fix darwin bootstrap by avoiding duplicate DIE attributes

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index ee2bcb1..9a95ba0 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -3089,7 +3089,7 @@  static void add_AT_offset (dw_die_ref, enum dwarf_attribute,
 static void add_AT_range_list (dw_die_ref, enum dwarf_attribute,
                                unsigned long, bool);
 static inline const char *AT_lbl (dw_attr_ref);
-static dw_attr_ref get_AT (dw_die_ref, enum dwarf_attribute);
+static dw_attr_ref get_AT (dw_die_ref, enum dwarf_attribute, bool follow = true);
 static const char *get_AT_low_pc (dw_die_ref);
 static const char *get_AT_hi_pc (dw_die_ref);
 static const char *get_AT_string (dw_die_ref, enum dwarf_attribute);
@@ -4579,10 +4579,14 @@  AT_lbl (dw_attr_ref a)
   return a->dw_attr_val.v.val_lbl_id;
 }
 
-/* Get the attribute of type attr_kind.  */
+/* Get the attribute of type attr_kind.
+
+   FOLLOW is true if we should drill down through DW_AT_specification
+   and DW_AT_abstract_origin attributes.  */
 
 static dw_attr_ref
-get_AT (dw_die_ref die, enum dwarf_attribute attr_kind)
+get_AT (dw_die_ref die, enum dwarf_attribute attr_kind,
+	bool follow /*= true*/)
 {
   dw_attr_ref a;
   unsigned ix;
@@ -4594,8 +4598,8 @@  get_AT (dw_die_ref die, enum dwarf_attribute attr_kind)
   FOR_EACH_VEC_SAFE_ELT (die->die_attr, ix, a)
     if (a->dw_attr == attr_kind)
       return a;
-    else if (a->dw_attr == DW_AT_specification
-	     || a->dw_attr == DW_AT_abstract_origin)
+    else if (follow && (a->dw_attr == DW_AT_specification
+			|| a->dw_attr == DW_AT_abstract_origin))
       spec = AT_ref (a);
 
   if (spec)
@@ -5690,20 +5694,55 @@  debug_dwarf (void)
 static void
 check_die (dw_die_ref die)
 {
-  /* A debugging information entry that is a member of an abstract
-     instance tree [that has DW_AT_inline] should not contain any
-     attributes which describe aspects of the subroutine which vary
-     between distinct inlined expansions or distinct out-of-line
-     expansions.  */
   unsigned ix;
   dw_attr_ref a;
   bool inline_found = false;
+  int n_location = 0, n_low_pc = 0, n_high_pc = 0, n_artificial = 0;
+  int n_decl_line = 0, n_decl_file = 0;
   FOR_EACH_VEC_SAFE_ELT (die->die_attr, ix, a)
-    if (a->dw_attr == DW_AT_inline && a->dw_attr_val.v.val_unsigned)
-      inline_found = true;
+    {
+      switch (a->dw_attr)
+	{
+	case DW_AT_inline:
+	  if (a->dw_attr_val.v.val_unsigned)
+	    inline_found = true;
+	  break;
+	case DW_AT_location:
+	  ++n_location;
+	  break;
+	case DW_AT_low_pc:
+	  ++n_low_pc;
+	  break;
+	case DW_AT_high_pc:
+	  ++n_high_pc;
+	  break;
+	case DW_AT_artificial:
+	  ++n_artificial;
+	  break;
+	case DW_AT_decl_line:
+	  ++n_decl_line;
+	  break;
+	case DW_AT_decl_file:
+	  ++n_decl_file;
+	  break;
+	default:
+	  break;
+	}
+    }
+  if (n_location > 1 || n_low_pc > 1 || n_high_pc > 1 || n_artificial > 1
+      || n_decl_line > 1 || n_decl_file > 1)
+    {
+      fprintf (stderr, "Duplicate attributes in DIE:\n");
+      debug_dwarf_die (die);
+      gcc_unreachable ();
+    }
   if (inline_found)
     {
-      /* Catch the most common mistakes.  */
+      /* A debugging information entry that is a member of an abstract
+	 instance tree [that has DW_AT_inline] should not contain any
+	 attributes which describe aspects of the subroutine which vary
+	 between distinct inlined expansions or distinct out-of-line
+	 expansions.  */
       FOR_EACH_VEC_SAFE_ELT (die->die_attr, ix, a)
 	gcc_assert (a->dw_attr != DW_AT_low_pc
 		    && a->dw_attr != DW_AT_high_pc
@@ -16095,6 +16134,9 @@  add_location_or_const_value_attribute (dw_die_ref die, tree decl, bool cache_p,
   if (TREE_CODE (decl) == ERROR_MARK)
     return false;
 
+  if (get_AT (die, attr, /*follow=*/false))
+    return true;
+
   gcc_assert (TREE_CODE (decl) == VAR_DECL || TREE_CODE (decl) == PARM_DECL
 	      || TREE_CODE (decl) == RESULT_DECL);
 
@@ -18055,10 +18097,9 @@  gen_formal_parameter_die (tree node, tree origin, bool emit_name_p,
 				decl_quals (node_or_origin),
 				context_die);
 	}
-    add_location:
       if (origin == NULL && DECL_ARTIFICIAL (node))
 	add_AT_flag (parm_die, DW_AT_artificial, 1);
-
+    add_location:
       if (node && node != origin)
         equate_decl_number_to_die (node, parm_die);
       if (! DECL_ABSTRACT_P (node_or_origin))
@@ -20354,15 +20395,19 @@  static void
 gen_struct_or_union_type_die (tree type, dw_die_ref context_die,
 				enum debug_info_usage usage)
 {
-  /* Fill in the bound of variable-length fields in late dwarf if
-     still incomplete.  */
-  if (TREE_ASM_WRITTEN (type)
-      && variably_modified_type_p (type, NULL)
-      && !early_dwarf)
+  if (TREE_ASM_WRITTEN (type))
     {
-      tree member;
-      for (member = TYPE_FIELDS (type); member; member = DECL_CHAIN (member))
-	fill_variable_array_bounds (TREE_TYPE (member));
+      /* Fill in the bound of variable-length fields in late dwarf if
+	 still incomplete.  */
+      if (variably_modified_type_p (type, NULL)
+	  && !early_dwarf)
+	{
+	  tree member;
+	  for (member = TYPE_FIELDS (type);
+	       member;
+	       member = DECL_CHAIN (member))
+	    fill_variable_array_bounds (TREE_TYPE (member));
+	}
       return;
     }
 
@@ -20842,7 +20887,13 @@  gen_type_die_with_usage (tree type, dw_die_ref context_die,
 static void
 gen_type_die (tree type, dw_die_ref context_die)
 {
-  gen_type_die_with_usage (type, context_die, DINFO_USAGE_DIR_USE);
+  if (type != error_mark_node)
+    {
+      gen_type_die_with_usage (type, context_die, DINFO_USAGE_DIR_USE);
+      dw_die_ref die = lookup_type_die (type);
+      if (die)
+	check_die (die);
+    }
 }
 
 /* Generate a DW_TAG_lexical_block DIE followed by DIEs to represent all of the