Use name resolver 2.0 during pattern typechecking

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-pattern.cc: Add includes.
	(TypeCheckPattern::visit): Use name resolver 2.0 if enabled.

	* resolve/rust-name-resolution-context.cc
	(NameResolutionContext::lookup): Make const qualified.
	* resolve/rust-name-resolution-context.h
	(NameResolutionContext::lookup): Likewise.

Signed-off-by: Owen Avery <[email protected]>

Author: powerboat9

gcc/rust/resolve/rust-name-resolution-context.cc

@@ -92,7 +92,7 @@ NameResolutionContext::map_usage (Usage usage, Definition definition)
 }
 
 tl::optional<NodeId>
-NameResolutionContext::lookup (NodeId usage)
+NameResolutionContext::lookup (NodeId usage) const
 {
   auto it = resolved_nodes.find (Usage (usage));
 

gcc/rust/resolve/rust-name-resolution-context.h

@@ -213,7 +213,7 @@ class NameResolutionContext
   // TODO: Use newtype pattern for Usage and Definition
   void map_usage (Usage usage, Definition definition);
 
-  tl::optional<NodeId> lookup (NodeId usage);
+  tl::optional<NodeId> lookup (NodeId usage) const;
 
 private:
   /* Map of "usage" nodes which have been resolved to a "definition" node */

gcc/rust/typecheck/rust-hir-type-check-pattern.cc

@@ -20,6 +20,10 @@
 #include "rust-hir-pattern.h"
 #include "rust-hir-type-check-expr.h"
 #include "rust-type-util.h"
+#include "rust-immutable-name-resolution-context.h"
+
+// for flag_name_resolution_2_0
+#include "options.h"
 
 namespace Rust {
 namespace Resolver {
@@ -49,12 +53,26 @@ TypeCheckPattern::visit (HIR::PathInExpression &pattern)
 
   NodeId ref_node_id = UNKNOWN_NODEID;
   bool maybe_item = false;
-  maybe_item
-    |= resolver->lookup_resolved_name (pattern.get_mappings ().get_nodeid (),
-				       &ref_node_id);
-  maybe_item
-    |= resolver->lookup_resolved_type (pattern.get_mappings ().get_nodeid (),
-				       &ref_node_id);
+
+  if (flag_name_resolution_2_0)
+    {
+      auto &nr_ctx
+	= Resolver2_0::ImmutableNameResolutionContext::get ().resolver ();
+
+      if (auto id = nr_ctx.lookup (pattern.get_mappings ().get_nodeid ()))
+	{
+	  ref_node_id = *id;
+	  maybe_item = true;
+	}
+    }
+  else
+    {
+      maybe_item |= resolver->lookup_resolved_name (
+	pattern.get_mappings ().get_nodeid (), &ref_node_id);
+      maybe_item |= resolver->lookup_resolved_type (
+	pattern.get_mappings ().get_nodeid (), &ref_node_id);
+    }
+
   bool path_is_const_item = false;
 
   if (maybe_item)