与递归调用子程序有关的编译错误

Question

使用gfortran编译程序时，会出现以下错误：

quicksort.f95:73:25:
                 quicksort(ARR(1:J))
                         1
Error: Symbol ‘quicksort’ at (1) has already been host associated
quicksort.f95:77:25:
                 quicksort(ARR(I:N2))
                         1
Error: Symbol ‘quicksort’ at (1) has already been host associated

我创建的子程序具有以下代码

    recursive subroutine quicksort(ARR)
    implicit none
        integer, dimension(:), intent(inout) :: ARR
        integer I, J, X, AUX, N2
        logical :: CONTINUA

        N2 = SIZE(ARR)

        if (N2 <= 2) then
            if (N2 == 2) then
                AUX = ARR(1)
                if (ARR(1) > ARR(2)) then
                    ARR(1) = ARR(2)
                    ARR(2) = AUX
                end if
            end if
        else

            I=1; J=N2; X=ARR(N2/2)
            CONTINUA = .TRUE.

            do while (CONTINUA)
                do while (ARR(I) < X)
                    I = I + 1
                end do

                do while (ARR(J) > X)
                    J = J-1
                end do

                if (I <= J) then
                    AUX = ARR(I)
                    ARR(I) = ARR(J)
                    ARR(J) = AUX
                    I=I+1; J=J-1
                end if

                CONTINUA = (I <= J)
            end do

!BELOW ARE THE PROBLEM LINES

            if (J > 0) then
                quicksort(ARR(1:J))
            end if

            if (I < N2) then
                quicksort(ARR(I:N2))
            end if

        end if
    end subroutine quicksort

我甚至尝试重命名子例程，但错误仍然存​​在。我实际上不明白Symbol ‘quicksort’ at (1) has already been host associated错误的真正含义。我在互联网上搜索但没有得到这个错误的含义。

有人能告诉我错误在哪里吗？