bug#35548: image.c uses deprecated rsvg_handle_write etc.

[YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>]

On Sat, 04 May 2019 04:23:32 +0900,
Paul Eggert wrote:
> 
> I just upgraded my Emacs build platform to Fedora 30 and found that
> Emacs wouldn't build when configured with --enable-gcc-warnings. The
> problem is that starting in librsvg 2.45.1, the librsvg functions
> rsvg_handle_write and rsvg_handle_close are deprecated, and Emacs calls
> those functions. Although I pacified GCC by installing the attached
> patch into Emacs master, the underlying problem is still there and an
> rsvg expert should take a look at this at some point.

If we omit Windows DLL stuff, then the patch would be as simple as
below.  But Eli may dislike this (even with DLL support) for the very
reasons he dislikes the patch for Bug#36315 the other participants
prefer:

  1. If Windows DLL support is completed, then it will add to a new
     entry to dynamic-library-alist for libgio that librsvg is using
     as a sub-library.
     (See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=36315#62)

  2. It just looks like we are using libgio and not librsvg.
     (See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=36315#56)

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp

diff --git a/src/image.c b/src/image.c
index 6ead12166b6..6d065d66f0f 100644
--- a/src/image.c
+++ b/src/image.c
@@ -9490,6 +9490,21 @@ svg_load_image (struct frame *f, struct image *img, char *contents,
   g_type_init ();
 #endif
 
+#if LIBRSVG_CHECK_VERSION (2, 32, 0) && !defined WINDOWSNT
+  /* In order to replace rsvg_handle_write and rsvg_handle_close that
+     are deprecated in librsvg 2.45.1 (Bug#35548), we need
+     rsvg_handle_new_from_stream_sync that requires librsvg
+     2.32.0.  */
+  GInputStream *input_stream = g_memory_input_stream_new_from_data (contents,
+								    size, NULL);
+  GFile *base_file = g_file_new_for_path (filename);
+  rsvg_handle = rsvg_handle_new_from_stream_sync (input_stream, base_file,
+						  RSVG_HANDLE_FLAGS_NONE,
+						  NULL, &err);
+  g_object_unref (base_file);
+  g_object_unref (input_stream);
+  if (err) goto rsvg_error;
+#else
   /* Make a handle to a new rsvg object.  */
   rsvg_handle = rsvg_handle_new ();
 
@@ -9499,17 +9514,6 @@ svg_load_image (struct frame *f, struct image *img, char *contents,
   if (filename)
     rsvg_handle_set_base_uri (rsvg_handle, filename);
 
-  /* Suppress GCC deprecation warnings starting in librsvg 2.45.1 for
-     rsvg_handle_write and rsvg_handle_close.  FIXME: Use functions
-     like rsvg_handle_new_from_gfile_sync on newer librsvg versions,
-     and remove this hack.  */
-  #if GNUC_PREREQ (4, 6, 0)
-   #pragma GCC diagnostic push
-  #endif
-  #if LIBRSVG_CHECK_VERSION (2, 45, 1) && GNUC_PREREQ (4, 2, 0)
-   #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
-  #endif
-
   /* Parse the contents argument and fill in the rsvg_handle.  */
   rsvg_handle_write (rsvg_handle, (unsigned char *) contents, size, &err);
   if (err) goto rsvg_error;
@@ -9518,10 +9522,7 @@ svg_load_image (struct frame *f, struct image *img, char *contents,
      for further writes.  */
   rsvg_handle_close (rsvg_handle, &err);
   if (err) goto rsvg_error;
-
-  #if GNUC_PREREQ (4, 6, 0)
-   #pragma GCC diagnostic pop
-  #endif
+#endif
 
   rsvg_handle_get_dimensions (rsvg_handle, &dimension_data);
   if (! check_image_size (f, dimension_data.width, dimension_data.height))