mappings: Add get_lang_item_node

This method errors out if the lang item has not been declared yet.

gcc/rust/ChangeLog:

	* util/rust-hir-map.cc (Mappings::get_lang_item_node): New.
	* util/rust-hir-map.h: New function.

2 files changed, 11 insertions, 0 deletions

diff --git a/gcc/rust/util/rust-hir-map.cc b/gcc/rust/util/rust-hir-map.cc
index 2edf099..bf09c94 100644
--- a/gcc/rust/util/rust-hir-map.cc
+++ b/gcc/rust/util/rust-hir-map.cc
@@ -1299,5 +1299,15 @@ Mappings::lookup_lang_item_node (LangItem::Kind item_type)
   return it->second;
 }
 
+NodeId
+Mappings::get_lang_item_node (LangItem::Kind item_type)
+{
+  if (auto lookup = lookup_lang_item_node (item_type))
+    return *lookup;
+
+  rust_fatal_error (UNKNOWN_LOCATION, "failed to find lang item %qs",
+		    LangItem::ToString (item_type).c_str ());
+}
+
 } // namespace Analysis
 } // namespace Rust
diff --git a/gcc/rust/util/rust-hir-map.h b/gcc/rust/util/rust-hir-map.h
index 6117b0a..9cf977a 100644
--- a/gcc/rust/util/rust-hir-map.h
+++ b/gcc/rust/util/rust-hir-map.h
@@ -261,6 +261,7 @@ public:
 
   void insert_lang_item_node (LangItem::Kind item_type, NodeId node_id);
   tl::optional<NodeId &> lookup_lang_item_node (LangItem::Kind item_type);
+  NodeId get_lang_item_node (LangItem::Kind item_type);
 
   // This will fatal_error when this lang item does not exist
   DefId get_lang_item (LangItem::Kind item_type, location_t locus);