ABI breakages in 4.4

[Jerry DeLisle]

Richard Guenther wrote:
> On Sat, Sep 13, 2008 at 5:00 PM, Tobias Burnus <burnus@net-b.de> wrote:
>> Thomas Koenig wrote:
>>>> just a heads-up: we have a couple of ABI breakages where 4.3-compiled
>>>> programs don't work correctly with the 4.4 library, namely PR 37498
>> The problem is that the struct passed for I/O has been modified to allow
>> Fortran 2003 features (UTF-8, rounding, decimal comma etc.). The problem
>> is that in libgfortran the new struct is expected, but gfortran 4.3
>> programs only passes a shorter struct. In the PR this causes that values
>> in an unrelated array are overwritten.
>>
>> Do you have an idea how this should be solved?
>>

Move the F2003 related items inside st_parameter_dt.u.p where we already have 
the padding.  We may have to expand the padding.  We then have to adjust the 
front end where we build these structures.  Essentially the top half of 
st_parameter.dt will then match exactly 4.3 again.

Another option us to move the items to just after the union.  The items in 
question are:

   GFC_IO_INT *id;
   GFC_IO_INT pos;
   CHARACTER1 (asynchronous);
   CHARACTER2 (blank);
   CHARACTER1 (decimal);
   CHARACTER2 (delim);
   CHARACTER1 (pad);
   CHARACTER2 (round);
   CHARACTER1 (sign);


Does this sound workable?

On the library side the changes are fairly mechanical.  I will need help with 
the frontend parts.

Jerry