Updating based on review comments.

src/bin/login.rs

@@ -55,8 +55,8 @@ pub fn execute(options: Options, config: &mut Config) -> CliResult {
         Some(token) => token,
         None => {
             let host = match options.flag_registry {
-                Some(ref registry) => {
-                    config.get_registry_index(registry)?
+                Some(ref _registry) => {
+                    return Err(CargoError::from("token must be provided when --registry is provided.").into());
                 }
                 None => {
                     let src = SourceId::crates_io(config)?;

src/cargo/core/source/source_id.rs

@@ -183,8 +183,7 @@ impl SourceId {
     }
 
     pub fn alt_registry(config: &Config, key: &str) -> CargoResult<SourceId> {
-        let index = config.get_registry_index(key)?;
-        let url = index.to_url()?;
+        let url = config.get_registry_index(key)?;
         Ok(SourceId {
             inner: Arc::new(SourceIdInner {
                 kind: Kind::Registry,

src/cargo/ops/registry.rs

@@ -196,7 +196,7 @@ pub fn registry_configuration(config: &Config,
 
     let (index, token) = match registry {
         Some(registry) => {
-            let index = Some(config.get_registry_index(&registry)?);
+            let index = Some(config.get_registry_index(&registry)?.to_string());
             let table = config.get_table(&format!("registry.{}", registry))?.map(|t| t.val);
             let token = table.and_then(|table| {
                 match table.get("token".into()) {

src/cargo/util/config.rs

@@ -20,6 +20,8 @@ use toml;
 use core::shell::Verbosity;
 use core::{Shell, CliUnstable};
 use ops;
+use url::Url;
+use util::ToUrl;
 use util::Rustc;
 use util::errors::{CargoResult, CargoResultExt, CargoError, internal};
 use util::paths;
@@ -546,9 +548,9 @@ impl Config {
     }
 
     /// Gets the index for a registry.
-    pub fn get_registry_index(&self, registry: &str) -> CargoResult<String> {
+    pub fn get_registry_index(&self, registry: &str) -> CargoResult<Url> {
         Ok(match self.get_string(&format!("registries.{}.index", registry))? {
-            Some(index) => index.val,
+            Some(index) => index.val.to_url()?,
             None => return Err(CargoError::from(format!("No index found for registry: `{}`", registry)).into()),
         })
     }

tests/login.rs

@@ -22,10 +22,10 @@ const CONFIG_FILE: &str = r#"
     token = "api-token"
 
     [registries.test-reg]
-    index = "dummy_index"
+    index = "http://dummy_index/"
 
     [registries.test.reg]
-    index = "dummy_index"
+    index = "http://dummy_index/"
 "#;
 
 fn setup_old_credentials() {