Add name-resolution and HIR lowering for extern blocks

This is the initial patch to do the ground work to support extern blocks.
Type resolution and Generic output still needs to be done to actually
support extern blocks.

Addresses #421

4 files changed, 114 insertions, 0 deletions

diff --git a/gcc/rust/resolve/rust-ast-resolve-implitem.h b/gcc/rust/resolve/rust-ast-resolve-implitem.h
index 2b3a09a..6437be2 100644
--- a/gcc/rust/resolve/rust-ast-resolve-implitem.h
+++ b/gcc/rust/resolve/rust-ast-resolve-implitem.h
@@ -201,6 +201,59 @@ private:
   const CanonicalPath &prefix;
 };
 
+class ResolveToplevelExternItem : public ResolverBase
+{
+  using Rust::Resolver::ResolverBase::visit;
+
+public:
+  static void go (AST::ExternalItem *item,
+		  const CanonicalPath &prefix = CanonicalPath::create_empty ())
+  {
+    ResolveToplevelExternItem resolver (prefix);
+    item->accept_vis (resolver);
+  };
+
+  void visit (AST::ExternalFunctionItem &function) override
+  {
+    auto path
+      = prefix.append (CanonicalPath::new_seg (function.get_node_id (),
+					       function.get_identifier ()));
+    resolver->get_name_scope ().insert (
+      path, function.get_node_id (), function.get_locus (), false,
+      [&] (const CanonicalPath &, NodeId, Location locus) -> void {
+	RichLocation r (function.get_locus ());
+	r.add_range (locus);
+	rust_error_at (r, "redefined multiple times");
+      });
+    resolver->insert_new_definition (function.get_node_id (),
+				     Definition{function.get_node_id (),
+						function.get_node_id ()});
+  }
+
+  void visit (AST::ExternalStaticItem &item) override
+  {
+    auto path = prefix.append (
+      CanonicalPath::new_seg (item.get_node_id (), item.get_identifier ()));
+    resolver->get_name_scope ().insert (
+      path, item.get_node_id (), item.get_locus (), false,
+      [&] (const CanonicalPath &, NodeId, Location locus) -> void {
+	RichLocation r (item.get_locus ());
+	r.add_range (locus);
+	rust_error_at (r, "redefined multiple times");
+      });
+    resolver->insert_new_definition (item.get_node_id (),
+				     Definition{item.get_node_id (),
+						item.get_node_id ()});
+  }
+
+private:
+  ResolveToplevelExternItem (const CanonicalPath &prefix)
+    : ResolverBase (UNKNOWN_NODEID), prefix (prefix)
+  {}
+
+  const CanonicalPath &prefix;
+};
+
 } // namespace Resolver
 } // namespace Rust
 
diff --git a/gcc/rust/resolve/rust-ast-resolve-item.h b/gcc/rust/resolve/rust-ast-resolve-item.h
index 0714f5d..ccf3872 100644
--- a/gcc/rust/resolve/rust-ast-resolve-item.h
+++ b/gcc/rust/resolve/rust-ast-resolve-item.h
@@ -521,10 +521,19 @@ public:
     resolver->get_name_scope ().pop ();
   }
 
+  void visit (AST::ExternBlock &extern_block) override
+  {
+    for (auto &item : extern_block.get_extern_items ())
+      {
+	resolve_extern_item (item.get ());
+      }
+  }
+
 protected:
   void resolve_impl_item (AST::TraitImplItem *item, const CanonicalPath &self);
   void resolve_impl_item (AST::InherentImplItem *item,
 			  const CanonicalPath &self);
+  void resolve_extern_item (AST::ExternalItem *item);
 
   ResolveItem () : ResolverBase (UNKNOWN_NODEID) {}
 };
@@ -572,6 +581,46 @@ private:
   const CanonicalPath &self;
 };
 
+class ResolveExternItem : public ResolverBase
+{
+  using Rust::Resolver::ResolverBase::visit;
+
+public:
+  static void go (AST::ExternalItem *item)
+  {
+    ResolveExternItem resolver;
+    item->accept_vis (resolver);
+  };
+
+  void visit (AST::ExternalFunctionItem &function) override
+  {
+    if (function.has_generics ())
+      {
+	for (auto &generic : function.get_generic_params ())
+	  ResolveGenericParam::go (generic.get (), function.get_node_id ());
+      }
+
+    if (function.has_return_type ())
+      ResolveType::go (function.get_return_type ().get (),
+		       function.get_node_id ());
+
+    // we make a new scope so the names of parameters are resolved and shadowed
+    // correctly
+    for (auto &param : function.get_function_params ())
+      {
+	ResolveType::go (param.get_type ().get (), param.get_node_id ());
+      }
+  }
+
+  void visit (AST::ExternalStaticItem &item) override
+  {
+    ResolveType::go (item.get_type ().get (), item.get_node_id ());
+  }
+
+private:
+  ResolveExternItem () : ResolverBase (UNKNOWN_NODEID) {}
+}; // namespace Resolver
+
 } // namespace Resolver
 } // namespace Rust
 
diff --git a/gcc/rust/resolve/rust-ast-resolve-toplevel.h b/gcc/rust/resolve/rust-ast-resolve-toplevel.h
index 9abbb18..a042f5c 100644
--- a/gcc/rust/resolve/rust-ast-resolve-toplevel.h
+++ b/gcc/rust/resolve/rust-ast-resolve-toplevel.h
@@ -191,6 +191,14 @@ public:
       ResolveTopLevelTraitItems::go (item.get (), path);
   }
 
+  void visit (AST::ExternBlock &extern_block) override
+  {
+    for (auto &item : extern_block.get_extern_items ())
+      {
+	ResolveToplevelExternItem::go (item.get (), prefix);
+      }
+  }
+
 private:
   ResolveTopLevel (const CanonicalPath &prefix)
     : ResolverBase (UNKNOWN_NODEID), prefix (prefix)
diff --git a/gcc/rust/resolve/rust-ast-resolve.cc b/gcc/rust/resolve/rust-ast-resolve.cc
index 18047db..9cc833f 100644
--- a/gcc/rust/resolve/rust-ast-resolve.cc
+++ b/gcc/rust/resolve/rust-ast-resolve.cc
@@ -635,5 +635,9 @@ ResolveItem::resolve_impl_item (AST::InherentImplItem *item,
   ResolveImplItems::go (item, self);
 }
 
+void
+ResolveItem::resolve_extern_item (AST::ExternalItem *item)
+{}
+
 } // namespace Resolver
 } // namespace Rust