decl.c (gnat_to_gnu_entity): Make sure the size of a padding type built around…

decl.c (gnat_to_gnu_entity): Make sure the size of a padding type built around the return type is positive.

	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Function>: Make sure
	the size of a padding type built around the return type is positive.
	* gcc-interface/trans.c (gnat_to_gnu) <N_Simple_Return_Statement>:
	Use INIT_EXPR instead of MODIFY_EXPR to assign to the return object.

From-SVN: r224697

gcc/ada/ChangeLog

+2015-06-19  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Function>: Make sure
+	the size of a padding type built around the return type is positive.
+	* gcc-interface/trans.c (gnat_to_gnu) <N_Simple_Return_Statement>:
+	Use INIT_EXPR instead of MODIFY_EXPR to assign to the return object.
+
 2015-06-17  Andrew MacLeod  <amacleod@redhat.com>
 
 	* gcc-interface/cuintp.c: Do not include input.h, line-map.h or is-a.h.

gcc/ada/gcc-interface/decl.c

@@ -4242,12 +4242,23 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	    if (CONTAINS_PLACEHOLDER_P (TYPE_SIZE (gnu_return_type)))
 	      {
 		tree orig_type = gnu_return_type;
+		tree max_return_size
+		  = max_size (TYPE_SIZE (gnu_return_type), true);
+
+		/* If the size overflows to 0, set it to an arbitrary positive
+		   value so that assignments in the type are preserved.  Their
+		   actual size is independent of this positive value.  */
+		if (TREE_CODE (max_return_size) == INTEGER_CST
+		    && TREE_OVERFLOW (max_return_size)
+		    && integer_zerop (max_return_size))
+		  {
+		    max_return_size = copy_node (bitsize_unit_node);
+		    TREE_OVERFLOW (max_return_size) = 1;
+		  }
 
 		gnu_return_type
-		  = maybe_pad_type (gnu_return_type,
-				    max_size (TYPE_SIZE (gnu_return_type),
-					      true),
-				    0, gnat_entity, false, false, definition,
+		  = maybe_pad_type (gnu_return_type, max_return_size, 0,
+				    gnat_entity, false, false, definition,
 				    true);
 
 		/* Declare it now since it will never be declared otherwise.

gcc/ada/gcc-interface/trans.c

@@ -6861,7 +6861,7 @@ gnat_to_gnu (Node_Id gnat_node)
 		tree gnu_ret_deref
 		  = build_unary_op (INDIRECT_REF, TREE_TYPE (gnu_ret_val),
 				    gnu_ret_obj);
-		gnu_result = build2 (MODIFY_EXPR, void_type_node,
+		gnu_result = build2 (INIT_EXPR, void_type_node,
 				     gnu_ret_deref, gnu_ret_val);
 		add_stmt_with_node (gnu_result, gnat_node);
 		gnu_ret_val = NULL_TREE;