error: BB 13 can not throw but has EH edges

error: BB 13 can not throw but has EH edges

[Harald van Dijk]

Hi all,

I was trying to get a program running with GCC 4.3.0, which mostly
failed due to missing #include directives, but after a bit I ran into a
strange error, which I tried to reduce and got to the below:

struct GList {
  void *data;
  GList *next;
};
struct GtkWidget gtk_dialog_get_type();
typedef struct _GtkTreeIter GtkTreeIter;
struct GtkTreePath;
struct GtkTreeModel;
unsigned gtk_tree_model_get_type() __attribute__((__const__));
int gtk_tree_model_get_iter(GtkTreeModel *tree_model, GtkTreePath *);
GtkWidget *gtk_tree_view_new_with_model (GtkTreeModel *);
namespace std {
  namespace __gnu_cxx {
    template <typename _Tp> class new_allocator {};
  }
  template <typename _Tp> class allocator :
__gnu_cxx::new_allocator<_Tp> {
  public:
    template <typename _Tp1> struct rebind {
      typedef allocator<_Tp1> other;
    };
    ~allocator () {}
  };
  template <typename> class basic_string;
  typedef basic_string<char> string;
  template <typename _Tp> struct _List_node;
  template <typename _Tp, typename _Alloc> class _List_base {
    typedef typename _Alloc::template rebind<_List_node<_Tp> >::other
_Node_alloc_type;
    _Node_alloc_type _M_impl;
  };
  template <typename _Tp, typename _Alloc = std::allocator<_Tp> > class
list : _List_base <_Tp, _Alloc> {};
}
class DictManageDlg {
  void show_add_dict_dialog (GtkTreeIter *);
};
void DictManageDlg::show_add_dict_dialog (GtkTreeIter *)
{
  std::list<std::string> added_dictlist;
  gtk_tree_view_new_with_model((GtkTreeModel *)
gtk_tree_model_get_type());
  {
    GList *selectlist;
    if (selectlist) {
      GList *list = selectlist;
      while (list) {
        gtk_tree_model_get_iter((GtkTreeModel *)
gtk_tree_model_get_type(), (GtkTreePath *) list->data);
        list = list->next;
      }
    }
  }
}

Apologies for the relatively long testcase, but I couldn't significantly
reduce it further. When compiling this with 'gcc -c -O bug.ii', I get:

bug.ii: In member function ‘void
DictManageDlg::show_add_dict_dialog(GtkTreeIter*)’:
bug.ii:35: error: BB 13 can not throw but has EH edges
bug.ii:35: internal compiler error: verify_flow_info failed
Please submit a full bug report,

I first ran into this with Gentoo's GCC 4.3.0, but I made sure to test
without any patches, and built official GCC configured with

../gcc-4.3.0/configure --prefix=$HOME/gcc --enable-languages=c,c++ \
	--enable-checking --build=i686-pc-linux-gnu

Now, I have a few questions:

- Is this a known issue? I've searched for this error, but only got
results requiring specific compiler options that aren't necessary to get
it to fail here. I will report it as a bug if it's not known (and not
already fixed by accident).

- When I disable checking, GCC does not generate any error message. Can
I expect that the code it generates will be correct, or might it be
broken and going undetected?

- What would you recommend as a workaround (other than disabling
checking)? My first guess would be to remove __attribute__((__const__)), but
that's not an option, as it's part of gtk, and not of the program
itself. Do you have a good alternative?

Re: error: BB 13 can not throw but has EH edges

[Brian Dessent]

Harald van D?k wrote:

> - Is this a known issue? I've searched for this error, but only got
> results requiring specific compiler options that aren't necessary to get
> it to fail here. I will report it as a bug if it's not known (and not
> already fixed by accident).

This looks like <http://gcc.gnu.org/PR35261>.

> - When I disable checking, GCC does not generate any error message. Can
> I expect that the code it generates will be correct, or might it be
> broken and going undetected?

Disabling checking just papers over the real problem, which is an
internal inconsistency in gcc.  Whether or not the generated code is
correct is unknown.

> - What would you recommend as a workaround (other than disabling
> checking)? My first guess would be to remove __attribute__((__const__)), but
> that's not an option, as it's part of gtk, and not of the program
> itself. Do you have a good alternative?

I'd add your testcase to that PR above, at least.  You could also try
the current trunk and see if it's fixed there.

Brian

Re: error: BB 13 can not throw but has EH edges

[Harald van Dijk]

On Mon, Apr 14, 2008 at 09:21:47PM -0700, Brian Dessent wrote:
> Harald van D?k wrote:
> 
> > - Is this a known issue? I've searched for this error, but only got
> > results requiring specific compiler options that aren't necessary to get
> > it to fail here. I will report it as a bug if it's not known (and not
> > already fixed by accident).
> 
> This looks like <http://gcc.gnu.org/PR35261>.
> 
> > - When I disable checking, GCC does not generate any error message. Can
> > I expect that the code it generates will be correct, or might it be
> > broken and going undetected?
> 
> Disabling checking just papers over the real problem, which is an
> internal inconsistency in gcc.  Whether or not the generated code is
> correct is unknown.

Yes, and that was what I was curious about: I was wondering whether the
optimiser is incorrect, or only the checks. If it turns out the checks
are incorrect, there's no reason for me to doubt the rest, but I'm not
at all familiar enough with GCC's structure to see what's going on.

> > - What would you recommend as a workaround (other than disabling
> > checking)? My first guess would be to remove __attribute__((__const__)), but
> > that's not an option, as it's part of gtk, and not of the program
> > itself. Do you have a good alternative?
> 
> I'd add your testcase to that PR above, at least.  You could also try
> the current trunk and see if it's fixed there.

Thanks, I've tried the most recent snapshots of 4.3 and 4.4, but they
both fail the same way. I've attached a testcase that's a bit shorter to
the bug.