Resolve enum field visibility correctly

Previously, this code treated enum fields' visibility as if they were
struct fields. However, that's not correct because the visibility of a
struct field with `ast::VisibilityKind::Inherited` is private to the
module it's defined in, whereas the visibility of an *enum* field with
`ast::VisibilityKind::Inherited` is the visibility of the enum it
belongs to.

2 files changed, 11 insertions, 1 deletions

diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 6d7e4ebc253..06e9969697d 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -258,7 +258,16 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                 Ok(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)))
             }
             ast::VisibilityKind::Inherited => {
-                Ok(ty::Visibility::Restricted(parent_scope.module.normal_ancestor_id))
+                if matches!(self.parent_scope.module.kind, ModuleKind::Def(DefKind::Enum, _, _)) {
+                    // Any inherited visibility resolved directly inside an enum
+                    // (e.g. variants or fields) inherits from the visibility of the enum.
+                    let parent_enum = self.parent_scope.module.def_id().unwrap().expect_local();
+                    Ok(self.r.visibilities[&parent_enum])
+                } else {
+                    // If it's not in an enum, its visibility is restricted to the `mod` item
+                    // that it's defined in.
+                    Ok(ty::Visibility::Restricted(self.parent_scope.module.normal_ancestor_id))
+                }
             }
             ast::VisibilityKind::Restricted { ref path, id, .. } => {
                 // For visibilities we are not ready to provide correct implementation of "uniform
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index e8a06265ada..f764fbc3f8d 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -403,6 +403,7 @@ enum PathResult<'a> {
     },
 }
 
+#[derive(Debug)]
 enum ModuleKind {
     /// An anonymous module; e.g., just a block.
     ///