On Wed, Sep 11, 2019 at 11:27:56PM +0100, Paul Richard Thomas wrote:
> Hi Steve,
>
> Being an allocatable component, this code appears on entry into scope:
>
> my_core.msg = 0B;
> my_core._msg_length = 0;
> {
>
> Thus, according to the standard, my_core%msg is defined.
>
I'll politely defer to the Fortran standard.
5.4.10 Allocatable variables
The allocation status of an allocatable variable is either allocated
or unallocated. An allocatable variable becomes allocated as described
in 9.7.1.3. It becomes unallocated as described in 9.7.3.2.
An unallocated allocatable variable shall not be referenced or defined.
7.5.4.6 Default initialization for components
Allocatable components are always initialized to unallocated.
In your testcase, you have an unallocatable allocatable entity
referenced on the RHS in the first line that involves my_core%msg.
>From the Fortran standard's point of view, I believe the code is
nonconforming.
type core
character (len=:), allocatable :: msg
end type
type(core) :: my_core
print *, allocated(my_core%msg)
! Comment out to avoid ICE.
! my_core%msg on RHS is unallocated in next line.
! my_core%msg = my_core%msg//"my message is:
! my_core%msg = my_core%msg//"Hello!"
!
! if (my_core%msg .ne. "my message is: Hello!") stop 1
end
% gfcx -o z a.f90 && ./z
F
> detected for this assignment even though no array references are
> involved. There is certainly the need for a temporary, which the patch
> generates.
>
Your patch may fix the ICE, but if the code compiles and
execute. You are getting the "right" answer fortuitiouly.
Of course, I could be wrong.
--
Steve
