Merge #1246

1246: Report simple privacy violations r=CohenArthur a=CohenArthur

This adds a base visitor for reporting basic privacy violations. For now, only function calls are implemented.

Co-authored-by: Arthur Cohen <arthur.cohen@embecosm.com>

19 files changed, 1164 insertions, 98 deletions

diff --git a/gcc/rust/Make-lang.in b/gcc/rust/Make-lang.in
index 738cfdf..f87ad54 100644
--- a/gcc/rust/Make-lang.in
+++ b/gcc/rust/Make-lang.in
@@ -100,6 +100,7 @@ GRS_OBJS = \
     rust/rust-reachability.o \
     rust/rust-visibility-resolver.o \
     rust/rust-pub-restricted-visitor.o \
+    rust/rust-privacy-reporter.o \
     rust/rust-tyty.o \
     rust/rust-tyctx.o \
     rust/rust-tyty-bounds.o \
@@ -120,6 +121,7 @@ GRS_OBJS = \
     rust/rust-compile-pattern.o \
     rust/rust-compile-fnparam.o \
     rust/rust-base62.o \
+    rust/rust-optional-test.o \
     rust/rust-compile-item.o \
     rust/rust-compile-implitem.o \
     rust/rust-compile-expr.o \
diff --git a/gcc/rust/privacy/rust-privacy-check.cc b/gcc/rust/privacy/rust-privacy-check.cc
index b2e33c0..dca5235 100644
--- a/gcc/rust/privacy/rust-privacy-check.cc
+++ b/gcc/rust/privacy/rust-privacy-check.cc
@@ -23,6 +23,7 @@
 #include "rust-name-resolver.h"
 #include "rust-visibility-resolver.h"
 #include "rust-pub-restricted-visitor.h"
+#include "rust-privacy-reporter.h"
 
 extern bool
 saw_errors (void);
@@ -40,6 +41,7 @@ Resolver::resolve (HIR::Crate &crate)
 
   VisibilityResolver (*mappings, *resolver).go (crate);
   PubRestrictedVisitor (*mappings).go (crate);
+  PrivacyReporter (*mappings, *resolver).go (crate);
 
   auto visitor = ReachabilityVisitor (ctx, *ty_ctx);
 
diff --git a/gcc/rust/privacy/rust-privacy-common.h b/gcc/rust/privacy/rust-privacy-common.h
index a47992f..ceafe91 100644
--- a/gcc/rust/privacy/rust-privacy-common.h
+++ b/gcc/rust/privacy/rust-privacy-common.h
@@ -24,6 +24,9 @@ namespace Privacy {
 /**
  * Visibility class related specifically to DefIds. This class allows defining
  * the visibility of an item with regard to a specific module.
+ *
+ * Items are either public throughout a crate, or restricted to a specific
+ * module. Private items are simply restricted to the current module.
  */
 class ModuleVisibility
 {
@@ -31,7 +34,6 @@ public:
   enum Type
   {
     Unknown,
-    Private,
     Public,
     Restricted,
   };
diff --git a/gcc/rust/privacy/rust-privacy-reporter.cc b/gcc/rust/privacy/rust-privacy-reporter.cc
new file mode 100644
index 0000000..4c18adb
--- /dev/null
+++ b/gcc/rust/privacy/rust-privacy-reporter.cc
@@ -0,0 +1,645 @@
+#include "rust-privacy-reporter.h"
+#include "rust-hir-expr.h"
+#include "rust-hir-stmt.h"
+#include "rust-hir-item.h"
+
+namespace Rust {
+namespace Privacy {
+
+PrivacyReporter::PrivacyReporter (Analysis::Mappings &mappings,
+				  Resolver::Resolver &resolver)
+  : mappings (mappings), resolver (resolver),
+    current_module (Optional<NodeId>::none ())
+{}
+
+void
+PrivacyReporter::go (HIR::Crate &crate)
+{
+  for (auto &item : crate.items)
+    item->accept_vis (*this);
+}
+
+static bool
+is_child_module (NodeId current_module,
+		 Optional<std::vector<NodeId> &> children)
+{
+  if (!children)
+    return false;
+
+  // FIXME: This checks for one step - we need to go deeper
+  for (auto &child : *children)
+    if (child == current_module)
+      return true;
+
+  return false;
+}
+
+// FIXME: This function needs a lot of refactoring
+void
+PrivacyReporter::check_for_privacy_violation (const NodeId &use_id,
+					      const Location &locus)
+{
+  NodeId ref_node_id;
+
+  // FIXME: Don't assert here - we might be dealing with a type
+  rust_assert (resolver.lookup_resolved_name (use_id, &ref_node_id));
+
+  ModuleVisibility vis;
+
+  // FIXME: Can we really return here if the item has no visibility?
+  if (!mappings.lookup_visibility (ref_node_id, vis))
+    return;
+
+  auto valid = true;
+
+  switch (vis.get_kind ())
+    {
+    case ModuleVisibility::Public:
+      break;
+      case ModuleVisibility::Restricted: {
+	// If we are in the crate, everything is restricted correctly, but we
+	// can't get a module for it
+	if (current_module.is_none ())
+	  return;
+
+	auto module = mappings.lookup_defid (vis.get_module_id ());
+	rust_assert (module != nullptr);
+
+	auto mod_node_id = module->get_mappings ().get_nodeid ();
+
+	// We are in the module referenced by the pub(restricted) visibility.
+	// This is valid
+	if (mod_node_id == current_module.get ())
+	  break;
+
+	auto children = mappings.lookup_module_children (mod_node_id);
+
+	// FIXME: This needs a LOT of TLC: hinting about the definition, a
+	// string to say if it's a module, function, type, etc...
+	if (!is_child_module (current_module.get (), children))
+	  valid = false;
+      }
+      break;
+    case ModuleVisibility::Unknown:
+      rust_unreachable ();
+      break;
+    }
+
+  if (!valid)
+    rust_error_at (locus, "definition is private in this context");
+}
+
+void
+PrivacyReporter::visit (HIR::IdentifierExpr &ident_expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::Lifetime &lifetime)
+{}
+
+void
+PrivacyReporter::visit (HIR::LifetimeParam &lifetime_param)
+{}
+
+void
+PrivacyReporter::visit (HIR::PathInExpression &path)
+{
+  check_for_privacy_violation (path.get_mappings ().get_nodeid (),
+			       path.get_locus ());
+}
+
+void
+PrivacyReporter::visit (HIR::TypePathSegment &segment)
+{}
+
+void
+PrivacyReporter::visit (HIR::TypePathSegmentGeneric &segment)
+{}
+
+void
+PrivacyReporter::visit (HIR::TypePathSegmentFunction &segment)
+{}
+
+void
+PrivacyReporter::visit (HIR::TypePath &path)
+{}
+
+void
+PrivacyReporter::visit (HIR::QualifiedPathInExpression &path)
+{}
+
+void
+PrivacyReporter::visit (HIR::QualifiedPathInType &path)
+{}
+
+void
+PrivacyReporter::visit (HIR::LiteralExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::BorrowExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::DereferenceExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ErrorPropagationExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::NegationExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ArithmeticOrLogicalExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ComparisonExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::LazyBooleanExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::TypeCastExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::AssignmentExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::CompoundAssignmentExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::GroupedExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ArrayElemsValues &elems)
+{}
+
+void
+PrivacyReporter::visit (HIR::ArrayElemsCopied &elems)
+{}
+
+void
+PrivacyReporter::visit (HIR::ArrayExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ArrayIndexExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::TupleExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::TupleIndexExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructExprStruct &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructExprFieldIdentifier &field)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructExprFieldIdentifierValue &field)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructExprFieldIndexValue &field)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructExprStructFields &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructExprStructBase &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::CallExpr &expr)
+{
+  expr.get_fnexpr ()->accept_vis (*this);
+
+  // rust_assert (mappings.lookup_visibility (definition_id, def_vis));
+  // check_for_privacy_violation (def_vis, expr.get_locus ());
+}
+
+void
+PrivacyReporter::visit (HIR::MethodCallExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::FieldAccessExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ClosureExprInner &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::BlockExpr &expr)
+{
+  for (auto &stmt : expr.get_statements ())
+    stmt->accept_vis (*this);
+
+  auto &last_expr = expr.get_final_expr ();
+  if (last_expr)
+    last_expr->accept_vis (*this);
+}
+
+void
+PrivacyReporter::visit (HIR::ClosureExprInnerTyped &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ContinueExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::BreakExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangeFromToExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangeFromExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangeToExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangeFullExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangeFromToInclExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangeToInclExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ReturnExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::UnsafeBlockExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::LoopExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::WhileLoopExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::WhileLetLoopExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::ForLoopExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::IfExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::IfExprConseqElse &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::IfExprConseqIf &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::IfExprConseqIfLet &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::IfLetExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::IfLetExprConseqElse &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::IfLetExprConseqIf &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::IfLetExprConseqIfLet &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::MatchExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::AwaitExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::AsyncBlockExpr &expr)
+{}
+
+void
+PrivacyReporter::visit (HIR::TypeParam &param)
+{}
+
+void
+PrivacyReporter::visit (HIR::LifetimeWhereClauseItem &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::TypeBoundWhereClauseItem &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::Module &module)
+{
+  auto old_module = current_module;
+  current_module
+    = Optional<NodeId>::some (module.get_mappings ().get_nodeid ());
+
+  for (auto &item : module.get_items ())
+    item->accept_vis (*this);
+
+  current_module = old_module;
+}
+
+void
+PrivacyReporter::visit (HIR::ExternCrate &crate)
+{}
+
+void
+PrivacyReporter::visit (HIR::UseTreeGlob &use_tree)
+{}
+
+void
+PrivacyReporter::visit (HIR::UseTreeList &use_tree)
+{}
+
+void
+PrivacyReporter::visit (HIR::UseTreeRebind &use_tree)
+{}
+
+void
+PrivacyReporter::visit (HIR::UseDeclaration &use_decl)
+{}
+
+void
+PrivacyReporter::visit (HIR::Function &function)
+{
+  function.get_definition ()->accept_vis (*this);
+}
+
+void
+PrivacyReporter::visit (HIR::TypeAlias &type_alias)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructStruct &struct_item)
+{}
+
+void
+PrivacyReporter::visit (HIR::TupleStruct &tuple_struct)
+{}
+
+void
+PrivacyReporter::visit (HIR::EnumItem &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::EnumItemTuple &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::EnumItemStruct &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::EnumItemDiscriminant &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::Enum &enum_item)
+{}
+
+void
+PrivacyReporter::visit (HIR::Union &union_item)
+{}
+
+void
+PrivacyReporter::visit (HIR::ConstantItem &const_item)
+{}
+
+void
+PrivacyReporter::visit (HIR::StaticItem &static_item)
+{}
+
+void
+PrivacyReporter::visit (HIR::TraitItemFunc &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::TraitItemConst &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::TraitItemType &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::Trait &trait)
+{}
+
+void
+PrivacyReporter::visit (HIR::ImplBlock &impl)
+{}
+
+void
+PrivacyReporter::visit (HIR::ExternalStaticItem &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::ExternalFunctionItem &item)
+{}
+
+void
+PrivacyReporter::visit (HIR::ExternBlock &block)
+{}
+
+void
+PrivacyReporter::visit (HIR::LiteralPattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::IdentifierPattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::WildcardPattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangePatternBoundLiteral &bound)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangePatternBoundPath &bound)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangePatternBoundQualPath &bound)
+{}
+
+void
+PrivacyReporter::visit (HIR::RangePattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::ReferencePattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructPatternFieldTuplePat &field)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructPatternFieldIdentPat &field)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructPatternFieldIdent &field)
+{}
+
+void
+PrivacyReporter::visit (HIR::StructPattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::TupleStructItemsNoRange &tuple_items)
+{}
+
+void
+PrivacyReporter::visit (HIR::TupleStructItemsRange &tuple_items)
+{}
+
+void
+PrivacyReporter::visit (HIR::TupleStructPattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::TuplePatternItemsMultiple &tuple_items)
+{}
+
+void
+PrivacyReporter::visit (HIR::TuplePatternItemsRanged &tuple_items)
+{}
+
+void
+PrivacyReporter::visit (HIR::TuplePattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::GroupedPattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::SlicePattern &pattern)
+{}
+
+void
+PrivacyReporter::visit (HIR::EmptyStmt &stmt)
+{}
+
+void
+PrivacyReporter::visit (HIR::LetStmt &stmt)
+{}
+
+void
+PrivacyReporter::visit (HIR::ExprStmtWithoutBlock &stmt)
+{
+  stmt.get_expr ()->accept_vis (*this);
+}
+
+void
+PrivacyReporter::visit (HIR::ExprStmtWithBlock &stmt)
+{}
+
+void
+PrivacyReporter::visit (HIR::TraitBound &bound)
+{}
+
+void
+PrivacyReporter::visit (HIR::ImplTraitType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::TraitObjectType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::ParenthesisedType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::ImplTraitTypeOneBound &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::TupleType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::NeverType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::RawPointerType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::ReferenceType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::ArrayType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::SliceType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::InferredType &type)
+{}
+
+void
+PrivacyReporter::visit (HIR::BareFunctionType &type)
+{}
+
+} // namespace Privacy
+} // namespace Rust
diff --git a/gcc/rust/privacy/rust-privacy-reporter.h b/gcc/rust/privacy/rust-privacy-reporter.h
new file mode 100644
index 0000000..fafcec1
--- /dev/null
+++ b/gcc/rust/privacy/rust-privacy-reporter.h
@@ -0,0 +1,201 @@
+// Copyright (C) 2020-2022 Free Software Foundation, Inc.
+
+// This file is part of GCC.
+
+// GCC is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free
+// Software Foundation; either version 3, or (at your option) any later
+// version.
+
+// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+// for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with GCC; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#ifndef RUST_PRIVACY_REPORTER_H
+#define RUST_PRIVACY_REPORTER_H
+
+#include "rust-hir-map.h"
+#include "rust-hir-visitor.h"
+#include "rust-mapping-common.h"
+#include "rust-name-resolver.h"
+
+namespace Rust {
+namespace Privacy {
+
+/**
+ * This visitor visits all items and expressions of a crate and reports privacy
+ * violations. It should be started after using the `VisibilityResolver` visitor
+ * which resolves the visibilities of all items of a crate.
+ */
+class PrivacyReporter : public HIR::HIRFullVisitor
+{
+public:
+  PrivacyReporter (Analysis::Mappings &mappings,
+		   Rust::Resolver::Resolver &resolver);
+
+  /**
+   * Perform privacy error reporting on an entire crate
+   */
+  void go (HIR::Crate &crate);
+
+private:
+  /**
+   * Check if a given item's visibility is accessible from the current module.
+   *
+   * This function reports the errors it finds.
+   *
+   * @param use_id NodeId of the expression/statement referencing an item with
+   * 		a visibility
+   * @param locus Location of said expression/statement
+   */
+  void check_for_privacy_violation (const NodeId &use_id,
+				    const Location &locus);
+
+  virtual void visit (HIR::IdentifierExpr &ident_expr);
+  virtual void visit (HIR::Lifetime &lifetime);
+  virtual void visit (HIR::LifetimeParam &lifetime_param);
+  virtual void visit (HIR::PathInExpression &path);
+  virtual void visit (HIR::TypePathSegment &segment);
+  virtual void visit (HIR::TypePathSegmentGeneric &segment);
+  virtual void visit (HIR::TypePathSegmentFunction &segment);
+  virtual void visit (HIR::TypePath &path);
+  virtual void visit (HIR::QualifiedPathInExpression &path);
+  virtual void visit (HIR::QualifiedPathInType &path);
+  virtual void visit (HIR::LiteralExpr &expr);
+  virtual void visit (HIR::BorrowExpr &expr);
+  virtual void visit (HIR::DereferenceExpr &expr);
+  virtual void visit (HIR::ErrorPropagationExpr &expr);
+  virtual void visit (HIR::NegationExpr &expr);
+  virtual void visit (HIR::ArithmeticOrLogicalExpr &expr);
+  virtual void visit (HIR::ComparisonExpr &expr);
+  virtual void visit (HIR::LazyBooleanExpr &expr);
+  virtual void visit (HIR::TypeCastExpr &expr);
+  virtual void visit (HIR::AssignmentExpr &expr);
+  virtual void visit (HIR::CompoundAssignmentExpr &expr);
+  virtual void visit (HIR::GroupedExpr &expr);
+  virtual void visit (HIR::ArrayElemsValues &elems);
+  virtual void visit (HIR::ArrayElemsCopied &elems);
+  virtual void visit (HIR::ArrayExpr &expr);
+  virtual void visit (HIR::ArrayIndexExpr &expr);
+  virtual void visit (HIR::TupleExpr &expr);
+  virtual void visit (HIR::TupleIndexExpr &expr);
+  virtual void visit (HIR::StructExprStruct &expr);
+  virtual void visit (HIR::StructExprFieldIdentifier &field);
+  virtual void visit (HIR::StructExprFieldIdentifierValue &field);
+  virtual void visit (HIR::StructExprFieldIndexValue &field);
+  virtual void visit (HIR::StructExprStructFields &expr);
+  virtual void visit (HIR::StructExprStructBase &expr);
+  virtual void visit (HIR::CallExpr &expr);
+  virtual void visit (HIR::MethodCallExpr &expr);
+  virtual void visit (HIR::FieldAccessExpr &expr);
+  virtual void visit (HIR::ClosureExprInner &expr);
+  virtual void visit (HIR::BlockExpr &expr);
+  virtual void visit (HIR::ClosureExprInnerTyped &expr);
+  virtual void visit (HIR::ContinueExpr &expr);
+  virtual void visit (HIR::BreakExpr &expr);
+  virtual void visit (HIR::RangeFromToExpr &expr);
+  virtual void visit (HIR::RangeFromExpr &expr);
+  virtual void visit (HIR::RangeToExpr &expr);
+  virtual void visit (HIR::RangeFullExpr &expr);
+  virtual void visit (HIR::RangeFromToInclExpr &expr);
+  virtual void visit (HIR::RangeToInclExpr &expr);
+  virtual void visit (HIR::ReturnExpr &expr);
+  virtual void visit (HIR::UnsafeBlockExpr &expr);
+  virtual void visit (HIR::LoopExpr &expr);
+  virtual void visit (HIR::WhileLoopExpr &expr);
+  virtual void visit (HIR::WhileLetLoopExpr &expr);
+  virtual void visit (HIR::ForLoopExpr &expr);
+  virtual void visit (HIR::IfExpr &expr);
+  virtual void visit (HIR::IfExprConseqElse &expr);
+  virtual void visit (HIR::IfExprConseqIf &expr);
+  virtual void visit (HIR::IfExprConseqIfLet &expr);
+  virtual void visit (HIR::IfLetExpr &expr);
+  virtual void visit (HIR::IfLetExprConseqElse &expr);
+  virtual void visit (HIR::IfLetExprConseqIf &expr);
+  virtual void visit (HIR::IfLetExprConseqIfLet &expr);
+  virtual void visit (HIR::MatchExpr &expr);
+  virtual void visit (HIR::AwaitExpr &expr);
+  virtual void visit (HIR::AsyncBlockExpr &expr);
+  virtual void visit (HIR::TypeParam &param);
+  virtual void visit (HIR::LifetimeWhereClauseItem &item);
+  virtual void visit (HIR::TypeBoundWhereClauseItem &item);
+  virtual void visit (HIR::Module &module);
+  virtual void visit (HIR::ExternCrate &crate);
+  virtual void visit (HIR::UseTreeGlob &use_tree);
+  virtual void visit (HIR::UseTreeList &use_tree);
+  virtual void visit (HIR::UseTreeRebind &use_tree);
+  virtual void visit (HIR::UseDeclaration &use_decl);
+  virtual void visit (HIR::Function &function);
+  virtual void visit (HIR::TypeAlias &type_alias);
+  virtual void visit (HIR::StructStruct &struct_item);
+  virtual void visit (HIR::TupleStruct &tuple_struct);
+  virtual void visit (HIR::EnumItem &item);
+  virtual void visit (HIR::EnumItemTuple &item);
+  virtual void visit (HIR::EnumItemStruct &item);
+  virtual void visit (HIR::EnumItemDiscriminant &item);
+  virtual void visit (HIR::Enum &enum_item);
+  virtual void visit (HIR::Union &union_item);
+  virtual void visit (HIR::ConstantItem &const_item);
+  virtual void visit (HIR::StaticItem &static_item);
+  virtual void visit (HIR::TraitItemFunc &item);
+  virtual void visit (HIR::TraitItemConst &item);
+  virtual void visit (HIR::TraitItemType &item);
+  virtual void visit (HIR::Trait &trait);
+  virtual void visit (HIR::ImplBlock &impl);
+  virtual void visit (HIR::ExternalStaticItem &item);
+  virtual void visit (HIR::ExternalFunctionItem &item);
+  virtual void visit (HIR::ExternBlock &block);
+  virtual void visit (HIR::LiteralPattern &pattern);
+  virtual void visit (HIR::IdentifierPattern &pattern);
+  virtual void visit (HIR::WildcardPattern &pattern);
+  virtual void visit (HIR::RangePatternBoundLiteral &bound);
+  virtual void visit (HIR::RangePatternBoundPath &bound);
+  virtual void visit (HIR::RangePatternBoundQualPath &bound);
+  virtual void visit (HIR::RangePattern &pattern);
+  virtual void visit (HIR::ReferencePattern &pattern);
+  virtual void visit (HIR::StructPatternFieldTuplePat &field);
+  virtual void visit (HIR::StructPatternFieldIdentPat &field);
+  virtual void visit (HIR::StructPatternFieldIdent &field);
+  virtual void visit (HIR::StructPattern &pattern);
+  virtual void visit (HIR::TupleStructItemsNoRange &tuple_items);
+  virtual void visit (HIR::TupleStructItemsRange &tuple_items);
+  virtual void visit (HIR::TupleStructPattern &pattern);
+  virtual void visit (HIR::TuplePatternItemsMultiple &tuple_items);
+  virtual void visit (HIR::TuplePatternItemsRanged &tuple_items);
+  virtual void visit (HIR::TuplePattern &pattern);
+  virtual void visit (HIR::GroupedPattern &pattern);
+  virtual void visit (HIR::SlicePattern &pattern);
+  virtual void visit (HIR::EmptyStmt &stmt);
+  virtual void visit (HIR::LetStmt &stmt);
+  virtual void visit (HIR::ExprStmtWithoutBlock &stmt);
+  virtual void visit (HIR::ExprStmtWithBlock &stmt);
+  virtual void visit (HIR::TraitBound &bound);
+  virtual void visit (HIR::ImplTraitType &type);
+  virtual void visit (HIR::TraitObjectType &type);
+  virtual void visit (HIR::ParenthesisedType &type);
+  virtual void visit (HIR::ImplTraitTypeOneBound &type);
+  virtual void visit (HIR::TupleType &type);
+  virtual void visit (HIR::NeverType &type);
+  virtual void visit (HIR::RawPointerType &type);
+  virtual void visit (HIR::ReferenceType &type);
+  virtual void visit (HIR::ArrayType &type);
+  virtual void visit (HIR::SliceType &type);
+  virtual void visit (HIR::InferredType &type);
+  virtual void visit (HIR::BareFunctionType &type);
+
+  Analysis::Mappings &mappings;
+  Rust::Resolver::Resolver &resolver;
+
+  // `None` means we're in the root module - the crate
+  Optional<NodeId> current_module;
+};
+
+} // namespace Privacy
+} // namespace Rust
+
+#endif // !RUST_PRIVACY_REPORTER_H
diff --git a/gcc/rust/privacy/rust-pub-restricted-visitor.cc b/gcc/rust/privacy/rust-pub-restricted-visitor.cc
index ca50fe3..e391653 100644
--- a/gcc/rust/privacy/rust-pub-restricted-visitor.cc
+++ b/gcc/rust/privacy/rust-pub-restricted-visitor.cc
@@ -24,14 +24,15 @@ namespace Rust {
 namespace Privacy {
 
 bool
-PubRestrictedVisitor::is_restriction_valid (DefId item_id,
+PubRestrictedVisitor::is_restriction_valid (NodeId item_id,
 					    const Location &locus)
 {
   ModuleVisibility visibility;
 
   // If there is no visibility in the mappings, then the item is private and
   // does not contain any restriction
-  if (!mappings.lookup_visibility (item_id, &visibility))
+  // FIXME: Is that correct?
+  if (!mappings.lookup_visibility (item_id, visibility))
     return true;
 
   for (auto mod = module_stack.rbegin (); mod != module_stack.rend (); mod++)
@@ -72,7 +73,7 @@ PubRestrictedVisitor::visit (HIR::Module &mod)
   // FIXME: We need to update `super` and `self` here
   module_stack.push_back (mod.get_mappings ().get_defid ());
 
-  is_restriction_valid (mod.get_mappings ().get_defid (), mod.get_locus ());
+  is_restriction_valid (mod.get_mappings ().get_nodeid (), mod.get_locus ());
 
   for (auto &item : mod.get_items ())
     {
@@ -89,33 +90,34 @@ PubRestrictedVisitor::visit (HIR::Module &mod)
 void
 PubRestrictedVisitor::visit (HIR::ExternCrate &crate)
 {
-  is_restriction_valid (crate.get_mappings ().get_defid (), crate.get_locus ());
+  is_restriction_valid (crate.get_mappings ().get_nodeid (),
+			crate.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::UseDeclaration &use_decl)
 {
-  is_restriction_valid (use_decl.get_mappings ().get_defid (),
+  is_restriction_valid (use_decl.get_mappings ().get_nodeid (),
 			use_decl.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::Function &func)
 {
-  is_restriction_valid (func.get_mappings ().get_defid (), func.get_locus ());
+  is_restriction_valid (func.get_mappings ().get_nodeid (), func.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::TypeAlias &type_alias)
 {
-  is_restriction_valid (type_alias.get_mappings ().get_defid (),
+  is_restriction_valid (type_alias.get_mappings ().get_nodeid (),
 			type_alias.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::StructStruct &struct_item)
 {
-  is_restriction_valid (struct_item.get_mappings ().get_defid (),
+  is_restriction_valid (struct_item.get_mappings ().get_nodeid (),
 			struct_item.get_locus ());
   // FIXME: Check fields here as well
 }
@@ -123,7 +125,7 @@ PubRestrictedVisitor::visit (HIR::StructStruct &struct_item)
 void
 PubRestrictedVisitor::visit (HIR::TupleStruct &tuple_struct)
 {
-  is_restriction_valid (tuple_struct.get_mappings ().get_defid (),
+  is_restriction_valid (tuple_struct.get_mappings ().get_nodeid (),
 			tuple_struct.get_locus ());
   // FIXME: Check fields here as well
 }
@@ -131,47 +133,49 @@ PubRestrictedVisitor::visit (HIR::TupleStruct &tuple_struct)
 void
 PubRestrictedVisitor::visit (HIR::Enum &enum_item)
 {
-  is_restriction_valid (enum_item.get_mappings ().get_defid (),
+  is_restriction_valid (enum_item.get_mappings ().get_nodeid (),
 			enum_item.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::Union &union_item)
 {
-  is_restriction_valid (union_item.get_mappings ().get_defid (),
+  is_restriction_valid (union_item.get_mappings ().get_nodeid (),
 			union_item.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::ConstantItem &const_item)
 {
-  is_restriction_valid (const_item.get_mappings ().get_defid (),
+  is_restriction_valid (const_item.get_mappings ().get_nodeid (),
 			const_item.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::StaticItem &static_item)
 {
-  is_restriction_valid (static_item.get_mappings ().get_defid (),
+  is_restriction_valid (static_item.get_mappings ().get_nodeid (),
 			static_item.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::Trait &trait)
 {
-  is_restriction_valid (trait.get_mappings ().get_defid (), trait.get_locus ());
+  is_restriction_valid (trait.get_mappings ().get_nodeid (),
+			trait.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::ImplBlock &impl)
 {
-  is_restriction_valid (impl.get_mappings ().get_defid (), impl.get_locus ());
+  is_restriction_valid (impl.get_mappings ().get_nodeid (), impl.get_locus ());
 }
 
 void
 PubRestrictedVisitor::visit (HIR::ExternBlock &block)
 {
-  is_restriction_valid (block.get_mappings ().get_defid (), block.get_locus ());
+  is_restriction_valid (block.get_mappings ().get_nodeid (),
+			block.get_locus ());
 }
 
 } // namespace Privacy
diff --git a/gcc/rust/privacy/rust-pub-restricted-visitor.h b/gcc/rust/privacy/rust-pub-restricted-visitor.h
index dc725e1..2685f3d 100644
--- a/gcc/rust/privacy/rust-pub-restricted-visitor.h
+++ b/gcc/rust/privacy/rust-pub-restricted-visitor.h
@@ -82,12 +82,12 @@ public:
    *
    * In case of error, this function will emit the errors and return.
    *
-   * @param item_id DefId of the item to check the restriction of
+   * @param item_id NodeId of the item to check the restriction of
    * @param locus Location of the item being checked
    *
    * @return true if the visibility restriction is valid, false otherwise.
    */
-  bool is_restriction_valid (DefId item_id, const Location &locus);
+  bool is_restriction_valid (NodeId item_id, const Location &locus);
 
   virtual void visit (HIR::Module &mod);
   virtual void visit (HIR::ExternCrate &crate);
diff --git a/gcc/rust/privacy/rust-visibility-resolver.cc b/gcc/rust/privacy/rust-visibility-resolver.cc
index 38d6403..421dff0 100644
--- a/gcc/rust/privacy/rust-visibility-resolver.cc
+++ b/gcc/rust/privacy/rust-visibility-resolver.cc
@@ -32,9 +32,11 @@ VisibilityResolver::VisibilityResolver (Analysis::Mappings &mappings,
 void
 VisibilityResolver::go (HIR::Crate &crate)
 {
-  mappings.insert_visibility (crate.get_mappings ().get_defid (),
+  mappings.insert_visibility (crate.get_mappings ().get_nodeid (),
 			      ModuleVisibility::create_public ());
 
+  current_module = crate.get_mappings ().get_defid ();
+
   for (auto &item : crate.items)
     {
       if (item->get_hir_kind () == HIR::Node::VIS_ITEM)
@@ -103,15 +105,18 @@ VisibilityResolver::resolve_visibility (const HIR::Visibility &visibility,
   switch (visibility.get_vis_type ())
     {
     case HIR::Visibility::PRIVATE:
+      to_resolve = ModuleVisibility::create_restricted (current_module);
       return true;
     case HIR::Visibility::PUBLIC:
       to_resolve = ModuleVisibility::create_public ();
       return true;
-    case HIR::Visibility::RESTRICTED:
-      // FIXME: We also need to handle 2015 vs 2018 edition conflicts
-      to_resolve = ModuleVisibility::create_public ();
-      return resolve_module_path (visibility.get_path (),
-				  to_resolve.get_module_id ());
+      case HIR::Visibility::RESTRICTED: {
+	// FIXME: We also need to handle 2015 vs 2018 edition conflicts
+	auto id = UNKNOWN_DEFID;
+	auto result = resolve_module_path (visibility.get_path (), id);
+	to_resolve = ModuleVisibility::create_restricted (id);
+	return result;
+      }
     default:
       gcc_unreachable ();
       return false;
@@ -125,12 +130,15 @@ VisibilityResolver::resolve_and_update (const HIR::VisItem *item)
   if (!resolve_visibility (item->get_visibility (), module_vis))
     return; // we will already have emitted errors
 
-  mappings.insert_visibility (item->get_mappings ().get_defid (), module_vis);
+  mappings.insert_visibility (item->get_mappings ().get_nodeid (), module_vis);
 }
 
 void
 VisibilityResolver::visit (HIR::Module &mod)
 {
+  auto old_module = current_module;
+  current_module = mod.get_mappings ().get_defid ();
+
   for (auto &item : mod.get_items ())
     {
       if (item->get_hir_kind () == HIR::Node::VIS_ITEM)
@@ -139,6 +147,8 @@ VisibilityResolver::visit (HIR::Module &mod)
 	  vis_item->accept_vis (*this);
 	}
     }
+
+  current_module = old_module;
 }
 
 void
@@ -180,9 +190,9 @@ VisibilityResolver::visit (HIR::Enum &enum_item)
   if (!resolve_visibility (enum_item.get_visibility (), vis))
     return;
 
-  mappings.insert_visibility (enum_item.get_mappings ().get_defid (), vis);
+  mappings.insert_visibility (enum_item.get_mappings ().get_nodeid (), vis);
   for (auto &variant : enum_item.get_variants ())
-    mappings.insert_visibility (variant->get_mappings ().get_defid (), vis);
+    mappings.insert_visibility (variant->get_mappings ().get_nodeid (), vis);
 }
 
 void
@@ -208,9 +218,9 @@ VisibilityResolver::visit (HIR::Trait &trait)
   if (!resolve_visibility (trait.get_visibility (), vis))
     return;
 
-  mappings.insert_visibility (trait.get_mappings ().get_defid (), vis);
+  mappings.insert_visibility (trait.get_mappings ().get_nodeid (), vis);
   for (auto &item : trait.get_trait_items ())
-    mappings.insert_visibility (item->get_mappings ().get_defid (), vis);
+    mappings.insert_visibility (item->get_mappings ().get_nodeid (), vis);
 }
 
 void
diff --git a/gcc/rust/privacy/rust-visibility-resolver.h b/gcc/rust/privacy/rust-visibility-resolver.h
index c57d518..20a581c 100644
--- a/gcc/rust/privacy/rust-visibility-resolver.h
+++ b/gcc/rust/privacy/rust-visibility-resolver.h
@@ -94,6 +94,7 @@ public:
 private:
   Analysis::Mappings &mappings;
   Rust::Resolver::Resolver &resolver;
+  DefId current_module;
 };
 
 } // namespace Privacy
diff --git a/gcc/rust/resolve/rust-ast-resolve-base.h b/gcc/rust/resolve/rust-ast-resolve-base.h
index 17d05c3..9c1f0a1 100644
--- a/gcc/rust/resolve/rust-ast-resolve-base.h
+++ b/gcc/rust/resolve/rust-ast-resolve-base.h
@@ -199,9 +199,10 @@ public:
   void visit (AST::BareFunctionType &);
 
 protected:
-  ResolverBase (NodeId parent)
+  ResolverBase (NodeId parent, NodeId current_module = UNKNOWN_NODEID)
     : resolver (Resolver::get ()), mappings (Analysis::Mappings::get ()),
-      resolved_node (UNKNOWN_NODEID), parent (parent), locus (Location ())
+      resolved_node (UNKNOWN_NODEID), parent (parent),
+      current_module (current_module), locus (Location ())
   {}
 
   bool resolved () const { return resolved_node != UNKNOWN_NODEID; }
@@ -215,6 +216,7 @@ protected:
   Analysis::Mappings *mappings;
   NodeId resolved_node;
   NodeId parent;
+  NodeId current_module;
   Location locus;
 };
 
diff --git a/gcc/rust/resolve/rust-ast-resolve-item.cc b/gcc/rust/resolve/rust-ast-resolve-item.cc
index 93eca1b..38e7713 100644
--- a/gcc/rust/resolve/rust-ast-resolve-item.cc
+++ b/gcc/rust/resolve/rust-ast-resolve-item.cc
@@ -250,8 +250,11 @@ ResolveItem::visit (AST::Module &module)
   resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
   resolver->push_new_label_rib (resolver->get_type_scope ().peek ());
 
+  // FIXME: Should we reinsert a child here? Any reason we ResolveTopLevel::go
+  // in ResolveTopLevel::visit (AST::Module) as well as here?
   for (auto &item : module.get_items ())
-    ResolveTopLevel::go (item.get (), CanonicalPath::create_empty (), cpath);
+    ResolveTopLevel::go (item.get (), CanonicalPath::create_empty (), cpath,
+			 module.get_node_id ());
 
   for (auto &item : module.get_items ())
     ResolveItem::go (item.get (), path, cpath);
diff --git a/gcc/rust/resolve/rust-ast-resolve-toplevel.h b/gcc/rust/resolve/rust-ast-resolve-toplevel.h
index 7aba67f..7cfaa72 100644
--- a/gcc/rust/resolve/rust-ast-resolve-toplevel.h
+++ b/gcc/rust/resolve/rust-ast-resolve-toplevel.h
@@ -34,12 +34,12 @@ class ResolveTopLevel : public ResolverBase
 
 public:
   static void go (AST::Item *item, const CanonicalPath &prefix,
-		  const CanonicalPath &canonical_prefix)
+		  const CanonicalPath &canonical_prefix, NodeId current_module)
   {
     if (item->is_marked_for_strip ())
       return;
 
-    ResolveTopLevel resolver (prefix, canonical_prefix);
+    ResolveTopLevel resolver (prefix, canonical_prefix, current_module);
     item->accept_vis (resolver);
   };
 
@@ -62,8 +62,10 @@ public:
 				     Definition{module.get_node_id (),
 						module.get_node_id ()});
 
+    mappings->insert_module_child (current_module, module.get_node_id ());
+
     for (auto &item : module.get_items ())
-      ResolveTopLevel::go (item.get (), path, cpath);
+      ResolveTopLevel::go (item.get (), path, cpath, module.get_node_id ());
 
     mappings->insert_canonical_path (mappings->get_current_crate (),
 				     module.get_node_id (), cpath);
@@ -123,7 +125,7 @@ public:
       });
 
     for (auto &variant : enum_decl.get_variants ())
-      ResolveTopLevel::go (variant.get (), path, cpath);
+      ResolveTopLevel::go (variant.get (), path, cpath, current_module);
 
     mappings->insert_canonical_path (mappings->get_current_crate (),
 				     enum_decl.get_node_id (), cpath);
@@ -403,8 +405,8 @@ public:
 
 private:
   ResolveTopLevel (const CanonicalPath &prefix,
-		   const CanonicalPath &canonical_prefix)
-    : ResolverBase (UNKNOWN_NODEID), prefix (prefix),
+		   const CanonicalPath &canonical_prefix, NodeId current_module)
+    : ResolverBase (UNKNOWN_NODEID, current_module), prefix (prefix),
       canonical_prefix (canonical_prefix)
   {}
 
diff --git a/gcc/rust/resolve/rust-ast-resolve.cc b/gcc/rust/resolve/rust-ast-resolve.cc
index 6da5609..945ff28 100644
--- a/gcc/rust/resolve/rust-ast-resolve.cc
+++ b/gcc/rust/resolve/rust-ast-resolve.cc
@@ -86,7 +86,7 @@ NameResolution::go (AST::Crate &crate)
   // a Self type Foo which is defined after the impl block for example.
   for (auto it = crate.items.begin (); it != crate.items.end (); it++)
     ResolveTopLevel::go (it->get (), CanonicalPath::create_empty (),
-			 crate_prefix);
+			 crate_prefix, scope_node_id);
 
   // FIXME remove this
   if (saw_errors ())
diff --git a/gcc/rust/util/rust-hir-map.cc b/gcc/rust/util/rust-hir-map.cc
index 66d3e41..934331b 100644
--- a/gcc/rust/util/rust-hir-map.cc
+++ b/gcc/rust/util/rust-hir-map.cc
@@ -832,21 +832,41 @@ Mappings::lookup_macro_def (NodeId id, AST::MacroRulesDefinition **def)
 }
 
 void
-Mappings::insert_visibility (DefId id, Privacy::ModuleVisibility visibility)
+Mappings::insert_visibility (NodeId id, Privacy::ModuleVisibility visibility)
 {
   visibility_map.insert ({id, visibility});
 }
 
 bool
-Mappings::lookup_visibility (DefId id, Privacy::ModuleVisibility *def)
+Mappings::lookup_visibility (NodeId id, Privacy::ModuleVisibility &def)
 {
   auto it = visibility_map.find (id);
   if (it == visibility_map.end ())
     return false;
 
-  *def = it->second;
+  def = it->second;
   return true;
 }
 
+void
+Mappings::insert_module_child (NodeId module, NodeId child)
+{
+  auto it = module_child_map.find (module);
+  if (it == module_child_map.end ())
+    module_child_map.insert ({module, {child}});
+  else
+    it->second.emplace_back (child);
+}
+
+Optional<std::vector<NodeId> &>
+Mappings::lookup_module_children (NodeId module)
+{
+  auto it = module_child_map.find (module);
+  if (it == module_child_map.end ())
+    return Optional<std::vector<NodeId> &>::none ();
+
+  return Optional<std::vector<NodeId> &>::some (it->second);
+}
+
 } // namespace Analysis
 } // namespace Rust
diff --git a/gcc/rust/util/rust-hir-map.h b/gcc/rust/util/rust-hir-map.h
index 0bb870b..03bfd5f 100644
--- a/gcc/rust/util/rust-hir-map.h
+++ b/gcc/rust/util/rust-hir-map.h
@@ -19,6 +19,7 @@
 #ifndef RUST_HIR_MAP_H
 #define RUST_HIR_MAP_H
 
+#include "rust-optional.h"
 #include "rust-system.h"
 #include "rust-location.h"
 #include "rust-mapping-common.h"
@@ -318,8 +319,11 @@ public:
 
   bool lookup_macro_def (NodeId id, AST::MacroRulesDefinition **def);
 
-  void insert_visibility (DefId id, Privacy::ModuleVisibility visibility);
-  bool lookup_visibility (DefId id, Privacy::ModuleVisibility *def);
+  void insert_visibility (NodeId id, Privacy::ModuleVisibility visibility);
+  bool lookup_visibility (NodeId id, Privacy::ModuleVisibility &def);
+
+  void insert_module_child (NodeId module, NodeId child);
+  Optional<std::vector<NodeId> &> lookup_module_children (NodeId module);
 
 private:
   Mappings ();
@@ -385,7 +389,12 @@ private:
   std::map<CrateNum, std::string> crate_names;
 
   // Low level visibility map for each DefId
-  std::map<DefId, Privacy::ModuleVisibility> visibility_map;
+  std::map<NodeId, Privacy::ModuleVisibility> visibility_map;
+
+  // Module tree maps
+
+  // Maps each module's node id to a list of its children
+  std::map<NodeId, std::vector<NodeId>> module_child_map;
 };
 
 } // namespace Analysis
diff --git a/gcc/rust/util/rust-optional-test.cc b/gcc/rust/util/rust-optional-test.cc
new file mode 100644
index 0000000..9045ac3
--- /dev/null
+++ b/gcc/rust/util/rust-optional-test.cc
@@ -0,0 +1,104 @@
+// Copyright (C) 2020-2022 Free Software Foundation, Inc.
+
+// This file is part of GCC.
+
+// GCC is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free
+// Software Foundation; either version 3, or (at your option) any later
+// version.
+
+// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+// for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with GCC; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include "rust-optional.h"
+
+#include "config.h"
+#include "selftest.h"
+
+static void
+rust_optional_create ()
+{
+  auto opt = Rust::Optional<int>::some (15);
+
+  ASSERT_TRUE (opt.is_some ());
+  ASSERT_EQ (opt.get (), 15);
+
+  Rust::Optional<int> const_opt = Rust::Optional<int>::some (15);
+  const int &value = const_opt.get ();
+
+  ASSERT_EQ (value, 15);
+}
+
+static void
+rust_optional_operators ()
+{
+  auto opt = Rust::Optional<int>::some (15);
+
+  // as bool
+  ASSERT_TRUE (opt);
+
+  // deref
+  ASSERT_EQ (*opt, 15);
+
+  class Methodable
+  {
+  public:
+    int method () { return 15; }
+  };
+
+  auto m_opt = Rust::Optional<Methodable>::some (Methodable ());
+  ASSERT_EQ (m_opt->method (), 15);
+}
+
+static void
+rust_optional_take ()
+{
+  auto opt = Rust::Optional<int>::some (15);
+  auto value = opt.take ();
+
+  ASSERT_EQ (value, 15);
+  ASSERT_TRUE (opt.is_none ());
+}
+
+static void
+rust_optional_map ()
+{
+  auto opt = Rust::Optional<int>::some (15);
+  auto twice = opt.map<int> ([] (int value) { return value * 2; });
+
+  ASSERT_FALSE (opt);
+  ASSERT_TRUE (twice);
+  ASSERT_EQ (*twice, 30);
+}
+
+static void
+rust_optional_reference ()
+{
+  auto value = std::vector<std::string> ();
+  value.emplace_back ("rust");
+  value.emplace_back ("+");
+  value.emplace_back ("gcc");
+  value.emplace_back ("=");
+  value.emplace_back ("<3");
+
+  auto opt = Rust::Optional<std::vector<std::string> &>::some (value);
+
+  ASSERT_EQ (opt->at (0), "rust");
+  ASSERT_EQ (opt->at (2), "gcc");
+}
+
+void
+rust_optional_test ()
+{
+  rust_optional_create ();
+  rust_optional_operators ();
+  rust_optional_take ();
+  rust_optional_map ();
+  rust_optional_reference ();
+}
diff --git a/gcc/rust/util/rust-optional.h b/gcc/rust/util/rust-optional.h
index c1b547a..5646540 100644
--- a/gcc/rust/util/rust-optional.h
+++ b/gcc/rust/util/rust-optional.h
@@ -96,6 +96,7 @@ private:
 
 public:
   Optional (const Optional &other) = default;
+  Optional &operator= (const Optional &other) = default;
   Optional (Optional &&other) = default;
 
   static Optional<T> some (T value)
@@ -167,74 +168,110 @@ public:
   }
 };
 
-} // namespace Rust
+template <typename T> class Optional<T &>
+{
+private:
+  struct Empty
+  {
+  };
 
-#ifdef CHECKING_P
+  enum Kind
+  {
+    Some,
+    None
+  } kind;
 
-static void
-rust_optional_create ()
-{
-  auto opt = Rust::Optional<int>::some (15);
+  union Content
+  {
+    Empty empty;
+    T *value;
 
-  ASSERT_TRUE (opt.is_some ());
-  ASSERT_EQ (opt.get (), 15);
+    Content () = default;
+  } content;
 
-  Rust::Optional<int> const_opt = Rust::Optional<int>::some (15);
-  const int &value = const_opt.get ();
+  Optional<T &> (Kind kind, Content content) : kind (kind), content (content) {}
 
-  ASSERT_EQ (value, 15);
-}
+public:
+  Optional (const Optional &other) = default;
+  Optional (Optional &&other) = default;
 
-static void
-rust_optional_operators ()
-{
-  auto opt = Rust::Optional<int>::some (15);
+  static Optional<T &> some (T &value)
+  {
+    Content content;
+    content.value = &value;
+
+    return Optional (Kind::Some, content);
+  }
+
+  static Optional<T &> none ()
+  {
+    Content content;
+    content.empty = Empty ();
+
+    return Optional (Kind::None, content);
+  }
+
+  bool is_some () const { return kind == Kind::Some; }
+  bool is_none () const { return !is_some (); }
+
+  // FIXME: Can we factor this in a single class?
+
+  /**
+   * Enable boolean-like comparisons.
+   */
+  operator bool () { return is_some (); }
 
-  // as bool
-  ASSERT_TRUE (opt);
+  /**
+   * Enables dereferencing to access the contained value
+   */
+  T &operator* () { return get (); }
+  const T &operator* () const { return get (); }
+  T *operator-> () { return &get (); }
+  const T *operator-> () const { return &get (); }
 
-  // deref
-  ASSERT_EQ (*opt, 15);
+  const T &get () const
+  {
+    rust_assert (is_some ());
+
+    return *content.value;
+  }
 
-  class Methodable
+  T &get ()
   {
-  public:
-    int method () { return 15; }
-  };
+    rust_assert (is_some ());
 
-  auto m_opt = Rust::Optional<Methodable>::some (Methodable ());
-  ASSERT_EQ (m_opt->method (), 15);
-}
+    return *content.value;
+  }
 
-static void
-rust_optional_take ()
-{
-  auto opt = Rust::Optional<int>::some (15);
-  auto value = opt.take ();
+  T &take ()
+  {
+    rust_assert (is_some ());
 
-  ASSERT_EQ (value, 15);
-  ASSERT_TRUE (opt.is_none ());
-}
+    auto to_return = std::move (content.value);
 
-static void
-rust_optional_map ()
-{
-  auto opt = Rust::Optional<int>::some (15);
-  auto twice = opt.map<int> ([] (int value) { return value * 2; });
+    content.empty = Empty ();
+    kind = Kind::None;
+
+    return *to_return;
+  }
 
-  ASSERT_FALSE (opt);
-  ASSERT_TRUE (twice);
-  ASSERT_EQ (*twice, 30);
-}
+  template <typename U> Optional<U &> map (std::function<U &(T &)> functor)
+  {
+    if (is_none ())
+      return Optional::none ();
 
-static void
-rust_optional_test ()
-{
-  rust_optional_create ();
-  rust_optional_operators ();
-  rust_optional_take ();
-  rust_optional_map ();
-}
+    auto value = functor (take ());
+
+    return Optional::some (value);
+  }
+};
+
+} // namespace Rust
+
+#ifdef CHECKING_P
+
+void
+rust_optional_test ();
 
 #endif // !CHECKING_P
 
diff --git a/gcc/testsuite/rust/compile/privacy1.rs b/gcc/testsuite/rust/compile/privacy1.rs
new file mode 100644
index 0000000..1cc83c0
--- /dev/null
+++ b/gcc/testsuite/rust/compile/privacy1.rs
@@ -0,0 +1,11 @@
+mod orange {
+    mod green {
+        fn sain() {}
+        pub fn doux() {}
+    }
+
+    fn brown() {
+        green::sain(); // { dg-error "definition is private in this context" }
+        green::doux();
+    }
+}
diff --git a/gcc/testsuite/rust/compile/pub_restricted_3.rs b/gcc/testsuite/rust/compile/pub_restricted_3.rs
new file mode 100644
index 0000000..d477385
--- /dev/null
+++ b/gcc/testsuite/rust/compile/pub_restricted_3.rs
@@ -0,0 +1,11 @@
+// { dg-additional-options "-w" }
+
+mod foo {
+    mod bar {
+        pub(in foo) fn baz() {}
+    }
+
+    fn baz() {
+        bar::baz(); // no error, foo::bar::baz is public in foo
+    }
+}