Allow rustup to handle unavailable packages

Before this, if a package was unavailable (like nightly is at the moment),
it would error out with a message like "error: missing key: 'url'" because
at the moment a few of the rust-analysis packages didn't build. This resulted
in the `channel-rust-nightly.toml` to be created with blocks like this:

```toml
[pkg.rust-analysis.target.aarch64-apple-ios]
available = false

[pkg.rust-analysis.target.aarch64-linux-android]
available = false

[pkg.rust-analysis.target.aarch64-unknown-fuchsia]
available = false

[pkg.rust-analysis.target.aarch64-unknown-linux-gnu]
available = true
hash = "be50ffa6f94770929b53bae553977cb6d78b03506f033d14a7251c7b0cdb9035"
url = "https://static.rust-lang.org/dist/2017-04-13/rust-analysis-nightly-aarch64-unknown-linux-gnu.tar.gz"
```

rustup assumed that there'd always be a `hash` and `url`, which is not
the case when packages are unavaible. This patch then just updates
rustup to handle their absence.

src/rustup-dist/src/manifest.rs

@@ -41,13 +41,17 @@ pub enum PackageTargets {
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct TargetedPackage {
-    pub available: bool,
+    pub bins: Option<PackageBins>,
+    pub components: Vec<Component>,
+    pub extensions: Vec<Component>,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct PackageBins {
     pub url: String,
     pub hash: String,
     pub xz_url: Option<String>,
     pub xz_hash: Option<String>,
-    pub components: Vec<Component>,
-    pub extensions: Vec<Component>,
 }
 
 #[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
@@ -232,17 +236,27 @@ impl TargetedPackage {
     pub fn from_toml(mut table: toml::Table, path: &str) -> Result<Self> {
         let components = try!(get_array(&mut table, "components", path));
         let extensions = try!(get_array(&mut table, "extensions", path));
-        Ok(TargetedPackage {
-            available: try!(get_bool(&mut table, "available", path)),
-            url: try!(get_string(&mut table, "url", path)),
-            hash: try!(get_string(&mut table, "hash", path)),
-            xz_url: get_string(&mut table, "xz_url", path).ok(),
-            xz_hash: get_string(&mut table, "xz_hash", path).ok(),
-            components: try!(Self::toml_to_components(components,
-                                                      &format!("{}{}.", path, "components"))),
-            extensions: try!(Self::toml_to_components(extensions,
-                                                      &format!("{}{}.", path, "extensions"))),
-        })
+
+        if try!(get_bool(&mut table, "available", path)) {
+            Ok(TargetedPackage {
+                bins: Some(PackageBins {
+                    url: try!(get_string(&mut table, "url", path)),
+                    hash: try!(get_string(&mut table, "hash", path)),
+                    xz_url: get_string(&mut table, "xz_url", path).ok(),
+                    xz_hash: get_string(&mut table, "xz_hash", path).ok(),
+                }),
+                components: try!(Self::toml_to_components(components,
+                                                          &format!("{}{}.", path, "components"))),
+                extensions: try!(Self::toml_to_components(extensions,
+                                                          &format!("{}{}.", path, "extensions"))),
+            })
+        } else {
+            Ok(TargetedPackage {
+                bins: None,
+                components: vec![],
+                extensions: vec![],
+            })
+        }
     }
     pub fn to_toml(self) -> toml::Table {
         let extensions = Self::components_to_toml(self.extensions);
@@ -254,12 +268,24 @@ impl TargetedPackage {
         if !components.is_empty() {
             result.insert("components".to_owned(), toml::Value::Array(components));
         }
-        result.insert("hash".to_owned(), toml::Value::String(self.hash));
-        result.insert("url".to_owned(), toml::Value::String(self.url));
-        result.insert("available".to_owned(), toml::Value::Boolean(self.available));
+        if let Some(bins) = self.bins.clone() {
+            result.insert("hash".to_owned(), toml::Value::String(bins.hash));
+            result.insert("url".to_owned(), toml::Value::String(bins.url));
+            if let (Some(xz_hash), Some(xz_url)) = (bins.xz_hash, bins.xz_url) {
+                result.insert("xz_hash".to_owned(), toml::Value::String(xz_hash));
+                result.insert("xz_url".to_owned(), toml::Value::String(xz_url));
+            }
+            result.insert("available".to_owned(), toml::Value::Boolean(true));
+        } else {
+            result.insert("available".to_owned(), toml::Value::Boolean(false));
+        }
         result
     }
 
+    pub fn available(&self) -> bool {
+        self.bins.is_some()
+    }
+
     fn toml_to_components(arr: toml::Array, path: &str) -> Result<Vec<Component>> {
         let mut result = Vec::new();
 

src/rustup-dist/src/manifestation.rs

@@ -112,7 +112,7 @@ impl Manifestation {
             use manifest::*;
             let pkg: Option<&Package> = new_manifest.get_package(&c.pkg).ok();
             let target_pkg: Option<&TargetedPackage> = pkg.and_then(|p| p.get_target(c.target.as_ref()).ok());
-            target_pkg.map(|tp| tp.available) != Some(true)
+            target_pkg.map(|tp| tp.available()) != Some(true)
         }).cloned().collect();
 
         if !unavailable_components.is_empty() {
@@ -124,12 +124,14 @@ impl Manifestation {
         for component in components_to_install {
             let package = try!(new_manifest.get_package(&component.pkg));
             let target_package = try!(package.get_target(component.target.as_ref()));
+
+            let bins = target_package.bins.as_ref().expect("components available");
             let c_u_h =
-                if let (Some(url), Some(hash)) = (target_package.xz_url.clone(),
-                                                 target_package.xz_hash.clone()) {
+                if let (Some(url), Some(hash)) = (bins.xz_url.clone(),
+                                                  bins.xz_hash.clone()) {
                     (component, Format::Xz, url, hash)
                 } else {
-                    (component, Format::Gz, target_package.url.clone(), target_package.hash.clone())
+                    (component, Format::Gz, bins.url.clone(), bins.hash.clone())
                 };
             components_urls_and_hashes.push(c_u_h);
         }

src/rustup/toolchain.rs

@@ -491,7 +491,7 @@ impl<'a> Toolchain<'a> {
                     component: component.clone(),
                     required: true,
                     installed: installed,
-                    available: component_target_pkg.available,
+                    available: component_target_pkg.available(),
                 });
             }
 
@@ -510,7 +510,7 @@ impl<'a> Toolchain<'a> {
                     component: extension.clone(),
                     required: false,
                     installed: installed,
-                    available: extension_target_pkg.available,
+                    available: extension_target_pkg.available(),
                 });
             }
 

tests/cli-v2.rs

@@ -668,7 +668,7 @@ fn make_component_unavailable(config: &Config, name: &str, target: &TargetTriple
     {
         let mut std_pkg = manifest.packages.get_mut(name).unwrap();
         let mut target_pkg = std_pkg.targets.get_mut(target).unwrap();
-        target_pkg.available = false;
+        target_pkg.bins = None;
     }
     let ref manifest_str = manifest.stringify();
     rustup_utils::raw::write_file(manifest_path, manifest_str).unwrap();