gccrs: Parse box expressions

Add support for old box expression syntax.

gcc/rust/ChangeLog:

	* ast/rust-ast-collector.cc (TokenCollector::visit): Add visit member
	function for BoxExpr nodes.
	* ast/rust-ast-collector.h: Add visit function prototype.
	* ast/rust-ast-visitor.cc (DefaultASTVisitor::visit): Add visit member
	function to default ast visitor.
	* ast/rust-ast-visitor.h: Add visit function's prototype.
	* ast/rust-ast.cc (BoxExpr::as_string): Add as_string function
	implementation for BoxExpr.
	(BoxExpr::accept_vis): Add accept_vis implementation to BoxExpr.
	* ast/rust-expr.h (class BoxExpr): Add BoxExpr class to represent boxed
	expressions.
	* expand/rust-derive.h: Add BoxExpr visit function prototype.
	* hir/rust-ast-lower-base.cc (ASTLoweringBase::visit): Add BoxExpr
	visitor implementation.
	* hir/rust-ast-lower-base.h: Add visit function's prototype.
	* hir/rust-ast-lower-expr.cc (ASTLoweringExpr::visit): Add BoxExpr
	visitor implementation.
	* hir/rust-ast-lower-expr.h: Add visit function's prototype.
	* parse/rust-parse-impl.h (Parser::parse_box_expr): Add parse_box_expr
	function's implementation.
	* parse/rust-parse.h: Add parse_box_expr function's prototype.
	* resolve/rust-ast-resolve-base.cc (ResolverBase::visit): Add resolver
	visit implementation.
	* resolve/rust-ast-resolve-base.h: Add resolver's visit function
	prototype.

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

2 files changed, 26 insertions, 0 deletions

diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h
index 9e186cc..d1f5b6b 100644
--- a/gcc/rust/parse/rust-parse-impl.h
+++ b/gcc/rust/parse/rust-parse-impl.h
@@ -7550,6 +7550,27 @@ Parser<ManagedTokenSource>::parse_literal_expr (AST::AttrVec outer_attrs)
 			  t->get_locus ()));
 }
 
+template <typename ManagedTokenSource>
+std::unique_ptr<AST::BoxExpr>
+Parser<ManagedTokenSource>::parse_box_expr (AST::AttrVec outer_attrs,
+					    location_t pratt_parsed_loc)
+{
+  location_t locus = pratt_parsed_loc;
+  if (locus == UNKNOWN_LOCATION)
+    {
+      locus = lexer.peek_token ()->get_locus ();
+      skip_token (BOX);
+    }
+
+  ParseRestrictions restrictions;
+  restrictions.expr_can_be_null = false;
+
+  std::unique_ptr<AST::Expr> expr = parse_expr (AST::AttrVec (), restrictions);
+
+  return std::unique_ptr<AST::BoxExpr> (
+    new AST::BoxExpr (std::move (expr), std::move (outer_attrs), locus));
+}
+
 // Parses a return expression (including any expression to return).
 template <typename ManagedTokenSource>
 std::unique_ptr<AST::ReturnExpr>
@@ -12461,6 +12482,8 @@ Parser<ManagedTokenSource>::null_denotation_not_path (
     case UNSAFE:
       return parse_unsafe_block_expr (std::move (outer_attrs),
 				      tok->get_locus ());
+    case BOX:
+      return parse_box_expr (std::move (outer_attrs), tok->get_locus ());
     case UNDERSCORE:
       add_error (
 	Error (tok->get_locus (),
diff --git a/gcc/rust/parse/rust-parse.h b/gcc/rust/parse/rust-parse.h
index c00bf9c..95c0a0b 100644
--- a/gcc/rust/parse/rust-parse.h
+++ b/gcc/rust/parse/rust-parse.h
@@ -622,6 +622,9 @@ private:
 							= AST::AttrVec ());
   AST::ClosureParam parse_closure_param ();
 
+  std::unique_ptr<AST::BoxExpr> parse_box_expr (AST::AttrVec outer_attrs,
+						location_t pratt_parsed_loc
+						= UNKNOWN_LOCATION);
   // When given a pratt_parsed_loc, use it as the location of the
   // first token parsed in the expression (the parsing of that first
   // token should be skipped).