[Bug fortran/52387] New: I/O wrong output with nonadvancing output

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52387

             Bug #: 52387
           Summary: I/O wrong output with nonadvancing output
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: bur...@gcc.gnu.org
                CC: jvdeli...@gcc.gnu.org


[Vaguely related: PR 52251]

Bob Corbett asked at c.l.f what the program below produces with the different
compilers. He thinks that the proper output should be:

ABCDMNOPIJKL

while gfortran produces

ABCDMNOP

(or actually, it [and NAG f95] produce [cf. modified program]:
>ABCDMNOP    <

with trailing spaces.)

Reasoning:

---------------- <cut> ---------------- 
According to interpretation 000024 of the Fortran 95 standard

Page 136. At the end of the last paragraph of subclause 9.2.1.3.1
[136:33] add
   If a nonadvancing output statement leaves a file positioned within
   the current record and no further output statement is executed
   for the file before it is closed or a BACKSPACE, ENDFILE, or REWIND
   statement is executed for it, the file is positioned after the
   current record before the specified action is performed.

The corresponding statement in the Fortran 2008 standard is
paragraph 2 of Clause 9.3.4.2.  Based on that statement and
on paragraph 4 of non-normative Clause C.6.2 of the
Fortran 2008 standard, my reading is that the output should
be

ABCDMNOPIJKL
---------------- </cut> ----------------

See complete thread at
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/694050b1806da367


Results of the various compilers:


Bob's expected result, Pathscale 4.0, Openf95 5.0, OpenUH/Open64
ABCDMNOPIJKL

gfortran (4.1 to 4.7), NAG 5.1, 
ABCDMNOP

g95, Silverfrost ftn95, ifort 11.1/12.1
ABCDEFGHIJKL 

sunf95 10/latest Oracle f95, IBM xlf, Microsoft V 3.31 (1985)
MNOP

Lahey:
ABCDMNOP


      PROGRAM MAIN
        CHARACTER*12 STR
        OPEN (10, FILE='XXX', POSITION='REWIND')
        WRITE (10, '(A)') 'ABCDEFGHIJKL'
        REWIND 10
        READ (10, '(TR4)', ADVANCE='NO')
        WRITE (10, '(TL2, A)', ADVANCE='NO') 'MNOP'
        REWIND 10
        READ (10, '(A)') STR
        PRINT '(3A)', STR
!        PRINT '(3A)', '>',STR,'<'
        CLOSE (10, STATUS='DELETE')
      END