Prevent raw reference from being lowered silently

We do not handle those kind of references yet, we shall not let them
pass as a regular reference.

gcc/rust/ChangeLog:

	* ast/rust-expr.h: Add a getter for mutability.
	* hir/rust-ast-lower-expr.cc (ASTLoweringExpr::visit): Panic when a
	raw reference is met.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

2 files changed, 9 insertions, 6 deletions

diff --git a/gcc/rust/ast/rust-expr.h b/gcc/rust/ast/rust-expr.h
index 6609ad8..a5afbff 100644
--- a/gcc/rust/ast/rust-expr.h
+++ b/gcc/rust/ast/rust-expr.h
@@ -398,6 +398,8 @@ public:
 
   bool get_is_mut () const { return mutability == Mutability::Mut; }
 
+  Mutability get_mutability () const { return mutability; }
+
   bool get_is_double_borrow () const { return double_borrow; }
   bool is_raw_borrow () const { return raw_borrow; }
 
diff --git a/gcc/rust/hir/rust-ast-lower-expr.cc b/gcc/rust/hir/rust-ast-lower-expr.cc
index 3b462ee..063a5fb 100644
--- a/gcc/rust/hir/rust-ast-lower-expr.cc
+++ b/gcc/rust/hir/rust-ast-lower-expr.cc
@@ -628,6 +628,9 @@ ASTLoweringExpr::visit (AST::ContinueExpr &expr)
 void
 ASTLoweringExpr::visit (AST::BorrowExpr &expr)
 {
+  if (expr.is_raw_borrow ())
+    rust_unreachable ();
+
   HIR::Expr *borrow_lvalue
     = ASTLoweringExpr::translate (expr.get_borrowed_expr ());
 
@@ -638,9 +641,8 @@ ASTLoweringExpr::visit (AST::BorrowExpr &expr)
 
   auto *borrow_expr
     = new HIR::BorrowExpr (mapping, std::unique_ptr<HIR::Expr> (borrow_lvalue),
-			   expr.get_is_mut () ? Mutability::Mut
-					      : Mutability::Imm,
-			   expr.get_outer_attrs (), expr.get_locus ());
+			   expr.get_mutability (), expr.get_outer_attrs (),
+			   expr.get_locus ());
 
   if (expr.get_is_double_borrow ())
     {
@@ -652,9 +654,8 @@ ASTLoweringExpr::visit (AST::BorrowExpr &expr)
       borrow_expr
 	= new HIR::BorrowExpr (mapping,
 			       std::unique_ptr<HIR::Expr> (borrow_expr),
-			       expr.get_is_mut () ? Mutability::Mut
-						  : Mutability::Imm,
-			       expr.get_outer_attrs (), expr.get_locus ());
+			       expr.get_mutability (), expr.get_outer_attrs (),
+			       expr.get_locus ());
     }
 
   translated = borrow_expr;