[RFC] DW_AT_type missing from DW_TAG_subrange_type

[Denis PILAT <denis dot pilat at st dot com>]

For the global variable declared like that
 int array[] = {1, 2, 3, 4};
the dwarf information generated by our specific compiler is missing 
DW_AT_type missing from DW_TAG_subrange_type.

Usually in dwarf2 information (ie like the bellow example for gcc4 under 
linux), the DW_AT_type exists for subranges :

  < 175 (0xaf) > DW_TAG_array_type
  | DW_AT_sibling : < 191 (0xbf) >
  | DW_AT_type : < 168 (0xa8) >
  `--------------------------
     < 184 (0xb8) > DW_TAG_subrange_type
   * | DW_AT_type : < 191 (0xbf) >*          <<<<<-------- missing from 
my elf file
     | DW_AT_upper_bound : DW_AT_upper_bound(DW_FORM_data1) : 3
     `--------------------------


Therefore we go thru the code "base_type = alloc_type (NULL)" (in 
read_subrange_type of dwarf2read.c) and gdb prints the following if "set 
print array-indexes on": (all indexes are set to 0):
(gdb) p array
$1 = {[0] = 1, [0] = 2, [0] = 3, [0] = 4}

Could we have a *builtin_type_int* as the default type instead of 
alloc_type (NULL) ?
*Attach is a patch in that sense.*



I'm also wondering about  the code:
 base_type = die_type (die, cu);
 if (base_type == NULL)
   {
     complaint (&symfile_complaints,
               _("DW_AT_type missing from DW_TAG_subrange_type"));
     return;
   }
It seems we'll never have (base_type == NULL). Am I right ?
May be it's time to remove that as well. The complaints seems to be in a 
better place in my patch.


For information, this testcase is present in gdb.base/arrayidx.exp where 
we have "set print array-indexes on"

No regression for this patch for i386-linux target

--
Denis



Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.216
diff -u -p -r1.216 dwarf2read.c
--- dwarf2read.c        30 Mar 2007 17:21:47 -0000      1.216
+++ dwarf2read.c        3 Apr 2007 09:41:07 -0000
@@ -4921,7 +4921,11 @@ read_subrange_type (struct die_info *die
    }

  if (TYPE_CODE (base_type) == TYPE_CODE_VOID)
-    base_type = alloc_type (NULL);
+    {
+      complaint (&symfile_complaints,
+                _("DW_AT_type missing from DW_TAG_subrange_type"));
+      base_type = builtin_type_int;
+    }

  if (cu->language == language_fortran)
    {