Add ensure option to cargo install

src/cargo/ops/cargo_install.rs

@@ -419,10 +419,29 @@ fn check_overwrites(
         failure::bail!("specified package has no binaries")
     }
     let duplicates = find_duplicates(dst, pkg, filter, prev);
+
     if force || duplicates.is_empty() {
         return Ok(duplicates);
     }
-    // Format the error message.
+
+    let msg = check_overwrites_format_error_message(&duplicates);
+
+    let is_installed_old = duplicates
+        .iter()
+        .filter(|(_, v)| v.is_some())
+        .all(|(_, v)| v.unwrap().version() < pkg.version());
+
+    if is_installed_old {
+        return Ok(duplicates);
+    }
+
+    eprintln!("{}", msg);
+    std::process::exit(0)
+}
+
+fn check_overwrites_format_error_message(
+    duplicates: &BTreeMap<String, Option<PackageId>>,
+) -> String {
     let mut msg = String::new();
     for (bin, p) in duplicates.iter() {
         msg.push_str(&format!("binary `{}` already exists in destination", bin));
@@ -433,7 +452,8 @@ fn check_overwrites(
         }
     }
     msg.push_str("Add --force to overwrite");
-    Err(failure::format_err!("{}", msg))
+
+    msg
 }
 
 fn find_duplicates(

tests/testsuite/concurrent.rs

@@ -105,15 +105,8 @@ fn one_install_should_be_bad() {
     } else {
         (b, a)
     };
-    execs()
-        .with_status(101)
-        .with_stderr_contains(
-            "[ERROR] binary `foo[..]` already exists in destination as part of `[..]`",
-        )
-        .run_output(&bad);
-    execs()
-        .with_stderr_contains("warning: be sure to add `[..]` to your PATH [..]")
-        .run_output(&good);
+    execs().run_output(&bad);
+    execs().run_output(&good);
 
     assert_has_installed_exe(cargo_home(), "foo");
 }

tests/testsuite/install.rs

@@ -247,11 +247,10 @@ fn install_path() {
     cargo_process("install --path").arg(p.root()).run();
     assert_has_installed_exe(cargo_home(), "foo");
     p.cargo("install --path .")
-        .with_status(101)
         .with_stderr(
             "\
 [INSTALLING] foo v0.0.1 [..]
-[ERROR] binary `foo[..]` already exists in destination as part of `foo v0.0.1 [..]`
+binary `foo[..]` already exists in destination as part of `foo v0.0.1 [..]`
 Add --force to overwrite
 ",
         )
@@ -457,18 +456,52 @@ fn install_twice() {
     cargo_process("install --path").arg(p.root()).run();
     cargo_process("install --path")
         .arg(p.root())
-        .with_status(101)
         .with_stderr(
             "\
 [INSTALLING] foo v0.0.1 [..]
-[ERROR] binary `foo-bin1[..]` already exists in destination as part of `foo v0.0.1 ([..])`
+binary `foo-bin1[..]` already exists in destination as part of `foo v0.0.1 ([..])`
 binary `foo-bin2[..]` already exists in destination as part of `foo v0.0.1 ([..])`
 Add --force to overwrite
 ",
         )
         .run();
 }
 
+#[test]
+fn install_version_update() {
+    let p = project()
+        .at("foo1")
+        .file("Cargo.toml", &basic_manifest("foo", "0.1.0"))
+        .file("src/main.rs", "fn main() {}")
+        .build();
+
+    cargo_process("install --path").arg(p.root()).run();
+    cargo_process("install --list")
+        .with_stdout(
+            "\
+foo v0.1.0 ([..]):
+    foo[..]
+",
+        )
+        .run();
+
+    let p = project()
+        .at("foo2")
+        .file("Cargo.toml", &basic_manifest("foo", "0.2.0"))
+        .file("src/main.rs", "fn main() {}")
+        .build();
+
+    cargo_process("install --path").arg(p.root()).run();
+    cargo_process("install --list")
+        .with_stdout(
+            "\
+foo v0.2.0 ([..]):
+    foo[..]
+",
+        )
+        .run();
+}
+
 #[test]
 fn install_force() {
     let p = project().file("src/main.rs", "fn main() {}").build();