Hello,

I'm currently working on migrating debugging information for Ada from 
GNAT encodings to standard DWARF. At the moment, I have worked on two 
topics that I believe are not (completely) supported in standard DWARF:

   - fixed point types with arbitrary scale factors;
   - scalar types with biased representations.

My goal is to submit an issue on dwarfstd.org in an attempt to introduce 
these extensions to the next DWARF standard. Before that, though, I 
would like to make sure that these extensions actually fit the need by 
having them supported both in GCC and GDB.

The two attached patches make these extensions "public" so that no other 
vendor-specific tags/attributes conflict with them in the future. I 
cannot submit the patches that actually use these right now because I 
need first to port them from the 4.9 branch onto mainline (I hope I will 
be able to do this on early July).

May I commit them?

I also attached two documents that describe how to use these 
extensions. I guess this should go to the wiki just like for 
DW_AT_GNAT_descriptive_type 
(https://gcc.gnu.org/wiki/DW_AT_GNAT_descriptive_type). I will do this 
if the patches are integrated.

Thank you in advance!

include/
         * dwarf2.def (DW_TAG_GNU_rational_constant): New tag.
         (DW_AT_GNU_numerator, DW_AT_GNU_denominator): New attributes.

include/
         * dwarf2.def (DW_AT_GNU_bias): New attribute.

-- 
Pierre-Marie de Rodat