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, 9 insertions, 0 deletions

diff --git a/gcc/rust/resolve/rust-ast-resolve-expr.cc b/gcc/rust/resolve/rust-ast-resolve-expr.cc
index 293c63f..536c828 100644
--- a/gcc/rust/resolve/rust-ast-resolve-expr.cc
+++ b/gcc/rust/resolve/rust-ast-resolve-expr.cc
@@ -581,9 +581,13 @@ ResolveExpr::visit (AST::ClosureExprInner &expr)
       resolve_closure_param (p);
     }
 
+  resolver->push_closure_context (expr.get_node_id ());
+
   ResolveExpr::go (expr.get_definition_expr ().get (), prefix,
 		   canonical_prefix);
 
+  resolver->pop_closure_context ();
+
   resolver->get_name_scope ().pop ();
   resolver->get_type_scope ().pop ();
   resolver->get_label_scope ().pop ();
@@ -606,9 +610,14 @@ ResolveExpr::visit (AST::ClosureExprInnerTyped &expr)
     }
 
   ResolveType::go (expr.get_return_type ().get ());
+
+  resolver->push_closure_context (expr.get_node_id ());
+
   ResolveExpr::go (expr.get_definition_block ().get (), prefix,
 		   canonical_prefix);
 
+  resolver->pop_closure_context ();
+
   resolver->get_name_scope ().pop ();
   resolver->get_type_scope ().pop ();
   resolver->get_label_scope ().pop ();