[Bug fortran/84389] New: Defined output: unexpected compiler error with the use of ":" edit descriptor

["fortranfan at outlook dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84389

            Bug ID: 84389
           Summary: Defined output: unexpected compiler error with the use
                    of ":" edit descriptor
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fortranfan at outlook dot com
  Target Milestone: ---

Consider the following:

--- begin console output ---
C:\Temp>type p.f90
module m

   type :: t
      private
   contains
      private
      procedure, pass(this) :: write_t
      generic, public :: write(formatted) => write_t
   end type

contains

   subroutine write_t(this, lun, iotype, vlist, istat, imsg)

      ! argument definitions
      class(t), intent(in)            :: this
      integer, intent(in)             :: lun
      character(len=*), intent(in)    :: iotype
      integer, intent(in)             :: vlist(:)
      integer, intent(out)            :: istat
      character(len=*), intent(inout) :: imsg

      write(lun, fmt=*, iostat=istat, iomsg=imsg) "Hello World!"

      return

   end subroutine write_t

end module

program p

   use m, only : t

   type(t) :: foo(2)

   print "(*(dt:,','))", foo

end program

C:\Temp>gfortran p.f90 -o p.exe
p.f90:37:14:

    print "(*(dt:,','))", foo
              1
Error: Unexpected element ':' in format string at (1)

C:\Temp>
--- end output ---

Program compiled and built using another toolset gives my expected output:
Hello World!,Hello World!


Cheers,