[Bug c++/53094] constexpr vector subscripting

["vincenzo.innocente at cern dot ch" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53094

--- Comment #11 from vincenzo Innocente <vincenzo.innocente at cern dot ch> 2012-12-03 21:58:05 UTC ---
thanks Marc,
adding your proposed change above Jason's one make my full test works (but when
subscripting is involved..)
this is my current svn diff
Hope that c++ maintainers came make, out of all this, an optimal patch for the
trunk. 
I'm not expert enough on the details to judge what best (besides that I did not
run regression!)

Index: gcc/cp/tree.c
===================================================================
--- gcc/cp/tree.c    (revision 194084)
+++ gcc/cp/tree.c    (working copy)
@@ -2468,7 +2468,8 @@
     case COMPLEX_CST:
       return cp_tree_equal (TREE_REALPART (t1), TREE_REALPART (t2))
     && cp_tree_equal (TREE_IMAGPART (t1), TREE_IMAGPART (t2));
-
+    case VECTOR_CST:
+          return operand_equal_p (t1, t2, OEP_ONLY_CONST);    
     case CONSTRUCTOR:
       /* We need to do this when determining whether or not two
      non-type pointer to member function template arguments
Index: gcc/cp/semantics.c
===================================================================
--- gcc/cp/semantics.c    (revision 194084)
+++ gcc/cp/semantics.c    (working copy)
@@ -6451,6 +6451,14 @@
   /* Avoid wrapping an aggregate value in a NOP_EXPR.  */
   if (TREE_CODE (temp) == CONSTRUCTOR)
     return build_constructor (type, CONSTRUCTOR_ELTS (temp));
+  if (TREE_CODE (temp) == VECTOR_CST)
+    {
+      int i, count = TYPE_VECTOR_SUBPARTS (type);
+      tree *vec = XALLOCAVEC (tree, count);
+      for (i = 0; i < count; i++)
+    vec[i] = cp_fold_convert (TREE_TYPE (type), VECTOR_CST_ELT (temp, i));
+      return build_vector (type, vec);
+    }
   gcc_assert (SCALAR_TYPE_P (type));
   return cp_fold_convert (type, temp);
 }
@@ -7134,7 +7142,10 @@
       vec_free (n);
       return t;
     }
+
   t = build_constructor (TREE_TYPE (t), n);
+  if (TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
+    t = fold (t);
   TREE_CONSTANT (t) = true;
   return t;
 }