[AD] END_OF_MAIN removal patch for msvc

[torhu <torhu.lists@xxxxxxxxxx>]

Hello, people.  There was a discussion about removing END_OF_MAIN this 
summer, see http://tinyurl.com/5jd23y (mailing list archive).  Here's a 
patch and some thoughts about this, please comment. :)

I've had some trouble building allegro 5 on msvc, but now I've got it 
working.  So I've attached a patch which makes END_OF_MAIN just an empty 
macro on msvc.

I've added ALLEGRO_ALLOW_WINMAIN as a way to let users use WinMain 
without having to override the /entry switch themselves.

Some questions remain:


1) This means that apps built with allegro 5 on msvc will by default 
have a console window.  But this is what happens on other Windows 
compilers already, at least mingw does this.  So how to disable the 
console will definitely become a FAQ for msvc users.  Adding the 
required linker option to allegro headers is an option.  See below.

#ifdef ALLEGRO_USE_CONSOLE
  #pragma comment(linker,"/SUBSYSTEM:windows").
#endif

Not sure I like this, though.  Seems a bit over the top, or what?


2) This opens up the possibility to remove ALLEGRO_USE_CONSOLE and 
ALLEGRO_CONSOLE_OK.  They're only useful on Windows.  Other platforms 
always define ALLEGRO_CONSOLE_OK, and ignore ALLEGRO_USE_CONSOLE.

ALLEGRO_CONSOLE_OK has dubious value, as the console can be disabled or 
enabled by flipping a switch in the exe header after the app is already 
built.  A runtime check could probably be added, if there's a real need 
for it.


3) OS X and QNX uses END_OF_MAIN to get hold of the address of 
_mangled_main.  A different solution needed?  And is 
ALLEGRO_WITH_MAGIC_MAIN needed?  It's off by default.


4) Most of the examples and tools that come with allegro need to be 
built without a console window by setting something in the build config, 
since END_OF_MAIN no longer takes care of this.  CMake's ADD_EXECUTABLE 
function has a WIN32 flag that seems to be the right way to do this. 
Maybe the 'example' macro in allegro's build system could get a similar 
flag? I'll leave that to someone who knows the build system.

Index: include/allegro5/platform/alwin.h
===================================================================
--- include/allegro5/platform/alwin.h	(revision 11221)
+++ include/allegro5/platform/alwin.h	(working copy)
@@ -24,44 +24,7 @@
    #include <windows.h>
 #endif
 
-/*******************************************/
-/********** magic main emulation ***********/
-/*******************************************/
-#ifdef __cplusplus
-extern "C" {
-#endif
 
-AL_FUNC(int, _WinMain, (void *_main, void *hInst, void *hPrev, char *Cmd, int nShow));
-
-#ifdef __cplusplus
-}
-#endif
-
-
-#if (!defined ALLEGRO_NO_MAGIC_MAIN) && (!defined ALLEGRO_SRC)
-
-   #define ALLEGRO_MAGIC_MAIN
-   #define main _mangled_main
-   #undef END_OF_MAIN
-
-   /* disable strict pointer typing because of the vague prototype below */
-   #define NO_STRICT
-
-   #ifdef __cplusplus
-      extern "C" int __stdcall WinMain(HINSTANCE hInst, HINSTANCE hPrev, char *Cmd, int nShow);
-   #endif
-
-   #define END_OF_MAIN()                                                     \
-                                                                             \
-      int __stdcall WinMain(HINSTANCE hInst, HINSTANCE hPrev, char *Cmd, int nShow)  \
-      {                                                                      \
-         return _WinMain((void *)_mangled_main, hInst, hPrev, Cmd, nShow);   \
-      }
-
-#endif
-
-
-
 /*******************************************/
 /************* system drivers **************/
 /*******************************************/
Index: include/allegro5/platform/almsvc.h
===================================================================
--- include/allegro5/platform/almsvc.h	(revision 11221)
+++ include/allegro5/platform/almsvc.h	(working copy)
@@ -46,8 +46,9 @@
    #define ALLEGRO_NO_MAGIC_MAIN
 #endif
 
-#ifdef ALLEGRO_AND_MFC
-   #define ALLEGRO_NO_MAGIC_MAIN
+/* stop msvc linker complaining about missing WinMain */
+#if (!defined ALLEGRO_ALLOW_WINMAIN) && (!defined ALLEGRO_LIB_BUILD)
+   #pragma comment(linker,"/ENTRY:mainCRTStartup")
 #endif