From 96305832bc0e1cecd35c193a0934046830ea8a02 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Fri, 11 Aug 2017 10:21:19 -0700
Subject: [PATCH] Fixed bug 3702 - Clear error messages of SDL_LoadObject for
 optional libraries

Simon Hug

Some code in SDL loads libraries with SDL_LoadObject to get more information or use newer APIs. SDL_LoadObject may fail, set an error message and SDL will continue with some fallback code. Since SDL will overwrite the error or exit the function with a return value that indicates success, the error form SDL_LoadObject for the optional stuff might as well be cleared right away.
---
 src/audio/SDL_audio.c                   | 1 +
 src/video/SDL_egl.c                     | 4 +++-
 src/video/windows/SDL_windowskeyboard.c | 1 +
 src/video/windows/SDL_windowsvideo.c    | 4 ++++
 4 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/audio/SDL_audio.c b/src/audio/SDL_audio.c
index 1243721a8f8a3..120555f9c222c 100644
--- a/src/audio/SDL_audio.c
+++ b/src/audio/SDL_audio.c
@@ -150,6 +150,7 @@ LoadLibSampleRate(void)
     SDL_assert(SRC_lib == NULL);
     SRC_lib = SDL_LoadObject(SDL_LIBSAMPLERATE_DYNAMIC);
     if (!SRC_lib) {
+        SDL_ClearError();
         return SDL_FALSE;
     }
 
diff --git a/src/video/SDL_egl.c b/src/video/SDL_egl.c
index ed0feb4c3c160..20884afc4167d 100644
--- a/src/video/SDL_egl.c
+++ b/src/video/SDL_egl.c
@@ -269,7 +269,9 @@ SDL_EGL_LoadLibrary(_THIS, const char *egl_path, NativeDisplayType native_displa
         }
     }
     if (SDL_strcasecmp(d3dcompiler, "none") != 0) {
-        SDL_LoadObject(d3dcompiler);
+        if (SDL_LoadObject(d3dcompiler) == NULL) {
+            SDL_ClearError();
+        }
     }
 #endif
 
diff --git a/src/video/windows/SDL_windowskeyboard.c b/src/video/windows/SDL_windowskeyboard.c
index 2018a30657224..7e79c6fa493ea 100644
--- a/src/video/windows/SDL_windowskeyboard.c
+++ b/src/video/windows/SDL_windowskeyboard.c
@@ -351,6 +351,7 @@ IME_Init(SDL_VideoData *videodata, HWND hwnd)
     videodata->ime_himm32 = SDL_LoadObject("imm32.dll");
     if (!videodata->ime_himm32) {
         videodata->ime_available = SDL_FALSE;
+        SDL_ClearError();
         return;
     }
     videodata->ImmLockIMC = (LPINPUTCONTEXT2 (WINAPI *)(HIMC))SDL_LoadFunction(videodata->ime_himm32, "ImmLockIMC");
diff --git a/src/video/windows/SDL_windowsvideo.c b/src/video/windows/SDL_windowsvideo.c
index 4b180c3af8d74..f6fc6f4e4199d 100644
--- a/src/video/windows/SDL_windowsvideo.c
+++ b/src/video/windows/SDL_windowsvideo.c
@@ -113,11 +113,15 @@ WIN_CreateDevice(int devindex)
         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");
+    } 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");
+    } else {
+        SDL_ClearError();
     }
 
     /* Set the function pointers */