main: Indented SDL_main headers for readability, removed SDL2 compat macros.

Specifically, SDL_WinRTRunApp, SDL_UIKitRunApp, and SDL_GDKRunApp macros were
removed, as likely unnecessary to SDL3 users. A note was added to the
migration doc about how to roll replacements. These are not going into
SDL_oldnames.h.

Fixes #8245.

docs/README-migration.md

@@ -861,7 +861,15 @@ SDL3 doesn't have a static libSDLmain to link against anymore.
 Instead SDL_main.h is now a header-only library **and not included by SDL.h anymore**.
 
 Using it is really simple: Just `#include <SDL3/SDL_main.h>` in the source file with your standard
-`int main(int argc, char* argv[])` function.
+`int main(int argc, char* argv[])` function. See docs/README-main-functions.md for details.
+
+Several platform-specific entry point functions have been removed as unnecessary. If for some reason you explicitly need them, here are easy replacements:
+
+```c
+#define SDL_WinRTRunApp(MAIN_FUNC, RESERVED)  SDL_RunApp(0, NULL, MAIN_FUNC, RESERVED)
+#define SDL_UIKitRunApp(ARGC, ARGV, MAIN_FUNC)  SDL_RunApp(ARGC, ARGV, MAIN_FUNC, NULL)
+#define SDL_GDKRunApp(MAIN_FUNC, RESERVED)  SDL_RunApp(0, NULL, MAIN_FUNC, RESERVED)
+```
 
 ## SDL_metal.h
 

include/SDL3/SDL_main.h

@@ -121,7 +121,6 @@
         #define SDL_MAIN_AVAILABLE
 
     #elif defined(SDL_PLATFORM_NGAGE)
-
         /*
         TODO: not sure if it should be SDL_MAIN_NEEDED, in SDL2 ngage had a
                 main implementation, but wasn't mentioned in SDL_main.h
@@ -470,26 +469,8 @@ extern DECLSPEC void SDLCALL SDL_UnregisterApp(void);
 
 #endif /* defined(SDL_PLATFORM_WIN32) || defined(SDL_PLATFORM_GDK) */
 
-
-#ifdef SDL_PLATFORM_WINRT
-
-/* for compatibility with SDL2's function of this name */
-#define SDL_WinRTRunApp(MAIN_FUNC, RESERVED)  SDL_RunApp(0, NULL, MAIN_FUNC, RESERVED)
-
-#endif /* SDL_PLATFORM_WINRT */
-
-#ifdef SDL_PLATFORM_IOS
-
-/* for compatibility with SDL2's function of this name */
-#define SDL_UIKitRunApp(ARGC, ARGV, MAIN_FUNC)  SDL_RunApp(ARGC, ARGV, MAIN_FUNC, NULL)
-
-#endif /* SDL_PLATFORM_IOS */
-
 #ifdef SDL_PLATFORM_GDK
 
-/* for compatibility with SDL2's function of this name */
-#define SDL_GDKRunApp(MAIN_FUNC, RESERVED)  SDL_RunApp(0, NULL, MAIN_FUNC, RESERVED)
-
 /**
  * Callback from the application to let the suspend continue.
  *
@@ -515,7 +496,6 @@ extern DECLSPEC void SDLCALL SDL_GDKSuspendComplete(void);
         #include <SDL3/SDL_main_impl.h>
 
     #elif defined(SDL_PLATFORM_WINRT) /* C++ platforms */
-
         #ifdef __cplusplus
         #include <SDL3/SDL_main_impl.h>
         #else
@@ -530,7 +510,6 @@ extern DECLSPEC void SDLCALL SDL_GDKSuspendComplete(void);
         #endif /* __cplusplus */
 
     #endif /* C++ platforms like SDL_PLATFORM_WINRT etc */
-
+#endif
-#endif /* SDL_MAIN_HANDLED */
 
 #endif /* SDL_main_h_ */

include/SDL3/SDL_main_impl.h

@@ -39,7 +39,7 @@
        (the user's main() will be renamed to SDL_main so it can be called from here) */
     #ifdef main
         #undef main
-#endif /* main */
+    #endif
 
     #ifdef SDL_MAIN_USE_CALLBACKS
 
@@ -104,6 +104,7 @@ int main(int argc, char *argv[])
             #ifdef __cplusplus
             extern "C" {
             #endif
+
             #if defined( UNICODE ) && UNICODE
             int WINAPI wWinMain(HINSTANCE hInst, HINSTANCE hPrev, PWSTR szCmdLine, int sw)
             #else /* ANSI */
@@ -116,11 +117,13 @@ int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrev, LPSTR szCmdLine, int sw)
                 (void)sw;
                 return SDL_RunApp(0, NULL, SDL_main, NULL);
             }
+
             #ifdef __cplusplus
             } /* extern "C" */
             #endif
 
             /* end of SDL_PLATFORM_WIN32 and SDL_PLATFORM_GDK impls */
+
         #elif defined(SDL_PLATFORM_WINRT)
 
             /* WinRT main based on SDL_winrt_main_NonXAML.cpp, placed in the public domain by David Ludwig  3/13/14 */
@@ -163,10 +166,7 @@ int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrev, LPSTR szCmdLine, int sw)
             */
             #ifdef _MSC_VER
             #pragma warning(disable : 4447)
-#endif
-
             /* Make sure the function to initialize the Windows Runtime gets linked in. */
-#ifdef _MSC_VER
             #pragma comment(lib, "runtimeobject.lib")
             #endif
 
@@ -182,8 +182,8 @@ int CALLBACK WinMain(HINSTANCE, HINSTANCE, LPSTR, int)
             #endif
 
             /* end of WinRT impl */
-#elif defined(SDL_PLATFORM_NGAGE)
 
+        #elif defined(SDL_PLATFORM_NGAGE)
             /* same typedef as in ngage SDKs e32def.h */
             typedef signed int TInt;
             /* TODO: if it turns out that this only works when built as C++,
@@ -196,7 +196,6 @@ TInt E32Main()
             /* end of SDL_PLATFORM_NGAGE impl */
 
         #else /* platforms that use a standard main() and just call SDL_RunApp(), like iOS and 3DS */
-
             int main(int argc, char *argv[])
             {
                 return SDL_RunApp(argc, argv, SDL_main, NULL);