https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88342
--- Comment #2 from kargl at gcc dot gnu.org ---
(In reply to kargl from comment #1)
> (In reply to Matt Thompson from comment #0)
> > All,
> >
> > A colleague of mine encountered an issue with 8.2.0 (but it's also in 7.3.0
> > at least). We believe it might be a bug since our reading of the Standard
> > seems to make it legal.
> >
> > Namely if this program:
> >
> > PROGRAM test
> > USE, INTRINSIC :: ieee_arithmetic
> > IMPLICIT NONE
> > REAL :: inf
> > inf = IEEE_VALUE(inf, IEEE_POSITIVE_INF)
> > END PROGRAM test
> >
> > is compiled with -ffpe-trap=overflow the code FPEs:
>
> gfortran's IEEE modules and the -ffpe-trap option are independent
> of each other. As the manual states, -ffpe-trap is a *debugging*
> option, and will enabling traps on floating point exceptions. You
> specifically requested an overflow trap. What do you expect to
> happen?
>
> The likely correct solution is to manipulate the halting
> behavior with a combination of IEEE_GET_HALTING_MODE and
> IEEE_SET_HALTING_MODE. In fact, F2018, 17.11.6 contains
> this exact example.
>
> Example. To store the halting mode for IEEE_OVERFLOW, do a
> calculation without halting, and restore the halting mode later:
>
> USE, INTRINSIC :: IEEE_ARITHMETIC
> LOGICAL HALTING
> ...
> CALL IEEE_GET_HALTING_MODE (IEEE_OVERFLOW, HALTING) ! Store halting mode
> CALL IEEE_SET_HALTING_MODE (IEEE_OVERFLOW, .FALSE.) ! No halting
> ... ! calculation without halting
> CALL IEEE_SET_HALTING_MODE (IEEE_OVERFLOW, HALTING) ! Restore halting mode
>
> whether or not these functions works is something that I
> haven't investigated.
Just tested.
program test
use, intrinsic :: ieee_arithmetic
implicit none
real :: inf
logical h
call ieee_get_halting_mode(ieee_overflow, h) ! store halting mode
call ieee_set_halting_mode(ieee_overflow, .false.) ! no halting
inf = ieee_value(inf, ieee_positive_inf)
print *, inf
call ieee_set_halting_mode(ieee_overflow, h) ! restore halting mode
end program test
% gfcx -o z a.f90 && ./z
Infinity
% gfcx -o z -ffpe-trap=overflow a.f90 && ./z
Infinity
This seems to give the desired behavior.
