gccrs: Add closure binding's tracking to name resolution

When we have a closure block referencing variables in a parent function,
we must track what these are. We do this by having a context of closures
so if we have a variable reference and its declared in a rib whose node id
is less than the node id of the closure's node id we know it must be a
captured variable. We also need to iterate all possible closure contexts
as we might be in the case of a nested closure.

Addresses #195

gcc/rust/ChangeLog:

	* resolve/rust-ast-resolve-expr.cc (ResolveExpr::visit): Use proper closure
	contexts.
	* resolve/rust-name-resolver.cc (Scope::lookup_decl_type): New function.
	(Scope::lookup_rib_for_decl): Likewise.
	(Resolver::insert_resolved_name): Insert captured items.
	(Resolver::push_closure_context): New function.
	(Resolver::pop_closure_context): Likewise.
	(Resolver::insert_captured_item): Likewise.
	(Resolver::decl_needs_capture): Likewise.
	(Resolver::get_captures): Likewise.
	* resolve/rust-name-resolver.h: Declare new functions.

1 files changed, 17 insertions, 0 deletions

diff --git a/gcc/rust/resolve/rust-name-resolver.h b/gcc/rust/resolve/rust-name-resolver.h
index 54d5954..f38cbb9 100644
--- a/gcc/rust/resolve/rust-name-resolver.h
+++ b/gcc/rust/resolve/rust-name-resolver.h
@@ -96,6 +96,8 @@ public:
   void insert (const CanonicalPath &ident, NodeId id, Location locus,
 	       Rib::ItemType type = Rib::ItemType::Unknown);
   bool lookup (const CanonicalPath &ident, NodeId *id);
+  bool lookup_decl_type (NodeId id, Rib::ItemType *type);
+  bool lookup_rib_for_decl (NodeId id, const Rib **rib);
 
   void iterate (std::function<bool (Rib *)> cb);
   void iterate (std::function<bool (const Rib *)> cb) const;
@@ -109,6 +111,8 @@ public:
 
   CrateNum get_crate_num () const { return crate_num; }
 
+  const std::vector<Rib *> &get_context () const { return stack; };
+
 private:
   CrateNum crate_num;
   std::vector<Rib *> stack;
@@ -191,6 +195,15 @@ public:
     return current_module_stack.at (current_module_stack.size () - 2);
   }
 
+  void push_closure_context (NodeId closure_expr_id);
+  void pop_closure_context ();
+  void insert_captured_item (NodeId id);
+  const std::set<NodeId> &get_captures (NodeId id) const;
+
+protected:
+  bool decl_needs_capture (NodeId decl_rib_node_id, NodeId closure_rib_node_id,
+			   const Scope &scope);
+
 private:
   Resolver ();
 
@@ -234,6 +247,10 @@ private:
 
   // keep track of the current module scope ids
   std::vector<NodeId> current_module_stack;
+
+  // captured variables mappings
+  std::vector<NodeId> closure_context;
+  std::map<NodeId, std::set<NodeId>> closures_capture_mappings;
 };
 
 } // namespace Resolver