The following source is compiled into wrong code:

interface
  elemental integer function foo(x)
    integer, intent(in), value :: x
  end function
end interface

  print *, foo(42)
  print *, foo([0,1])
end

For all versions of gfortran starting from 4.3 (and up to current trunk), the second call to FOO is miscompiled. Looking at the generated code (-fdump-tree-original), the first call is, as expected, by value:

      D.1882 = foo (42);
      _gfortran_transfer_integer_write (&dt_parm.0, &D.1882, 4);

while the second call is by-reference:

              D.1887 = A.2[S.3];
              D.1888 = foo (&D.1887);
              _gfortran_transfer_integer_write (&dt_parm.1, &D.1888, 4);

This can be confirmed by adding an actual FOO function such as:

elemental integer function foo(x)
  integer, intent(in), value :: x
  foo = x - 1
end function

Running the complete program then yields:

          41
  1370438451  1370438451