Fixed ISO C99 compatibility

SDL now builds with gcc 7.2 with the following command line options:
-Wall -pedantic-errors -Wno-deprecated-declarations -Wno-overlength-strings --std=c99

src/video/windows/SDL_windowsevents.c

@@ -1086,7 +1086,9 @@ IsWin10FCUorNewer(void)
     HMODULE handle = GetModuleHandleW(L"ntdll.dll");
     if (handle) {
         typedef LONG(WINAPI* RtlGetVersionPtr)(struct SDL_WIN_OSVERSIONINFOW*);
-        RtlGetVersionPtr getVersionPtr = (RtlGetVersionPtr)GetProcAddress(handle, "RtlGetVersion");
+        RtlGetVersionPtr getVersionPtr;
+       
+        *(void**)&getVersionPtr = GetProcAddress(handle, "RtlGetVersion");
         if (getVersionPtr != NULL) {
             struct SDL_WIN_OSVERSIONINFOW info;
             SDL_zero(info);

src/video/windows/SDL_windowskeyboard.c

@@ -354,10 +354,10 @@ IME_Init(SDL_VideoData *videodata, HWND hwnd)
         SDL_ClearError();
         return;
     }
-    videodata->ImmLockIMC = (LPINPUTCONTEXT2 (WINAPI *)(HIMC))SDL_LoadFunction(videodata->ime_himm32, "ImmLockIMC");
-    videodata->ImmUnlockIMC = (BOOL (WINAPI *)(HIMC))SDL_LoadFunction(videodata->ime_himm32, "ImmUnlockIMC");
-    videodata->ImmLockIMCC = (LPVOID (WINAPI *)(HIMCC))SDL_LoadFunction(videodata->ime_himm32, "ImmLockIMCC");
-    videodata->ImmUnlockIMCC = (BOOL (WINAPI *)(HIMCC))SDL_LoadFunction(videodata->ime_himm32, "ImmUnlockIMCC");
+    *(void**)&videodata->ImmLockIMC = SDL_LoadFunction(videodata->ime_himm32, "ImmLockIMC");
+    *(void**)&videodata->ImmUnlockIMC = SDL_LoadFunction(videodata->ime_himm32, "ImmUnlockIMC");
+    *(void**)&videodata->ImmLockIMCC = SDL_LoadFunction(videodata->ime_himm32, "ImmLockIMCC");
+    *(void**)&videodata->ImmUnlockIMCC = SDL_LoadFunction(videodata->ime_himm32, "ImmUnlockIMCC");
 
     IME_SetWindow(videodata, hwnd);
     videodata->ime_himc = ImmGetContext(hwnd);
@@ -654,9 +654,9 @@ IME_SetupAPI(SDL_VideoData *videodata)
     if (!hime)
         return;
 
-    videodata->GetReadingString = (UINT (WINAPI *)(HIMC, UINT, LPWSTR, PINT, BOOL*, PUINT))
+    *(void**)&videodata->GetReadingString =
         SDL_LoadFunction(hime, "GetReadingString");
-    videodata->ShowReadingWindow = (BOOL (WINAPI *)(HIMC, BOOL))
+    *(void**)&videodata->ShowReadingWindow =
         SDL_LoadFunction(hime, "ShowReadingWindow");
 
     if (videodata->ShowReadingWindow) {

src/video/windows/SDL_windowsopengl.c

@@ -119,15 +119,15 @@ WIN_GL_LoadLibrary(_THIS, const char *path)
 
     /* Load function pointers */
     handle = _this->gl_config.dll_handle;
-    _this->gl_data->wglGetProcAddress = (void *(WINAPI *) (const char *))
+    *(void**)&_this->gl_data->wglGetProcAddress =
         SDL_LoadFunction(handle, "wglGetProcAddress");
-    _this->gl_data->wglCreateContext = (HGLRC(WINAPI *) (HDC))
+    *(void**)&_this->gl_data->wglCreateContext =
         SDL_LoadFunction(handle, "wglCreateContext");
-    _this->gl_data->wglDeleteContext = (BOOL(WINAPI *) (HGLRC))
+    *(void**)&_this->gl_data->wglDeleteContext =
         SDL_LoadFunction(handle, "wglDeleteContext");
-    _this->gl_data->wglMakeCurrent = (BOOL(WINAPI *) (HDC, HGLRC))
+    *(void**)&_this->gl_data->wglMakeCurrent =
         SDL_LoadFunction(handle, "wglMakeCurrent");
-    _this->gl_data->wglShareLists = (BOOL(WINAPI *) (HGLRC, HGLRC))
+    *(void**)&_this->gl_data->wglShareLists =
         SDL_LoadFunction(handle, "wglShareLists");
 
     if (!_this->gl_data->wglGetProcAddress ||
@@ -409,7 +409,7 @@ WIN_GL_InitExtensions(_THIS)
     }
     _this->gl_data->wglMakeCurrent(hdc, hglrc);
 
-    wglGetExtensionsStringARB = (const char *(WINAPI *) (HDC))
+    *(void**)&wglGetExtensionsStringARB =
         _this->gl_data->wglGetProcAddress("wglGetExtensionsStringARB");
     if (wglGetExtensionsStringARB) {
         extensions = wglGetExtensionsStringARB(hdc);
@@ -420,13 +420,9 @@ WIN_GL_InitExtensions(_THIS)
     /* Check for WGL_ARB_pixel_format */
     _this->gl_data->HAS_WGL_ARB_pixel_format = SDL_FALSE;
     if (HasExtension("WGL_ARB_pixel_format", extensions)) {
-        _this->gl_data->wglChoosePixelFormatARB = (BOOL(WINAPI *)
-                                                   (HDC, const int *,
-                                                    const FLOAT *, UINT,
-                                                    int *, UINT *))
+        *(void**)&_this->gl_data->wglChoosePixelFormatARB =
             WIN_GL_GetProcAddress(_this, "wglChoosePixelFormatARB");
-        _this->gl_data->wglGetPixelFormatAttribivARB =
-            (BOOL(WINAPI *) (HDC, int, int, UINT, const int *, int *))
+        *(void**)&_this->gl_data->wglGetPixelFormatAttribivARB =
             WIN_GL_GetProcAddress(_this, "wglGetPixelFormatAttribivARB");
 
         if ((_this->gl_data->wglChoosePixelFormatARB != NULL) &&
@@ -438,9 +434,9 @@ WIN_GL_InitExtensions(_THIS)
     /* Check for WGL_EXT_swap_control */
     _this->gl_data->HAS_WGL_EXT_swap_control_tear = SDL_FALSE;
     if (HasExtension("WGL_EXT_swap_control", extensions)) {
-        _this->gl_data->wglSwapIntervalEXT =
+        *(void**)&_this->gl_data->wglSwapIntervalEXT =
             WIN_GL_GetProcAddress(_this, "wglSwapIntervalEXT");
-        _this->gl_data->wglGetSwapIntervalEXT =
+        *(void**)&_this->gl_data->wglGetSwapIntervalEXT =
             WIN_GL_GetProcAddress(_this, "wglGetSwapIntervalEXT");
         if (HasExtension("WGL_EXT_swap_control_tear", extensions)) {
             _this->gl_data->HAS_WGL_EXT_swap_control_tear = SDL_TRUE;
@@ -721,9 +717,8 @@ WIN_GL_CreateContext(_THIS, SDL_Window * window)
             return NULL;
         }
 
-        wglCreateContextAttribsARB =
-            (PFNWGLCREATECONTEXTATTRIBSARBPROC) _this->gl_data->
-            wglGetProcAddress("wglCreateContextAttribsARB");
+        *(void**)&wglCreateContextAttribsARB =
+            _this->gl_data->wglGetProcAddress("wglCreateContextAttribsARB");
         if (!wglCreateContextAttribsARB) {
             SDL_SetError("GL 3.x is not supported");
             context = temp_context;

src/video/windows/SDL_windowsvideo.c

@@ -113,16 +113,16 @@ WIN_CreateDevice(int devindex)
 
     data->userDLL = SDL_LoadObject("USER32.DLL");
     if (data->userDLL) {
-        data->CloseTouchInputHandle = (BOOL (WINAPI *)(HTOUCHINPUT)) SDL_LoadFunction(data->userDLL, "CloseTouchInputHandle");
-        data->GetTouchInputInfo = (BOOL (WINAPI *)(HTOUCHINPUT, UINT, PTOUCHINPUT, int)) SDL_LoadFunction(data->userDLL, "GetTouchInputInfo");
-        data->RegisterTouchWindow = (BOOL (WINAPI *)(HWND, ULONG)) SDL_LoadFunction(data->userDLL, "RegisterTouchWindow");
+        *(void**)&data->CloseTouchInputHandle = SDL_LoadFunction(data->userDLL, "CloseTouchInputHandle");
+        *(void**)&data->GetTouchInputInfo = SDL_LoadFunction(data->userDLL, "GetTouchInputInfo");
+        *(void**)&data->RegisterTouchWindow = SDL_LoadFunction(data->userDLL, "RegisterTouchWindow");
     } else {
         SDL_ClearError();
     }
 
     data->shcoreDLL = SDL_LoadObject("SHCORE.DLL");
     if (data->shcoreDLL) {
-        data->GetDpiForMonitor = (HRESULT (WINAPI *)(HMONITOR, MONITOR_DPI_TYPE, UINT *, UINT *)) SDL_LoadFunction(data->shcoreDLL, "GetDpiForMonitor");
+        *(void**)&data->GetDpiForMonitor = SDL_LoadFunction(data->shcoreDLL, "GetDpiForMonitor");
     } else {
         SDL_ClearError();
     }
@@ -256,7 +256,7 @@ D3D_LoadDLL(void **pD3DDLL, IDirect3D9 **pDirect3D9Interface)
         typedef HRESULT (WINAPI *Direct3DCreate9Ex_t)(UINT SDKVersion, IDirect3D9Ex **ppD3D);
         Direct3DCreate9Ex_t Direct3DCreate9ExFunc;
 
-        Direct3DCreate9ExFunc = (Direct3DCreate9Ex_t)SDL_LoadFunction(*pD3DDLL, "Direct3DCreate9Ex");
+        *(void**)&Direct3DCreate9ExFunc = SDL_LoadFunction(*pD3DDLL, "Direct3DCreate9Ex");
         if (Direct3DCreate9ExFunc) {
             IDirect3D9Ex *pDirect3D9ExInterface;
             HRESULT hr = Direct3DCreate9ExFunc(D3D_SDK_VERSION, &pDirect3D9ExInterface);
@@ -271,7 +271,7 @@ D3D_LoadDLL(void **pD3DDLL, IDirect3D9 **pDirect3D9Interface)
         }
 #endif /* USE_D3D9EX */
 
-        Direct3DCreate9Func = (Direct3DCreate9_t)SDL_LoadFunction(*pD3DDLL, "Direct3DCreate9");
+        *(void**)&Direct3DCreate9Func = SDL_LoadFunction(*pD3DDLL, "Direct3DCreate9");
         if (Direct3DCreate9Func) {
             *pDirect3D9Interface = Direct3DCreate9Func(D3D_SDK_VERSION);
             if (*pDirect3D9Interface) {
@@ -338,9 +338,7 @@ DXGI_LoadDLL(void **pDXGIDLL, IDXGIFactory **pDXGIFactory)
     if (*pDXGIDLL) {
         HRESULT (WINAPI *CreateDXGI)(REFIID riid, void **ppFactory);
 
-        CreateDXGI =
-            (HRESULT (WINAPI *) (REFIID, void**)) SDL_LoadFunction(*pDXGIDLL,
-            "CreateDXGIFactory");
+        *(void**)&CreateDXGI = SDL_LoadFunction(*pDXGIDLL, "CreateDXGIFactory");
         if (CreateDXGI) {
             GUID dxgiGUID = {0x7b7166ec,0x21c7,0x44ae,{0xb2,0x1a,0xc9,0xae,0x32,0x1a,0xe3,0x69}};
             if (!SUCCEEDED(CreateDXGI(&dxgiGUID, (void**)pDXGIFactory))) {

src/video/windows/SDL_windowsvulkan.c

@@ -57,13 +57,13 @@ int WIN_Vulkan_LoadLibrary(_THIS, const char *path)
         return -1;
     SDL_strlcpy(_this->vulkan_config.loader_path, path,
                 SDL_arraysize(_this->vulkan_config.loader_path));
-    vkGetInstanceProcAddr = (PFN_vkGetInstanceProcAddr)SDL_LoadFunction(
+    *(void**)vkGetInstanceProcAddr = SDL_LoadFunction(
         _this->vulkan_config.loader_handle, "vkGetInstanceProcAddr");
     if(!vkGetInstanceProcAddr)
         goto fail;
-    _this->vulkan_config.vkGetInstanceProcAddr = (void *)vkGetInstanceProcAddr;
+    _this->vulkan_config.vkGetInstanceProcAddr = vkGetInstanceProcAddr;
     _this->vulkan_config.vkEnumerateInstanceExtensionProperties =
-        (void *)((PFN_vkGetInstanceProcAddr)_this->vulkan_config.vkGetInstanceProcAddr)(
+        (PFN_vkEnumerateInstanceExtensionProperties)_this->vulkan_config.vkGetInstanceProcAddr(
             VK_NULL_HANDLE, "vkEnumerateInstanceExtensionProperties");
     if(!_this->vulkan_config.vkEnumerateInstanceExtensionProperties)
         goto fail;