[Bug libfortran/93727] Fortran 2018: EX edit descriptor

["thenlich at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93727

--- Comment #6 from Thomas Henlich <thenlich at gcc dot gnu.org> ---
(In reply to Jerry DeLisle from comment #5)
> I have been studying this a bit by looking at the 2023 std and functionality
> of printf().
> Specifically printf() provides the 'A' descriptor which can be used for
> float (kind=4) and double (kind=8).  It will accept a long double (80 bit
> aka kind=10). I am noticing that the results of double and long double are
> identical, no extra precision visible. It is very possible I am not doing
> that correctly.
> 
> I do not see anything related to quad precision floats.  I am posting this
> as i think we will have to do some of our own translating byte portions of
> floats ourselves. Portability may be an issue. For example IBM 360 128bit
> precision or some other processor may not follow the same internal
> representations.
> 
> Regardless I have preliminary code for the frontend that results in calling
> anew fucntion write_ex in transfer.c
> 
> I think that kind=4 and kind=8 will be fine. Any thoughts on kind=10 or
> kind=16 I would appreciate as I further explore this.

Just some thoughts:

Have you tried "%LA" for long double?

Have you tried quadmath_snprintf
(https://gcc.gnu.org/onlinedocs/libquadmath/quadmath_005fsnprintf.html) with
"%QA" for quad precision?