Re: Why is the TREE_PURPOSE of a CONSTRUCTOR_ELT list forARRAY_TYPE NULL?

[Daniel Berlin <dberlin at dberlin dot org>]

On Mon, 2004-09-06 at 21:19 -0400, Richard Kenner wrote:
>     Then a sanity check should really be added somewhere, when the FE is
>     fixed.  During gimplification maybe?
> 
> There is one, in gimplify_init_ctor_eval:
> 
> 	  /* ??? Here's to hoping the front end fills in all of the indicies,
> 	     so we don't have to figure out what's missing ourselves.  */
> 	  if (!purpose)
> 	    abort ();
> 
> I don't know why it wasn't triggered in this case.
The thing in question was a readonly static.
Maybe this is why (I thought we kept DECL_INITIAL for those, instead of
gimplifying it)?  I'm just taking a shot in the dark
The testcase is actually rather short.
I've pasted it below, and i'll file a bug report with it.
(gdb) p debug_tree (decl)
 <var_decl 0x40139414 _ZTVSt9exception
    type <array_type 0x401396cc
....

(gdb) p debug_tree (decl.decl.initial)
 <constructor 0x4005bb80
    arg 0 <tree_list 0x401383c0
        value <nop_expr 0x4005bac0 type <pointer_type 0x400cec3c
__vtbl_ptr_type>
            constant invariant
            arg 0 <integer_cst 0x40138348 constant invariant 0>>
        chain <tree_list 0x401383a8
            value <nop_expr 0x4005baa0 type <pointer_type 0x400cec3c
__vtbl_ptr_type>
                readonly constant invariant
....
(note the lack of purpose trees)

simple testcase:

extern "C++"
{
  namespace std
  {
    class exception
    {
    public:exception () throw ()
      {
      } virtual ~ exception () throw ();
      virtual const char *what () const throw ();
    };
  }
  namespace __cxxabiv1
  {
  }
  namespace std
  {
    class bad_cast:public exception
    {
    public:bad_cast () throw ()
      {
      } virtual ~ bad_cast () throw ();
    };
  }
}
namespace __cxxabiv1
{
  extern "C" void __cxa_bad_cast ();
}
extern "C" void
__cxxabiv1::__cxa_bad_cast ()
{
  throw std::bad_cast ();
}