Error for binary operation

[Blane_J_]

Hi, the following code produces an error with ifort 2018u2 on x64 platform:

module test1
    implicit none
    
    type, abstract :: tp1
        private
    contains
        private
        procedure(iequals), public, pass, deferred :: equals
    end type tp1
    
    abstract interface
        function iequals(this, obj)
            import tp1
            logical                :: iequals
            class(tp1), intent(in) :: this
            class(tp1), intent(in) :: obj
        end function iequals
    end interface
    
end module test1

module test2
    use test1, only: tp1
    implicit none
    
    type, extends(tp1) :: tp2
        private
        integer :: var2
    contains
        private
        procedure, public, pass :: equals => equalsfunc
    end type tp2

    contains
    
    function equalsfunc(this, obj)
        implicit none

        logical                :: equalsfunc
        class(tp2), intent(in) :: this
        class(tp1), intent(in) :: obj

        select type(obj)
        type is(tp2)
            equalsfunc = (this % var2 == obj % var2)
        class default
            equalsfunc = .false.
        end select

    end function equalsfunc

end module test2

module test3
    use test1, only: tp1
    use test2, only: tp2
    implicit none
    
    type, extends(tp1) :: tp3
        private
        type(tp2) :: var3
    contains
        private
        procedure, public, pass :: equals => equalsfunc
    end type tp3

    contains
    
    function equalsfunc(this, obj)
        implicit none

        logical                :: equalsfunc
        class(tp3), intent(in) :: this
        class(tp1), intent(in) :: obj

        select type(obj)
        type is(tp3)
            equalsfunc = (this % var3 == obj % var3)
        class default
            equalsfunc = .false.
        end select

    end function equalsfunc

end module test3

Error message is:

error #6355: This binary operation is invalid for this data type.    [VAR3]

on line 78. Is this a bug and is there any workaround that I can temporarily make it through ? Thanks for any help.

[IanH]

There is no generic binding specification for ASSIGNMENT(=) in the code as shown. The error message makes sense if this is really the case.
 

[Lorri_M_Intel]

I hate disagreeing with Ian (it's almost as bad as disagreeing with Steve) but I think the problem is that there is no defined operator "==" specified for something of type TP2.

the line in question is asking "is this%var3 the same as obj%var3" but there is nothing to define what "the same" means between two objects of type TP2.

If what you care about is the integer field in TP2, then the quickest solution is to change line 78 to:

equalsfunc = (this % var3 % var2 == obj % var3 %var2 )

Or, you can create a defined operator for the "==" operator.

             --Lorri

[Blane_J_]

Lorri Menard (Intel) wrote:

If what you care about is the integer field in TP2, then the quickest solution is to change line 78 to:

equalsfunc = (this % var3 % var2 == obj % var3 %var2 )

@lanH, @Lorri,

Thanks for your help. BTW, as var2 is private, the quickest solution may not work properly for the example.

[IanH]

Oops - I muddled OPERATOR(==) and ASSIGNMENT(=).  There's no generic binding specification for OPERATOR(==) in the code as shown, etc, etc.