Re: Dll entry point aliasing

[Janne Blomqvist <blomqvist dot janne at gmail dot com>]

On Sun, Jun 22, 2014 at 5:49 PM, John Barnes <johnbarnes2858@gmail.com> wrote:
> I have a FORTRAN dll that I have compiled and used in a couple of
> FORTRAN dialects. Seems that gFORTRAN (used in the MinGW32 environment
> on Windows 7) sees the entry points a little differently.
>
> This is how one of the entry points is defined in the FORTRAN code:
>
> subroutine XXXX_ENGINE_INITIALISE(args, success_code)
>     !DEC$ ATTRIBUTES DLLEXPORT :: XXXX_ENGINE_INITIALISE
>     !DEC$ ATTRIBUTES ALIAS:'_XXXX_ENGINE_INITIALISE' ::
> XXXX_ENGINE_INITIALISE
>     character(*), intent(in) :: args
>     integer, intent(out) :: success_code ! 0: ok, -ive fatal error, +ive warning
>
> The above is used with C# calling code like:
>
>         [DllImport(ExternalDll_C.Filename,
>             EntryPoint = "XXXX_ENGINE_INITIALISE",
>             ExactSpelling = false,
>             CallingConvention = CallingConvention.Cdecl)
>         ]
>         internal static extern void XXXX_ENGINE_INITIALISE(
>             [MarshalAs(UnmanagedType.LPStr)] StringBuilder inString,
>             ref int successCode, // 0: ok, -ive fatal error, +ive warning
>             int inStringLength);
>
> Compile the above with other dialects of FORTRAN I have available and
> Dependency Walker shows the dll has the expected entry point
> XXXX_ENGINE_INITIALISE.
>
> Compile using gFORTRAN and the entry point comes out as:
>
>         xxxx_engine_initialise_
>
> I suspect that gFORTRAN does not recognise the DEC$ comment directives
> and just applies its own name mangling. Is there a way I can change
> that? Ideally with some other comment directive?

Indeed, GFortran does not recognize DEC$ directives. GFortran has its
own (similar) attribute syntax, see Section 7.2 in the manual for more
info. However, GFortran does not support an equivalent to the DEC$
alias attribute, as by the time the GCC attribute syntax was
introduced, there was already a standardized way of doing the same,
namely the bind(C, name="XXX...") specifier. Please see Section 7.1.4
in the manual for more info.





-- 
Janne Blomqvist