Document font structure layout constraints

This has to be the same as in src/ftcrfont.c and src/ftfont.c

* src/xftfont.c (struct xftfont_info): Document layout constraints.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/xftfont.c b/src/xftfont.c
index 5ef90a014ea..9801d75d238 100644
--- a/src/xftfont.c
+++ b/src/xftfont.c
@@ -42,8 +42,9 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 struct xftfont_info
 {
   struct font font;
-  /* The following five members must be here in this order to be
-     compatible with struct ftfont_info (in ftfont.c).  */
+  /* The following members up to and including 'matrix' must be here
+     in this order to be compatible with struct ftfont_info (in
+     ftfont.c).  */
 #ifdef HAVE_LIBOTF
   bool maybe_otf;	  /* Flag to tell if this may be OTF or not.  */
   OTF *otf;
@@ -51,6 +52,7 @@ struct xftfont_info
   FT_Size ft_size;
   int index;
   FT_Matrix matrix;
+
   Display *display;
   XftFont *xftfont;
   unsigned x_display_id;