[Bug fortran/64138] gfortran interface issue

["wong.david-c at epa dot gov" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64138

--- Comment #3 from david <wong.david-c at epa dot gov> ---
(In reply to david from comment #0)
> Hi,
> 
>    I have created a complex number module:
> 
>        module complex_number_module
>         implicit none
> 
>         integer, parameter :: loc_real_precision = 8
> 
>         type complex_number
>           real(kind=loc_real_precision) :: real_part, imag_part
>         end type complex_number
> 
>         interface c_sub
>           module procedure c_sub_cc,    &      ! z1 - z2
>                            c_sub_cr,    &      ! z1 - num, where num is a
> real number
>                            c_sub_rc            ! num - z1, where num is a
> real number
>         end interface
> 
> ! --------------------------------------------------------------------------
>         type (complex_number) function c_sub_cc (z1, z2)
> 
>         type (complex_number), intent(in) :: z1, z2
> 
>         c_sub_cc%real_part = z1%real_part - z2%real_part
>         c_sub_cc%imag_part = z1%imag_part - z2%imag_part
> 
>         end function c_sub_ccj
> 
> ! --------------------------------------------------------------------------
>         type (complex_number) function c_sub_cr (z1, num)
> 
>         type (complex_number),     intent(in) :: z1
>         real(kind=loc_real_precision), intent(in) :: num
> 
>         c_sub_cr%real_part = z1%real_part - num
>         c_sub_cr%imag_part = z1%imag_part
> 
>         end function c_sub_cr
> 
> ! --------------------------------------------------------------------------
>         type (complex_number) function c_sub_rc (num, z1)
> 
>         type (complex_number),     intent(in) :: z1
>         real(kind=loc_real_precision), intent(in) :: num
> 
>         c_sub_rc%real_part = num - z1%real_part
>         c_sub_rc%imag_part = - z1%imag_part
> 
>         end function c_sub_rc
> 
>       end module complex_number_module
> 
> When I compile with gfortran (version 4.6.4), I got the following error:
> 
> module_twoway_rrtmg_aero_optical_util.F:14.85:
> 
>                  c_sub_rc            ! num - z1, where num is a real number
>                                                                            1
> 
> Error: Ambiguous interfaces 'c_sub_rc' and 'c_sub_cr' in generic interface
> 'c_sub' at (1)
> 
> I don't see any ambiguity and I don't encounter any problem with other
> compilers such pgi and ifort. Please advise.
> 
> Cheers,
> David

Hi,

   I have attached a smaller version of the code and the way I compiled the
code is:

   gfortran -c -ffree-form d.F

Thanks,
David