[C++ Patch] Minor cxx_eval_constant_expression clean-up

[Paolo Carlini]

Hi,

I was having a look to c++/52282 and noticed the this code can be tidied 
a little bit (similarly to case ADDR_EXPR). Patch tested x86_64-linux.

Ok?

Thanks,
Paolo.

/////////////////////
2012-05-04  Paolo Carlini  <paolo.carl...@oracle.com>

        * semantics.c (cxx_eval_constant_expression, case CONVERT_EXPR): Tidy.

Index: semantics.c
===================================================================
--- semantics.c (revision 187162)
+++ semantics.c (working copy)
@@ -7757,18 +7757,16 @@ cxx_eval_constant_expression (const constexpr_call
     case NOP_EXPR:
       {
        tree oldop = TREE_OPERAND (t, 0);
-       tree op = oldop;
-       tree to = TREE_TYPE (t);
-       op = cxx_eval_constant_expression (call, TREE_OPERAND (t, 0),
-                                          allow_non_constant, addr,
-                                          non_constant_p);
+       tree op = cxx_eval_constant_expression (call, oldop,
+                                               allow_non_constant, addr,
+                                               non_constant_p);
        if (*non_constant_p)
          return t;
        if (op == oldop)
          /* We didn't fold at the top so we could check for ptr-int
             conversion.  */
          return fold (t);
-       r = fold_build1 (TREE_CODE (t), to, op);
+       r = fold_build1 (TREE_CODE (t), TREE_TYPE (t), op);
        /* Conversion of an out-of-range value has implementation-defined
           behavior; the language considers it different from arithmetic
           overflow, which is undefined.  */