Fix overwriting alternate registry token

When executing `cargo login`, 2nd alternate registry token overwrites
1st alternate registry token.

Fixes #7701.

crates/cargo-test-support/src/registry.rs

@@ -44,6 +44,12 @@ pub fn alt_registry_path() -> PathBuf {
 pub fn alt_registry_url() -> Url {
     Url::from_file_path(alt_registry_path()).ok().unwrap()
 }
+pub fn alt2_registry_path() -> PathBuf {
+    paths::root().join("alternative2-registry")
+}
+pub fn alt2_registry_url() -> Url {
+    Url::from_file_path(alt_registry_path()).ok().unwrap()
+}
 /// Gets the alternative-registry version of `dl_path`.
 pub fn alt_dl_path() -> PathBuf {
     paths::root().join("alt_dl")
@@ -52,6 +58,13 @@ pub fn alt_dl_url() -> String {
     let base = Url::from_file_path(alt_dl_path()).ok().unwrap();
     format!("{}/{{crate}}/{{version}}/{{crate}}-{{version}}.crate", base)
 }
+pub fn alt2_dl_path() -> PathBuf {
+    paths::root().join("alt2_dl")
+}
+pub fn alt2_dl_url() -> String {
+    let base = Url::from_file_path(alt2_dl_path()).ok().unwrap();
+    format!("{}/{{crate}}/{{version}}/{{crate}}-{{version}}.crate", base)
+}
 /// Gets the alternative-registry version of `api_path`.
 pub fn alt_api_path() -> PathBuf {
     paths::root().join("alt_api")
@@ -59,6 +72,12 @@ pub fn alt_api_path() -> PathBuf {
 pub fn alt_api_url() -> Url {
     Url::from_file_path(alt_api_path()).ok().unwrap()
 }
+pub fn alt2_api_path() -> PathBuf {
+    paths::root().join("alt2_api")
+}
+pub fn alt2_api_url() -> Url {
+    Url::from_file_path(alt2_api_path()).ok().unwrap()
+}
 
 /// A builder for creating a new package in a registry.
 ///
@@ -166,9 +185,13 @@ pub fn init() {
 
         [registries.alternative]
         index = '{alt}'
+
+        [registries.alternative2]
+        index = '{alt2}'
     "#,
             reg = registry_url(),
-            alt = alt_registry_url()
+            alt = alt_registry_url(),
+            alt2 = alt2_registry_url()
         )
         .as_bytes()
     ));
@@ -180,6 +203,9 @@ pub fn init() {
 
         [registries.alternative]
         token = "api-token"
+
+        [registries.alternative2]
+        token = "api-token"
     "#
     ));
 
@@ -212,6 +238,21 @@ pub fn init() {
         )
         .build();
     fs::create_dir_all(alt_api_path().join("api/v1/crates")).unwrap();
+
+    // Initialize an alternative2 registry.
+    repo(&alt2_registry_path())
+        .file(
+            "config.json",
+            &format!(
+                r#"
+            {{"dl":"{}","api":"{}"}}
+        "#,
+                alt2_dl_url(),
+                alt2_api_url()
+            ),
+        )
+        .build();
+    fs::create_dir_all(alt2_api_path().join("api/v1/crates")).unwrap();
 }
 
 impl Package {

src/cargo/util/config/mod.rs

@@ -1314,14 +1314,14 @@ pub fn save_credentials(cfg: &Config, token: String, registry: Option<String>) -
             .open_rw(filename, cfg, "credentials' config file")?
     };
 
-    let (key, value) = {
+    let (key, mut value) = {
         let key = "token".to_string();
         let value = ConfigValue::String(token, file.path().to_path_buf());
         let mut map = HashMap::new();
         map.insert(key, value);
         let table = CV::Table(map, file.path().to_path_buf());
 
-        if let Some(registry) = registry {
+        if let Some(registry) = registry.clone() {
             let mut map = HashMap::new();
             map.insert(registry, table);
             (
@@ -1352,6 +1352,12 @@ pub fn save_credentials(cfg: &Config, token: String, registry: Option<String>) -
             .insert("registry".into(), map.into());
     }
 
+    if let Some(_) = registry {
+        if let Some(table) = toml.as_table_mut().unwrap().remove("registries") {
+            let v = CV::from_toml(file.path(), table)?;
+            value.merge(v)?;
+        }
+    }
     toml.as_table_mut().unwrap().insert(key, value.into_toml());
 
     let contents = toml.to_string();

tests/testsuite/login.rs

@@ -12,6 +12,7 @@ use cargo_test_support::{cargo_process, t};
 use toml;
 
 const TOKEN: &str = "test-token";
+const TOKEN2: &str = "test-token2";
 const ORIGINAL_TOKEN: &str = "api-token";
 
 fn setup_new_credentials() {
@@ -185,4 +186,18 @@ fn registry_credentials() {
 
     // Also ensure that we get the new token for the registry
     assert!(check_token(TOKEN, Some(reg)));
+
+    let reg2 = "alternative2";
+    cargo_process("login --registry")
+        .arg(reg2)
+        .arg(TOKEN2)
+        .arg("-Zunstable-options")
+        .masquerade_as_nightly_cargo()
+        .run();
+
+    // Ensure not overwriting 1st alternate registry token with
+    // 2nd alternate registry token (see rust-lang/cargo#7701).
+    assert!(check_token(ORIGINAL_TOKEN, None));
+    assert!(check_token(TOKEN, Some(reg)));
+    assert!(check_token(TOKEN2, Some(reg2)));
 }