_version_path.expect("").display());
+            return Err("cannot install while multirust is installed".into());
+        }
+        (true, true) => {
+            warn!("it looks like you have an existing installation of multirust");
+            warn!("rustup cannot be installed alongside multirust");
+            warn!("run `{}` as root and delete `{}` before installing rustup", uninstaller_path.display(), multirust_version_path.expect("").display());
+            return Err("cannot install while multirust is installed".into());
+        }
+        (false, false) => ()
     }
 
     if rustc_exists {

tests/cli-self-update.rs

@@ -1077,3 +1077,15 @@ fn install_but_rustup_sh_is_installed() {
                    "cannot install while rustup.sh is installed");
     });
 }
+
+#[test]
+fn install_but_multirust_metadata() {
+    setup(&|config| {
+        let multirust_dir = config.homedir.join(".multirust");
+        fs::create_dir_all(&multirust_dir).unwrap();
+        let version_file = multirust_dir.join("version");
+        raw::write_file(&version_file, "2").unwrap();
+        expect_err(config, &["rustup-init", "-y"],
+                   "cannot install while multirust is installed");
+    });
+}