gccrs: Implement lowering ReferencePattern from AST to HIR

gcc/rust/ChangeLog:

	* ast/rust-pattern.h:
	(ReferencePattern::is_double_reference): Add method.
	(ReferencePattern::get_is_mut): Add method.
	* hir/rust-ast-lower-pattern.cc
	(ASTLoweringPattern::visit): Add ReferencePattern visitor.
	* hir/rust-ast-lower-pattern.h:
	(ASTLoweringPattern::visit): Add ReferencePattern visitor.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>

gcc/rust/ast/rust-pattern.h

@@ -469,6 +469,10 @@ public:
     return pattern;
   }
 
+  bool is_double_reference () const { return has_two_amps; }
+
+  bool get_is_mut () const { return is_mut; }
+
   NodeId get_node_id () const { return node_id; }
 
   NodeId get_pattern_node_id () const override final { return node_id; }

gcc/rust/hir/rust-ast-lower-pattern.cc

@@ -249,5 +249,34 @@ ASTLoweringPattern::visit (AST::GroupedPattern &pattern)
   pattern.get_pattern_in_parens ()->accept_vis (*this);
 }
 
+void
+ASTLoweringPattern::visit (AST::ReferencePattern &pattern)
+{
+  auto crate_num = mappings->get_current_crate ();
+  Analysis::NodeMapping mapping (crate_num, pattern.get_node_id (),
+				 mappings->get_next_hir_id (crate_num),
+				 UNKNOWN_LOCAL_DEFID);
+
+  HIR::Pattern *inner
+    = ASTLoweringPattern::translate (pattern.get_referenced_pattern ().get ());
+
+  translated
+    = new HIR::ReferencePattern (mapping, std::unique_ptr<HIR::Pattern> (inner),
+				 pattern.get_is_mut () ? Mutability::Mut
+						       : Mutability::Imm,
+				 pattern.get_locus ());
+
+  if (pattern.is_double_reference ())
+    {
+      Analysis::NodeMapping mapping2 (crate_num, pattern.get_node_id (),
+				      mappings->get_next_hir_id (crate_num),
+				      UNKNOWN_LOCAL_DEFID);
+      translated
+	= new HIR::ReferencePattern (mapping2,
+				     std::unique_ptr<HIR::Pattern> (translated),
+				     Mutability::Imm, pattern.get_locus ());
+    }
+}
+
 } // namespace HIR
 } // namespace Rust

gcc/rust/hir/rust-ast-lower-pattern.h

@@ -40,6 +40,7 @@ public:
   void visit (AST::LiteralPattern &pattern) override;
   void visit (AST::RangePattern &pattern) override;
   void visit (AST::GroupedPattern &pattern) override;
+  void visit (AST::ReferencePattern &pattern) override;
 
 private:
   ASTLoweringPattern ();