Don't require the serde feature of url

Ends up meaning that in full crate compiles that `url` doesn't wait for
`serde` to finish, which in turn enables crates like `git2` to start
sooner!

Author: alexcrichton

Cargo.toml

@@ -61,7 +61,7 @@ tar = { version = "0.4.18", default-features = false }
 tempfile = "3.0"
 termcolor = "1.0"
 toml = "0.5.3"
-url = { version = "2.0", features = ['serde'] }
+url = "2.0"
 walkdir = "2.2"
 clap = "2.31.2"
 unicode-width = "0.1.5"

src/cargo/core/dependency.rs

@@ -7,7 +7,6 @@ use semver::ReqParseError;
 use semver::VersionReq;
 use serde::ser;
 use serde::Serialize;
-use url::Url;
 
 use crate::core::interning::InternedString;
 use crate::core::{PackageId, SourceId, Summary};
@@ -69,14 +68,15 @@ struct SerializedDependency<'a> {
     target: Option<&'a Platform>,
     /// The registry URL this dependency is from.
     /// If None, then it comes from the default registry (crates.io).
-    registry: Option<Url>,
+    registry: Option<&'a str>,
 }
 
 impl ser::Serialize for Dependency {
     fn serialize<S>(&self, s: S) -> Result<S::Ok, S::Error>
     where
         S: ser::Serializer,
     {
+        let registry_id = self.registry_id();
         SerializedDependency {
             name: &*self.package_name(),
             source: self.source_id(),
@@ -87,7 +87,7 @@ impl ser::Serialize for Dependency {
             features: self.features(),
             target: self.platform(),
             rename: self.explicit_name_in_toml().map(|s| s.as_str()),
-            registry: self.registry_id().map(|sid| sid.url().clone()),
+            registry: registry_id.as_ref().map(|sid| sid.url().as_str()),
         }
         .serialize(s)
     }