[Ada] Fix ICE on renaming of 'Pred or 'Succ attribute

[Eric Botcazou]

This is a regression present on the mainline and 6 branch: the compiler stops 
on the renaming of the 'Pred or 'Succ attribute of a fixed-point type.

Tested on x86_64-suse-linux, applied on the mainline and 6 branch.


2016-06-13  Eric Botcazou  <ebotca...@adacore.com>

        * gcc-interface/decl.c (gnat_to_gnu_entity) <E_Variable>: Deal with
        PLUS_EXPR in the expression of a renaming.


2016-06-13  Eric Botcazou  <ebotca...@adacore.com>

        * gnat.dg/renaming10.ad[sb]: New test.

-- 
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c	(revision 237324)
+++ gcc-interface/decl.c	(working copy)
@@ -1003,6 +1003,7 @@ gnat_to_gnu_entity (Entity_Id gnat_entit
 		 && !call_is_atomic_load (inner))
 		|| TREE_CODE (inner) == ADDR_EXPR
 		|| TREE_CODE (inner) == NULL_EXPR
+		|| TREE_CODE (inner) == PLUS_EXPR
 		|| TREE_CODE (inner) == CONSTRUCTOR
 		|| CONSTANT_CLASS_P (inner)
 		/* We need to detect the case where a temporary is created to

package Renaming10 is

   type Rec is record
      Position : Natural;
   end record;

   function F (Input : Rec) return Natural;

end Renaming10;

-- { dg-do compile }

package body Renaming10 is

   function F (Input : Rec) return Natural is
      Position : Natural renames Input.Position;
      Index : Natural renames Natural'Succ(Position);
   begin
      return Index;
   end;

end Renaming10;