[Bug debug/48229] DW_TAG_type_unit has no DW_AT_producer

["jan.kratochvil at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48229

--- Comment #4 from Jan Kratochvil <jan.kratochvil at redhat dot com> 2011-03-23 13:07:02 UTC ---
(In reply to comment #3)
> I think it is a bad idea to add DW_AT_producer to .debug_type units.  Making
> each .debug_types addition 4 bytes longer is bad for debug info size, we might
> have many thousands DW_TAG_type_units for each source.
> I think you can safely use referring DW_TAG_compile_unit's DW_AT_producer for
> your purposes.  While it is true that .debug_types sections in the end comes
> from different *.o file and be produced by different compiler, it will be
> referenced by the current CU only if it hashes the same, thus has the same
> content (disregarding hash collisions, in which case you are in very bad
> trouble, but you are in that very bad trouble no matter whether you just
> want to make sure it was produced by the same or compatible producer - when
> hash collision happens, it might refer to completely unrelated type).

I guess there cannot be two struct/class definitions with different fields
accessibility accidentally matching each other due to ODR.

Still I believe DW_TAG_type_unit should have DW_AT_producer as it is a
standalone entity - but currently it is not.  I guess I have to implement your
described althorithm into GDB instead.  Dodji, thanks and sorry for the patch.