Make Cairo safer for --enable-gcc-warnings

* src/image.c (xcolor_to_argb32, pbm_load, jpeg_load_body, gif_load):
Avoid overflow warnings about ‘0xff << 24’.
(xpm_load, gif_load): Avoid unnecessary casts.
(gif_load): Fewer ifdefs.

src/image.c

@@ -1096,8 +1096,8 @@ image_ascent (struct image *img, struct face *face, struct glyph_slice *slice)
 static uint32_t
 xcolor_to_argb32 (XColor xc)
 {
-  return (0xff << 24) | ((xc.red / 256) << 16)
-      | ((xc.green / 256) << 8) | (xc.blue / 256);
+  return ((0xffu << 24) | ((xc.red / 256) << 16)
+	  | ((xc.green / 256) << 8) | (xc.blue / 256));
 }
 
 static uint32_t
@@ -3726,10 +3726,10 @@ xpm_load (struct frame *f, struct image *img)
     {
       int width = img->ximg->width;
       int height = img->ximg->height;
-      unsigned char *data = (unsigned char *) xmalloc (width*height*4);
+      void *data = xmalloc (width * height * 4);
       int i;
-      uint32_t *od = (uint32_t *)data;
-      uint32_t *id = (uint32_t *)img->ximg->data;
+      uint32_t *od = data;
+      uint32_t *id = (uint32_t *) img->ximg->data;
       char *mid = img->mask_img ? img->mask_img->data : 0;
       uint32_t bgcolor = get_spec_bg_or_alpha_as_argb (img, f);
 
@@ -5364,7 +5364,7 @@ pbm_load (struct frame *f, struct image *img)
   height = pbm_scan_number (&p, end);
 
 #ifdef USE_CAIRO
-  uint32_t *data = xmalloc (width * height * 4);
+  void *data = xmalloc (width * height * 4);
   uint32_t *dataptr = data;
 #endif
 
@@ -5540,7 +5540,7 @@ pbm_load (struct frame *f, struct image *img)
 	    r = (double) r * 255 / max_color_idx;
 	    g = (double) g * 255 / max_color_idx;
 	    b = (double) b * 255 / max_color_idx;
-            *dataptr++ = (0xff << 24) | (r << 16) | (g << 8) | b;
+            *dataptr++ = (0xffu << 24) | (r << 16) | (g << 8) | b;
 #else
 	    /* RGB values are now in the range 0..max_color_idx.
 	       Scale this to the range 0..0xffff supported by X.  */
@@ -6835,7 +6835,7 @@ jpeg_load_body (struct frame *f, struct image *img,
             r = mgr->cinfo.colormap[ir][i];
             g = mgr->cinfo.colormap[ig][i];
             b = mgr->cinfo.colormap[ib][i];
-            *dataptr++ = (0xff << 24) | (r << 16) | (g << 8) | b;
+            *dataptr++ = (0xffu << 24) | (r << 16) | (g << 8) | b;
           }
       }
 
@@ -7628,14 +7628,6 @@ gif_load (struct frame *f, struct image *img)
   EMACS_INT idx;
   int gif_err;
 
-#ifdef USE_CAIRO
-  unsigned char *data = 0;
-#else
-  unsigned long pixel_colors[256];
-  unsigned long bgcolor = 0;
-  XImagePtr ximg;
-#endif
-
   if (NILP (specified_data))
     {
       Lisp_Object file = x_find_image_file (specified_file);
@@ -7766,24 +7758,26 @@ gif_load (struct frame *f, struct image *img)
 
 #ifdef USE_CAIRO
   /* xzalloc so data is zero => transparent */
-  data = (unsigned char *) xzalloc (width * height * 4);
+  void *data = xzalloc (width * height * 4);
+  uint32_t *data32 = data;
   if (STRINGP (specified_bg))
     {
       XColor color;
       if (x_defined_color (f, SSDATA (specified_bg), &color, 0))
         {
-          uint32_t *dataptr = (uint32_t *)data;
+          uint32_t *dataptr = data32;
           int r = color.red/256;
           int g = color.green/256;
           int b = color.blue/256;
 
           for (y = 0; y < height; ++y)
             for (x = 0; x < width; ++x)
-              *dataptr++ = (0xff << 24) | (r << 16) | (g << 8) | b;
+              *dataptr++ = (0xffu << 24) | (r << 16) | (g << 8) | b;
         }
     }
 #else
   /* Create the X image and pixmap.  */
+  XImagePtr ximg;
   if (!image_create_x_image_and_pixmap (f, img, width, height, 0, &ximg, 0))
     {
       gif_close (gif, NULL);
@@ -7821,6 +7815,7 @@ gif_load (struct frame *f, struct image *img)
   init_color_table ();
 
 #ifndef USE_CAIRO
+  unsigned long bgcolor;
   if (STRINGP (specified_bg))
     bgcolor = x_alloc_image_color (f, img, specified_bg,
 				   FRAME_BACKGROUND_PIXEL (f));
@@ -7874,7 +7869,7 @@ gif_load (struct frame *f, struct image *img)
 
 #ifndef USE_CAIRO
       /* Allocate subimage colors.  */
-      memset (pixel_colors, 0, sizeof pixel_colors);
+      unsigned long pixel_colors[256] = { 0, };
 
       if (gif_color_map)
 	for (i = 0; i < gif_color_map->ColorCount; ++i)
@@ -7911,14 +7906,14 @@ gif_load (struct frame *f, struct image *img)
                     {
 #ifdef USE_CAIRO
                       uint32_t *dataptr =
-                        ((uint32_t*)data + ((row + subimg_top) * subimg_width
-                                            + x + subimg_left));
+                        (data32 + ((row + subimg_top) * subimg_width
+				   + x + subimg_left));
                       int r = gif_color_map->Colors[c].Red;
                       int g = gif_color_map->Colors[c].Green;
                       int b = gif_color_map->Colors[c].Blue;
 
                       if (transparency_color_index != c)
-                        *dataptr = (0xff << 24) | (r << 16) | (g << 8) | b;
+                        *dataptr = (0xffu << 24) | (r << 16) | (g << 8) | b;
 #else
                       XPutPixel (ximg, x + subimg_left, row + subimg_top,
                                  pixel_colors[c]);
@@ -7937,13 +7932,13 @@ gif_load (struct frame *f, struct image *img)
                   {
 #ifdef USE_CAIRO
                     uint32_t *dataptr =
-                      ((uint32_t*)data + ((y + subimg_top) * subimg_width
-                                          + x + subimg_left));
+                      (data32 + ((y + subimg_top) * subimg_width
+				 + x + subimg_left));
                     int r = gif_color_map->Colors[c].Red;
                     int g = gif_color_map->Colors[c].Green;
                     int b = gif_color_map->Colors[c].Blue;
                     if (transparency_color_index != c)
-                      *dataptr = (0xff << 24) | (r << 16) | (g << 8) | b;
+                      *dataptr = (0xffu << 24) | (r << 16) | (g << 8) | b;
 #else
                     XPutPixel (ximg, x + subimg_left, y + subimg_top,
                                pixel_colors[c]);