Re: [AD] Error compiling MinGW Allegro with Cygwin with w32api-3.8-1

[Peter Wang <tjaden@xxxxxxxxxx>]

On 2006-12-19, Andrei Ellman <ae-a-alleg@xxxxxxxxxx> wrote:
> Hi,
> 
> I've discovered an issue when compiling MinGW Allegro 4.2.1 with Cygwin 
> with w32api-3.8-1 . If I downgrade to the w32api-3.7-1 package, the 
> error goes away. Note that in both cases, I installed dx80_mgw.zip after 
> I had installed the Cygwin package.
> 
> Here's the output for the offending compilation (note: All files up 
> until that point compiled just fine):
> 
...
> 
> I get the impression that mmsystem.h is the culprit. I did a diff 
> between the one from the 3.7.1 and 3.8.1 files, and this is what it came 
> up with:
> 
> 194a194
>  > #define WAVE_FORMAT_EXTENSIBLE 0xFFFE
> 1012c1013,1014
> < #ifndef _WAVEFORMATEX_
> ---
>  > #ifndef _LPCWAVEFORMATEX_DEFINED
>  > #define _LPCWAVEFORMATEX_DEFINED
> 
> 
> The changelog is at 
> http://cygwin.com/ml/cygwin-announce/2006-11/msg00039.html
> I believe the relevant entry to be:
> 
> * include/mmsystem.h (_LPCWAVEFORMATEX_DEFINED): Define.
>     Use as guard for the WAVEFORMATEX structure instead of
>     _WAVEFORMATEX_ to avoid clashes with DirectSound. Keep
>     _WAVEFORMATEX_ for compatibility.
> 
> 
> I'm not sure if this is a Cygwin or an Allegro related problem.

Thanks for the report.  In include/allegro/platform/almngw32.h we find
the offending lines:

    /* windows specific defines */

    #if (defined ALLEGRO_SRC)
    /* pathches to handle DX7 headers on a win9x system */

    /* should WINNT be defined on win9x systems? */
    #ifdef WINNT
       #undef WINNT
    #endif

    /* defined in windef.h */
    #ifndef HMONITOR_DECLARED
       #define HMONITOR_DECLARED 1
    #endif

    /* already defined... */
    #ifndef _LPCWAVEFORMATEX_DEFINED
       #define _LPCWAVEFORMATEX_DEFINED
    #endif

    #endif /* ALLEGRO_SRC */

_LPCWAVEFORMATEX_DEFINED is unconditionally defined, and if that happens
before mmsystem.h is included then LPCWAVEFORMATEX is not typedef'd,
causing later errors in mmsystem.h.

I don't know what the reason for that define is.  It seems to have been
added when the Mingw32 port was first added (r63 in SVN, path
allegro/trunk/include/allegro/almngw32.h).  It might be possible just to
remove the offending lines now.

Peter