Simplify C error handling (#9021)

Author: hugovk

src/_imaging.c

@@ -338,12 +338,6 @@ static const char *no_palette = "image has no palette";
 static const char *readonly = "image is readonly";
 /* static const char* no_content = "image has no content"; */
 
-void *
-ImagingError_OSError(void) {
-    PyErr_SetString(PyExc_OSError, "error when accessing file");
-    return NULL;
-}
-
 void *
 ImagingError_MemoryError(void) {
     return PyErr_NoMemory();
@@ -369,11 +363,6 @@ ImagingError_ValueError(const char *message) {
     return NULL;
 }
 
-void
-ImagingError_Clear(void) {
-    PyErr_Clear();
-}
-
 /* -------------------------------------------------------------------- */
 /* HELPERS                                */
 /* -------------------------------------------------------------------- */

src/libImaging/File.c

@@ -54,7 +54,7 @@ ImagingSavePPM(Imaging im, const char *outfile) {
 
     fp = fopen(outfile, "wb");
     if (!fp) {
-        (void)ImagingError_OSError();
+        PyErr_SetString(PyExc_OSError, "error when accessing file");
         return 0;
     }
 

src/libImaging/Imaging.h

@@ -270,8 +270,6 @@ ImagingSectionLeave(ImagingSectionCookie *cookie);
 /* Exceptions */
 /* ---------- */
 
-extern void *
-ImagingError_OSError(void);
 extern void *
 ImagingError_MemoryError(void);
 extern void *
@@ -280,8 +278,6 @@ extern void *
 ImagingError_Mismatch(void); /* maps to ValueError by default */
 extern void *
 ImagingError_ValueError(const char *message);
-extern void
-ImagingError_Clear(void);
 
 /* Transform callbacks */
 /* ------------------- */

src/libImaging/Storage.c

@@ -645,7 +645,7 @@ ImagingNewInternal(const char *mode, int xsize, int ysize, int dirty) {
         return im;
     }
 
-    ImagingError_Clear();
+    PyErr_Clear();
 
     // Try to allocate the image once more with smallest possible block size
     MUTEX_LOCK(&ImagingDefaultArena.mutex);