[C++ Patch/RFC] PR 55951

[Paolo Carlini]

Hi,

in mainline and 4.8, at variance with 4.7, for:
enum { A };

static const char *a[] = {
  [A] = "a"
};

check_array_designated_initializer is called by reshape_init* with 
ce->index a CONST_DECL, not an INTEGER_CST. Thus I wondered if in such 
cases it's just matter of using integral_constant_value on it, thus 
something like the below (which passes testing on x86_64-linux).

Thanks,
Paolo.

//////////////////////
Index: cp/decl.c
===================================================================
--- cp/decl.c   (revision 197097)
+++ cp/decl.c   (working copy)
@@ -4766,15 +4766,18 @@ check_array_designated_initializer (const construc
   /* Designated initializers for array elements are not supported.  */
   if (ce->index)
     {
+      tree ce_index = (TREE_CODE (ce->index) == CONST_DECL
+                      ? integral_constant_value (ce->index) : ce->index);
+
       /* The parser only allows identifiers as designated
         initializers.  */
       if (ce->index == error_mark_node)
        error ("name used in a GNU-style designated "
               "initializer for an array");
-      else if (TREE_CODE (ce->index) == INTEGER_CST)
+      else if (TREE_CODE (ce_index) == INTEGER_CST)
        {
          /* A C99 designator is OK if it matches the current index.  */
-         if (TREE_INT_CST_LOW (ce->index) == index)
+         if (TREE_INT_CST_LOW (ce_index) == index)
            return true;
          else
            sorry ("non-trivial designated initializers not supported");
Index: testsuite/g++.dg/ext/desig5.C
===================================================================
--- testsuite/g++.dg/ext/desig5.C       (revision 0)
+++ testsuite/g++.dg/ext/desig5.C       (working copy)
@@ -0,0 +1,7 @@
+// PR c++/55951
+
+enum { A };
+
+static const char *a[] = {
+  [A] = "a"
+};