generic operator inheritance compile time error

[may_ka]

The code below implements an class hierachy with an abstract parent and two progeny and a generic assignment operator defined at the parent level. The operator points to a deferred routine which is subsequently defined for the two progeny classes.

Module Mod_AA
  Type, abstract :: ta
  contains
    Generic, Public :: Assignment(=) => CP
    Procedure(SubCP), Deferred, PAss :: CP
  End type ta
  Abstract Interface
    Subroutine SubCP(this,other)
      Import ta
      Class(ta), Intent(InOUt) :: this
      Class(ta), Intent(In) :: other
    end Subroutine SubCP
  End Interface
  Type, extends(ta) :: tb
    integer :: ib
  contains
    Procedure, Pass :: CP => SubCPB
  End type tb
  Type, extends(ta) :: tc
    integer :: ic
  contains
    Procedure, Pass :: CP => SubCPC
  End type tc
contains
  Subroutine SubCpB(this,other)
    class(tb), Intent(inout) :: this
    Class(ta), intent(in) :: other
    Select Type(x=>other)
    Class Is(tb)
      this%ib=x%ib
    Class Is(tc)
      this%ib=x%ic
    End Select
  End Subroutine SubCpB
  Subroutine SubCpC(this,other)
    class(tC), Intent(inout) :: this
    Class(ta), intent(in) :: other
    Select Type(x=>other)
    Class Is(tc)
      this%ic=x%ic
    Class Is(tb)
      this%ic=x%ib
    End Select
  End Subroutine SubCpC
End Module Mod_AA
Program Test
  use Mod_AA
  Type(tb) :: b
  type(tc) :: c
  c%ic=1
  b=c
  write(*,*) b%ib
End Program Test

From my understanding the code is correct and should work, and when using gfortran, it compiles and runs. However, using ifort 17.07 and 18.02 yields a compile time error:

user@linux:~$ ifort tmp.f90 
tmp.f90(51): error #6197: An assignment of different structure types is invalid.   
  b=c
----^
compilation aborted for tmp.f90 (code 1)

Is this a compiler bug or does gfortran allow for code which does not comply with the standard???

Any comments appreciated.

Chees

[IanH]

That would have been a compiler bug.  It compiles ok with current beta.