# HG changeset patch
# User Benjamin Lindner <lindnerb@users.sourceforge.net>
# Date 1297792397 18000
# Node ID 47612d3e70773001eb8fcef554bf1dfdc22d54aa
# Parent  2f0d1e12806d581b4a24e0707513cb74ff253426
use AC_COMPILE_IFELSE to check for OpenGL support in FLTK

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2011-02-15  Benjamin Lindner  <lindnerb@users.sourceforge.net>
+
+	* configure.ac: Use AC_COMPILE_IFELSE to check for OpenGL
+	support in FLTK.
+
 2011-02-09  John W. Eaton  <jwe@octave.org>
 
 	* NEWS: Update.
diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -914,21 +914,23 @@
     esac
 
     AC_MSG_CHECKING([for OpenGL support in FLTK])
-    cat > conftest.cc <<EOF
-    #include <FL/gl.h>
-    int nothing=0;
-EOF
-    $CXX $CXXFLAGS $FLTK_CFLAGS -c conftest.cc || \
-      warn_fltk_opengl="FLTK does not have OpenGL support.  Native graphics will be disabled."
-
+    save_CFLAGS="$CFLAGS"
+    CFLAGS="$CFLAGS $FLTK_CFLAGS"
+    AC_COMPILE_IFELSE(
+      AC_LANG_PROGRAM([[#include <FL/gl.h>]], [[int nothing = 0;]]),
+        [
+         AC_MSG_RESULT([no])
+         warn_fltk_opengl="FLTK does not have OpenGL support.  Native graphics will be disabled."
+        ],[
+         AC_DEFINE(HAVE_FLTK, 1, [Define if FLTK is available])
+         AC_MSG_RESULT([yes])
+        ])
+         
     if test -z "$warn_fltk_opengl"; then
-      AC_MSG_RESULT(yes)
-      AC_DEFINE(HAVE_FLTK, 1, [Define if FLTK is available])
       GRAPHICS_CFLAGS="$FLTK_CFLAGS"
       GRAPHICS_LIBS="$FLTK_LDFLAGS"
-    else
-      AC_MSG_RESULT(no)
     fi
+    CFLAGS="$save_CFLAGS"
   fi
 fi