Don't warn about Xft >= 2.3.6

* configure.ac: Don't warn about Xft >= 2.3.6.  Clarify warning
message printed on old releases.

(cherry picked from commit 26f5e6339be08d6a1c8831d87779788d93eeda9b)

diff --git a/configure.ac b/configure.ac
index 87a890099339d60dc237336c7aa65a834179635b..c6243c1a9c014cfe35fd7c1d0d715e868f39a288 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -4519,6 +4519,7 @@ fi
 ### End of font-backend (under any platform) section.
 
 ### Start of font-backend (under X11) section.
+is_xft_version_outdated=no
 if test "${HAVE_X11}" = "yes"; then
   if test $HAVE_CAIRO = yes; then
     dnl Strict linkers fail with
@@ -4567,7 +4568,20 @@ if test "${HAVE_X11}" = "yes"; then
 
        if test "${HAVE_XFT}" = "yes"; then
          AC_DEFINE([HAVE_XFT], [1], [Define to 1 if you have the Xft library.])
-           AC_SUBST([XFT_LIBS])
+         AC_SUBST([XFT_LIBS])
+         AC_CACHE_CHECK([whether libXft is not recent enough to support color fonts],
+           [emacs_cv_is_xft_version_outdated],
+           [AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+             [[
+               #include <X11/Xlib.h>
+               #include <X11/Xft/Xft.h>
+               #if XftVersion < 20306
+               #error "Xft < 2.3.6"
+               #endif /* XftVersion < 20306 */
+             ]], [])],
+             [emacs_cv_is_xft_version_outdated=no],
+             [emacs_cv_is_xft_version_outdated=yes])])
+         is_xft_version_outdated=$emacs_cv_is_xft_version_outdated
          C_SWITCH_X_SITE="$C_SWITCH_X_SITE $XFT_CFLAGS"
        fi                        # "${HAVE_XFT}" = "yes"
        CPPFLAGS=$OLD_CPPFLAGS
@@ -7894,11 +7908,11 @@ you can continue to support by using '$0 --with-pop'.])
   esac
 fi
 
-if test "${HAVE_XFT}" = yes; then
-  AC_MSG_WARN([This configuration uses libXft, which has a number of
-    font rendering issues in its earlier releases.  Please consider
-    using Cairo graphics instead (they are auto-detected if the
-    relevant development headers are installed).])
+if test "${HAVE_XFT}" = yes && test "$is_xft_version_outdated" = "yes"; then
+  AC_MSG_WARN([This configuration uses a version of libXft earlier than 2.3.6,
+    which is impacted by a number of rendering issues up to and including
+    crashes.  Please consider using Cairo graphics instead (they are
+    auto-detected if the relevant development headers are installed).])
 fi
 
 if test "${HAVE_CAIRO}" = "yes" && test "${HAVE_HARFBUZZ}" = no; then