re PR bootstrap/68346 (Bootstrap failure on i686-linux)

	PR bootstrap/68346

	* typeck.c (build_static_cast_1): Force a NOP when converting to
	the same type.

From-SVN: r230508

gcc/cp/ChangeLog

 2015-11-17  Jason Merrill  <jason@redhat.com>
 
+	PR bootstrap/68346
+	* typeck.c (build_static_cast_1): Force a NOP when converting to
+	the same type.
+
 	* cp-tree.h (LITERAL_ZERO_P): Remove.
 	* parser.c (cp_parser_postfix_expression, literal_zeros)
 	(cp_parser_parenthesized_expression_list): Don't mess with it.

gcc/cp/typeck.c

@@ -6668,7 +6668,13 @@ build_static_cast_1 (tree type, tree expr, bool c_cast_p,
 	 If T is a reference type, the result is an lvalue; otherwise,
 	 the result is an rvalue.  */
       if (TREE_CODE (type) != REFERENCE_TYPE)
-	result = rvalue (result);
+	{
+	  result = rvalue (result);
+
+	  if (result == expr && SCALAR_TYPE_P (type))
+	    /* Leave some record of the cast.  */
+	    result = build_nop (type, expr);
+	}
       return result;
     }