>> That will do, although I think there might be a bug there :(. Let me 
>> double check.
>>     
>
> There is certainly a bug hit by Stan's test case, since it gets an error.
>   
So yes there is a bug, I have not checked to see if it is Stan's bug, 
but here it goes:

This is the test case that I am using:

inline void second(){
  int* a = 0;
  a[0] = 0;          <-------- pc
}

void first(){
  second();
}

int main(){
  first();
  return 0;
}

So if I try to dwarf_getscopes at pc i get 0 scopes returned. The 
problem is in the pc_record function from dwarf_getscopes.c:

>  /* Now we are in a scope that contains the concrete inlined instance.
>     Search it for the inline function's abstract definition.
>     If we don't find it, return to search the containing scope.
>     If we do find it, the nonzero return value will bail us out
>     of the postorder traversal.  */
>  return __libdw_visit_scopes (depth, die, &origin_match, NULL, &a);
> }
The problem is that if the die passed to __libdw_visit_scopes has no 
children, __libdw_visit_scopes returns -1 which means that pc_record 
returns -1 and the search aborts, and no scopes are returned.

The particular childless die in this case happens to be the one 
corresponding to main. I can fudge it by adding some variables to main 
and get the following scopes:

scopes[0] DW_TAG_lexical_block name:
scopes[1] DW_TAG_inlined_subroutine name: second
scopes[2] DW_TAG_compile_unit name: 
/to/scratch/swagiaal/frysks/frysk/frysk-core/frysk/pkglibdir/funit-scopes.c

I have attached two of possible patches:

patch1 just check for children before the call, patch2 takes the 
responsibility away from pc_record and relies on the later call to 
pc_origin in dwarf_getscopes:

[...]
int result = __libdw_visit_scopes (0, &cu, &pc_match, &pc_record, &a);

if (result == 0 && a.scopes != NULL)
  result = __libdw_visit_scopes (0, &cu, &origin_match, NULL, &a);
[...]

I personally like patch2 better. This way you only do two searches.

Thoughts ?

Thanks,
  Sami Wagiaalla