lower: Correctly lower parenthesized types

This is useful for handling multiple trait bounds, and required for better handling of auto traits.

gcc/rust/ChangeLog:

	* hir/rust-ast-lower-type.cc (ASTLoweringType::visit): Add implementation for
	ParenthesizedType.
	* hir/rust-ast-lower-type.h: Declare that new visitor.

gcc/testsuite/ChangeLog:

	* rust/compile/auto_traits1.rs: New test.

2 files changed, 21 insertions, 0 deletions

diff --git a/gcc/rust/hir/rust-ast-lower-type.cc b/gcc/rust/hir/rust-ast-lower-type.cc
index 2c124d1..605a2e5 100644
--- a/gcc/rust/hir/rust-ast-lower-type.cc
+++ b/gcc/rust/hir/rust-ast-lower-type.cc
@@ -19,6 +19,7 @@
 #include "rust-ast-lower-type.h"
 #include "rust-hir-map.h"
 #include "rust-hir-path.h"
+#include "rust-hir-type.h"
 #include "rust-path.h"
 #include "rust-pattern.h"
 
@@ -471,6 +472,24 @@ ASTLoweringType::visit (AST::TraitObjectType &type)
 					 type.get_locus (), type.is_dyn ());
 }
 
+void
+ASTLoweringType::visit (AST::ParenthesisedType &type)
+{
+  auto *inner = ASTLoweringType::translate (*type.get_type_in_parens (),
+					    default_to_static_lifetime);
+
+  auto crate_num = mappings.get_current_crate ();
+  Analysis::NodeMapping mapping (crate_num, type.get_node_id (),
+				 mappings.get_next_hir_id (crate_num),
+				 mappings.get_next_localdef_id (crate_num));
+
+  // FIXME: Do we actually need to know if a type is parenthesized in the HIR?
+  // or can we just use the type in parens?
+  translated
+    = new HIR::ParenthesisedType (mapping, std::unique_ptr<HIR::Type> (inner),
+				  type.get_locus ());
+}
+
 HIR::GenericParam *
 ASTLowerGenericParam::translate (AST::GenericParam &param)
 {
diff --git a/gcc/rust/hir/rust-ast-lower-type.h b/gcc/rust/hir/rust-ast-lower-type.h
index 2509276..1e88ec2 100644
--- a/gcc/rust/hir/rust-ast-lower-type.h
+++ b/gcc/rust/hir/rust-ast-lower-type.h
@@ -22,6 +22,7 @@
 #include "rust-ast-lower-base.h"
 #include "rust-ast-lower-expr.h"
 #include "rust-hir-path.h"
+#include "rust-type.h"
 
 namespace Rust {
 namespace HIR {
@@ -83,6 +84,7 @@ public:
   void visit (AST::NeverType &type) override;
   void visit (AST::TraitObjectTypeOneBound &type) override;
   void visit (AST::TraitObjectType &type) override;
+  void visit (AST::ParenthesisedType &type) override;
 
 private:
   ASTLoweringType (bool default_to_static_lifetime)