https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64958
--- Comment #3 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
If it is forbidden to modify an actual argument, we could make
a tempoary copy of that argument, pass that to a procedure where
it maches an intent(unknown) dummy argument, then do the comparison.
So, we would replace
subroutine bar(n)
integer, intent(in) :: n
call dusty(n)
end subroutine bar
with
subroutine bar(n)
integer, intent(in) :: n
integer :: shadow_n
shadow_n = n
call dusty(shadow_n)
if (n /= shadow_n) call _gfortran_runtime_error("bletchful")
end subroutine bar
where dusty has no explicit interface or the first dummy argument
of dusty has unknown intent.
It would probably make most sense for scalar intrinsic types inculding
character variables. Arrays of intrinsic types might also be a possibility,
but with decreasing return on investment, so to speak.
