When I compile the following code:

module greet_m

  implicit none

  interface
     module subroutine hello (name)
       character (len=*), intent (in), optional :: name
     end subroutine hello
  end interface

end module greet_m

submodule (greet_m) greet_implementation_sm

contains

  module subroutine hello (name)
    character (len=*), intent (in), optional :: name

    if (present (name)) then
       print '("Hello ", a, "!")', name
    else
       print '("Hello World!")'
    end if
  end subroutine hello

end submodule greet_implementation_sm

program greeting

  use greet_m, only: hello

  implicit none

  call hello
  call hello ('John')

end program greeting

with:

gfortran -Wuse-without-only greeting.f90

gfortran warns me with:

greeting.f90:13:19:

   13 | submodule (greet_m) greet_implementation_sm
      |                   1
Warning: USE statement at (1) has no ONLY qualifier [-Wuse-without-only]

So it seems in submodule (greet_m) greet_implementation_sm, gfortran behaves like use greet_m and imports all symbols from greet_m module. This is normal behavior for submodule witch can access all symbols from parent module.

Did I missed something, or this is false positive warning from gfortran and I must fill a bug to them?