[Bug fortran/30381] New: ISHFTC() constant folding is broken.

["brooks at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

According to example in the F95 standard, this program should output 5, if
given inputs of 2 and 3.  It does indeed do this.

  program shiftcirc
    integer i, j
    read(*,*) i, j
    write(*,*) ishftc( 3, i, j )
  end program

However, if we replace i and j with constants, things start breaking.  First:

  program shiftcirc
    write(*,*) ishftc( 3, 2, 3 )
  end program

This outputs -3, which is incorrect.  Worse, if we do this:

  program shiftcirc
    integer i
    read(*,*) i
    write(*,*) ishftc( 3, 2, i )
  end program

This gives an error on compilation:

debian-gfortran:~/test> ../bin-trunk/bin/gfortran ishftc.f90 -o ishftc
ishftc.f90:4.26:

  write(*,*) ishftc( 3, 2, i )
                         1
Error: Invalid third argument of ISHFTC at (1)


-- 
           Summary: ISHFTC() constant folding is broken.
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: wrong-code, rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: brooks at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30381