Re: [C++ Patch] PR 14710 (add -Wuseless-cast)

[Jason Merrill]

On 03/18/2012 11:32 AM, Paolo Carlini wrote:

+      if ((TREE_CODE (type) == REFERENCE_TYPE
+       &&  lvalue_p (expr)
+       &&  same_type_p (TREE_TYPE (expr), TREE_TYPE (type)))
+         || same_type_p (TREE_TYPE (expr), type))
+       warning (OPT_Wuseless_cast, "useless cast to type %qT", type);

I think instead of just lvalue_p (expr) you want

  TYPE_REF_IS_RVALUE (type) ? xvalue_p (expr) : real_lvalue_p (expr)

where xvalue_p is a new function that just does

  return lvalue_kind (expr) == clk_rvalueref;

Jason