Add some comments

Author: tgross35

compiler/rustc_metadata/src/creader.rs

@@ -390,10 +390,12 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         None
     }
 
-    // The `dependency` type is determined by the command line arguments(`--extern`) and
-    // `private_dep`. However, sometimes the directly dependent crate is not specified by
-    // `--extern`, in this case, `private-dep` is none during loading. This is equivalent to the
-    // scenario where the command parameter is set to `public-dependency`
+    /// The `dependency` type is determined by the command line arguments(`--extern`) and
+    /// `private_dep`.
+    ///
+    /// Sometimes the directly dependent crate is not specified by `--extern`, in this case,
+    /// `private-dep` is none during loading. This is equivalent to the scenario where the
+    /// command parameter is set to `public-dependency`
     fn is_private_dep(&self, name: &str, private_dep: Option<bool>) -> bool {
         self.sess.opts.externs.get(name).map_or(private_dep.unwrap_or(false), |e| e.is_private_dep)
             && private_dep.unwrap_or(true)

compiler/rustc_metadata/src/locator.rs

@@ -262,7 +262,7 @@ pub(crate) struct CrateLocator<'a> {
 
 #[derive(Clone)]
 pub(crate) struct CratePaths {
-    name: Symbol,
+    pub(crate) name: Symbol,
     source: CrateSource,
 }
 

compiler/rustc_middle/src/query/mod.rs

@@ -2128,6 +2128,8 @@ rustc_queries! {
         eval_always
         desc { "calculating the stability index for the local crate" }
     }
+    /// All available crates in the graph, including those that should not be user-facing
+    /// (such as private crates).
     query crates(_: ()) -> &'tcx [CrateNum] {
         eval_always
         desc { "fetching all foreign CrateNum instances" }