If the parent dependency is private, treat dependents as private

Currently, marking a dependency private does not automatically make all
its child dependencies private. Resolve this by making its children
private by default as well.

[1]: rust-lang#135501 (comment)

Author: tgross35

compiler/rustc_metadata/src/creader.rs

@@ -456,7 +456,8 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
             &crate_paths
         };
 
-        let cnum_map = self.resolve_crate_deps(dep_root, &crate_root, &metadata, cnum, dep_kind)?;
+        let cnum_map =
+            self.resolve_crate_deps(dep_root, &crate_root, &metadata, cnum, dep_kind, private_dep)?;
 
         let raw_proc_macros = if crate_root.is_proc_macro_crate() {
             let temp_root;
@@ -559,15 +560,16 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         dep_kind: CrateDepKind,
     ) -> Option<CrateNum> {
         self.used_extern_options.insert(name);
-        match self.maybe_resolve_crate(name, dep_kind, None) {
+        match self.maybe_resolve_crate(name, dep_kind, None, false) {
             Ok(cnum) => {
                 self.cstore.set_used_recursively(cnum);
                 Some(cnum)
             }
             Err(err) => {
                 debug!("failed to resolve crate {} {:?}", name, dep_kind);
-                let missing_core =
-                    self.maybe_resolve_crate(sym::core, CrateDepKind::Explicit, None).is_err();
+                let missing_core = self
+                    .maybe_resolve_crate(sym::core, CrateDepKind::Explicit, None, false)
+                    .is_err();
                 err.report(self.sess, span, missing_core);
                 None
             }
@@ -579,6 +581,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         name: Symbol,
         mut dep_kind: CrateDepKind,
         dep_of: Option<(&'b CratePaths, &'b CrateDep)>,
+        parent_is_private: bool,
     ) -> Result<CrateNum, CrateError> {
         info!("resolving crate `{}`", name);
         if !name.as_str().is_ascii() {
@@ -591,7 +594,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         let host_hash = dep.map(|d| d.host_hash).flatten();
         let extra_filename = dep.map(|d| &d.extra_filename[..]);
         let path_kind = if dep.is_some() { PathKind::Dependency } else { PathKind::Crate };
-        let private_dep = dep.map(|d| d.is_private);
+        let private_dep = dep.map(|d| d.is_private || parent_is_private);
 
         let result = if let Some(cnum) = self.existing_match(name, hash, path_kind) {
             (LoadResult::Previous(cnum), None)
@@ -688,6 +691,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         metadata: &MetadataBlob,
         krate: CrateNum,
         dep_kind: CrateDepKind,
+        parent_is_private: bool,
     ) -> Result<CrateNumMap, CrateError> {
         debug!(
             "resolving deps of external crate `{}` with dep root `{}`",
@@ -706,17 +710,23 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         crate_num_map.push(krate);
         for dep in deps {
             info!(
-                "resolving dep `{}`->`{}` hash: `{}` extra filename: `{}`",
+                "resolving dep `{}`->`{}` hash: `{}` extra filename: `{}` private {}",
                 crate_root.name(),
                 dep.name,
                 dep.hash,
-                dep.extra_filename
+                dep.extra_filename,
+                dep.is_private,
             );
             let dep_kind = match dep_kind {
                 CrateDepKind::MacrosOnly => CrateDepKind::MacrosOnly,
                 _ => dep.kind,
             };
-            let cnum = self.maybe_resolve_crate(dep.name, dep_kind, Some((dep_root, &dep)))?;
+            let cnum = self.maybe_resolve_crate(
+                dep.name,
+                dep_kind,
+                Some((dep_root, &dep)),
+                parent_is_private,
+            )?;
             crate_num_map.push(cnum);
         }
 
@@ -1133,7 +1143,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
     }
 
     pub fn maybe_process_path_extern(&mut self, name: Symbol) -> Option<CrateNum> {
-        self.maybe_resolve_crate(name, CrateDepKind::Explicit, None).ok()
+        self.maybe_resolve_crate(name, CrateDepKind::Explicit, None, false).ok()
     }
 }