+# Be sure that the C++ compiler is not broken because of gnulib. This
+# cannot be checked in configure (gnulib is not parameterized yet),
+# and checking this in every C++ test in AC_COMPILE_CXX is too costly.
+#
+# http://lists.gnu.org/archive/html/bug-bison/2013-06/msg00001.html
+#
+# FIXME: Check (say 2014) whether this is still needed.
+if $BISON_CXX_WORKS; then
+ # See AT_DATA_SOURCE_PROLOGUE.
+ cat >conftest.cc <<EOF
+#include <config.h>
+/* We don't need perfect functions for these tests. */
+#undef malloc
+#undef memcmp
+#undef realloc
+#include <iostream>
+
+int main ()
+{
+ std::cout << "Works" << std::endl;
+}
+EOF
+ $CXX $CXXFLAGS $CPPFLAGS $LDFLAGS $LIBS -o conftest conftest.cc
+ case $? in
+ 0);;
+ *) BISON_CXX_WORKS="as_fn_error 77 cannot-compile-simple-program";;
+ esac
+ rm -fr conftest*
+fi
+