[Bug fortran/98686] New: Namelist group objects shall be defined before appearing in namelist for -std=f2018

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98686

            Bug ID: 98686
           Summary: Namelist group objects shall be defined before
                    appearing in namelist for -std=f2018
           Product: gcc
           Version: fortran-dev
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: anlauf at gcc dot gnu.org
  Target Milestone: ---

The following code is silently accepted even with -std=f95 ... -std=2018:

  implicit none
  namelist /NML/ x, m, q
  real    :: x, m
  integer :: q
  x = 1.0
  m = 2.0
  q = 3
  write(*, nml=NML)
end

It is properly rejected by NAG, and leads to fun with ifort, depending on
the -stand setting.