Pacify --enable-gcc-warnings --with-cairo

Problem reported by Alexander Kuleshov in:
http://lists.gnu.org/archive/html/emacs-devel/2016-01/msg01289.html
* src/gtkutil.c (xg_get_page_setup):
Use switch rather than if-then-else.
* src/image.c (COLOR_TABLE_SUPPORT):
Define directly rather than via #define and optional later #undef.
(lookup_rgb_color) [USE_CAIRO && ENABLE_CHECKING]:
Crash when the pixel is undefined, as there is a genuine bug
here (Bug#22442).
* src/image.c (tiff_load, gif_load, svg_load_image)
(x_kill_gs_process) [USE_CAIRO]:
* src/xterm.c (x_draw_fringe_bitmap) [USE_CAIRO]:
Omit unused locals, or move them to where they’re needed.
(x_clear_area1): Now ATTRIBUTE_UNUSED.

1 files changed, 27 insertions, 39 deletions

diff --git a/src/image.c b/src/image.c
index 8bb5ff77b22..4681cba1f87 100644
--- a/src/image.c
+++ b/src/image.c
@@ -57,8 +57,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #endif /* HAVE_WINDOW_SYSTEM */
 
 #ifdef HAVE_X_WINDOWS
-#define COLOR_TABLE_SUPPORT 1
-
 typedef struct x_bitmap_record Bitmap_Record;
 #define GET_PIXEL(ximg, x, y) XGetPixel (ximg, x, y)
 #define NO_PIXMAP None
@@ -74,9 +72,6 @@ typedef struct x_bitmap_record Bitmap_Record;
 # include "w32.h"
 #endif
 
-/* W32_TODO : Color tables on W32.  */
-#undef COLOR_TABLE_SUPPORT
-
 typedef struct w32_bitmap_record Bitmap_Record;
 #define GET_PIXEL(ximg, x, y) GetPixel (ximg, x, y)
 #define NO_PIXMAP 0
@@ -89,13 +84,7 @@ typedef struct w32_bitmap_record Bitmap_Record;
 
 #endif /* HAVE_NTGUI */
 
-#ifdef USE_CAIRO
-#undef COLOR_TABLE_SUPPORT
-#endif
-
 #ifdef HAVE_NS
-#undef COLOR_TABLE_SUPPORT
-
 typedef struct ns_bitmap_record Bitmap_Record;
 
 #define GET_PIXEL(ximg, x, y) XGetPixel (ximg, x, y)
@@ -109,6 +98,12 @@ typedef struct ns_bitmap_record Bitmap_Record;
 #define DefaultDepthOfScreen(screen) x_display_list->n_planes
 #endif /* HAVE_NS */
 
+#if (defined HAVE_X_WINDOWS \
+     && ! (defined HAVE_NTGUI || defined USE_CAIRO || defined HAVE_NS))
+/* W32_TODO : Color tables on W32.  */
+# define COLOR_TABLE_SUPPORT 1
+#endif
+
 static void x_disable_image (struct frame *, struct image *);
 static void x_edge_detection (struct frame *, struct image *, Lisp_Object,
                               Lisp_Object);
@@ -4615,16 +4610,13 @@ colors_in_color_table (int *n)
 static unsigned long
 lookup_rgb_color (struct frame *f, int r, int g, int b)
 {
-  unsigned long pixel;
-
 #ifdef HAVE_NTGUI
-  pixel = PALETTERGB (r >> 8, g >> 8, b >> 8);
-#endif /* HAVE_NTGUI */
-
-#ifdef HAVE_NS
-  pixel = RGB_TO_ULONG (r >> 8, g >> 8, b >> 8);
-#endif /* HAVE_NS */
-  return pixel;
+  return PALETTERGB (r >> 8, g >> 8, b >> 8);
+#elif defined HAVE_NS
+  return RGB_TO_ULONG (r >> 8, g >> 8, b >> 8);
+#else
+  eassume (false);
+#endif
 }
 
 static void
@@ -7320,7 +7312,6 @@ tiff_load (struct frame *f, struct image *img)
   {
     unsigned char *data = (unsigned char *) xmalloc (width*height*4);
     uint32_t *dataptr = (uint32_t *) data;
-    int r, g, b, a;
 
     for (y = 0; y < height; ++y)
       {
@@ -7634,19 +7625,19 @@ gif_load (struct frame *f, struct image *img)
 {
   int rc, width, height, x, y, i, j;
   ColorMapObject *gif_color_map;
-  unsigned long pixel_colors[256];
   GifFileType *gif;
   gif_memory_source memsrc;
   Lisp_Object specified_bg = image_spec_value (img->spec, QCbackground, NULL);
   Lisp_Object specified_file = image_spec_value (img->spec, QCfile, NULL);
   Lisp_Object specified_data = image_spec_value (img->spec, QCdata, NULL);
-  unsigned long bgcolor = 0;
   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
 
@@ -7833,9 +7824,13 @@ gif_load (struct frame *f, struct image *img)
      gif_load call to construct and save all animation frames.  */
 
   init_color_table ();
+
+#ifndef USE_CAIRO
   if (STRINGP (specified_bg))
     bgcolor = x_alloc_image_color (f, img, specified_bg,
                                    FRAME_BACKGROUND_PIXEL (f));
+#endif
+
   for (j = 0; j <= idx; ++j)
     {
       /* We use a local variable `raster' here because RasterBits is a
@@ -9182,11 +9177,6 @@ svg_load_image (struct frame *f,         /* Pointer to emacs frame structure.  *
   int height;
   const guint8 *pixels;
   int rowstride;
-  XImagePtr ximg;
-  Lisp_Object specified_bg;
-  XColor background;
-  int x;
-  int y;
 
 #if ! GLIB_CHECK_VERSION (2, 36, 0)
   /* g_type_init is a glib function that must be called prior to
@@ -9240,16 +9230,14 @@ svg_load_image (struct frame *f,         /* Pointer to emacs frame structure.  *
 #ifdef USE_CAIRO
   {
     unsigned char *data = (unsigned char *) xmalloc (width*height*4);
-    int y;
     uint32_t bgcolor = get_spec_bg_or_alpha_as_argb (img, f);
 
-    for (y = 0; y < height; ++y)
+    for (int y = 0; y < height; ++y)
       {
         const guchar *iconptr = pixels + y * rowstride;
         uint32_t *dataptr = (uint32_t *) (data + y * rowstride);
-        int x;
 
-        for (x = 0; x < width; ++x)
+        for (int x = 0; x < width; ++x)
           {
             if (iconptr[3] == 0)
               *dataptr = bgcolor;
@@ -9269,6 +9257,7 @@ svg_load_image (struct frame *f,         /* Pointer to emacs frame structure.  *
   }
 #else
   /* Try to create a x pixmap to hold the svg pixmap.  */
+  XImagePtr ximg;
   if (!image_create_x_image_and_pixmap (f, img, width, height, 0, &ximg, 0))
     {
       g_object_unref (pixbuf);
@@ -9279,7 +9268,8 @@ svg_load_image (struct frame *f,         /* Pointer to emacs frame structure.  *
 
   /* Handle alpha channel by combining the image with a background
      color.  */
-  specified_bg = image_spec_value (img->spec, QCbackground, NULL);
+  XColor background;
+  Lisp_Object specified_bg = image_spec_value (img->spec, QCbackground, NULL);
   if (!STRINGP (specified_bg)
       || !x_defined_color (f, SSDATA (specified_bg), &background, 0))
     x_query_frame_background_color (f, &background);
@@ -9295,9 +9285,9 @@ svg_load_image (struct frame *f,         /* Pointer to emacs frame structure.  *
      non-transparent images.  Each pixel must be "flattened" by
      calculating the resulting color, given the transparency of the
      pixel, and the image background color.  */
-  for (y = 0; y < height; ++y)
+  for (int y = 0; y < height; ++y)
     {
-      for (x = 0; x < width; ++x)
+      for (int x = 0; x < width; ++x)
         {
           int red;
           int green;
@@ -9597,8 +9587,6 @@ x_kill_gs_process (Pixmap pixmap, struct frame *f)
                         0, 0, img->width, img->height, ~0, ZPixmap);
       if (ximg)
         {
-          int x, y;
-
           /* Initialize the color table.  */
           init_color_table ();
 
@@ -9606,8 +9594,8 @@ x_kill_gs_process (Pixmap pixmap, struct frame *f)
              color table.  After having done so, the color table will
              contain an entry for each color used by the image.  */
 #ifdef COLOR_TABLE_SUPPORT
-          for (y = 0; y < img->height; ++y)
-            for (x = 0; x < img->width; ++x)
+          for (int y = 0; y < img->height; ++y)
+            for (int x = 0; x < img->width; ++x)
               {
                 unsigned long pixel = XGetPixel (ximg, x, y);