[Bug fortran/100954] writing to a character opens unit -10

[tacodog311 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100954

--- Comment #2 from Taco Jerkface <tacodog311 at gmail dot com> ---
Agreed.  A typical user will use unit=42, when manually picking unit numbers. 
However the bug remains for automatic, newunit unit numbers.

To reproduce:
1) Open a "newunit" file.
2) close file
3) write to character string
4) "newunit" file appears open, even though it has been closed.


A more concise version of the code would be:

program inquire
      implicit none
      logical opened
      character(len=256) filename
      character(len=4) charstring

      integer iounit, itmp, ierr

      filename='testfile'

      ! new unit grabs -10
      open(newunit=iounit,file=trim(filename) )
      write(*,*) 'Opened unit',iounit

      ! now -10 is open
      inquire(iounit, opened=opened,iostat=ierr)
      write(*,*) 'Unit',iounit,'open?',opened,ierr

      ! close it
      close(iounit)
      write(*,*) 'Closed unit',iounit

      ! now -10 is closed
      inquire(iounit, opened=opened,iostat=ierr)
      write(*,*) 'Unit',iounit,'open?',opened,ierr

      itmp=0
      write(charstring, '(I4.4)') itmp
      write(*,*) 'wrote into charstring ', trim(charstring)

      ! now -10 is reported as open again, but it is not
      inquire(iounit, opened=opened,iostat=ierr)
      write(*,*) 'Unit',iounit,'open?',opened,ierr

endprogram inquire