+# 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
+
+# Whether the compiler supports POSIXLY_CORRECT defined.
+: ${C_COMPILER_POSIXLY_CORRECT='@C_COMPILER_POSIXLY_CORRECT@'}
+: ${CXX_COMPILER_POSIXLY_CORRECT='@CXX_COMPILER_POSIXLY_CORRECT@'}
+
+if $POSIXLY_CORRECT_IS_EXPORTED; then
+ $C_COMPILER_POSIXLY_CORRECT ||
+ BISON_C_WORKS="as_fn_error 77 POSIXLY_CORRECT"
+ $CXX_COMPILER_POSIXLY_CORRECT ||
+ BISON_CXX_WORKS="as_fn_error 77 POSIXLY_CORRECT"
+fi
+
+# Handle --compile-c-with-cxx here, once CXX and CXXFLAGS are known.
+if "$at_arg_compile_c_with_cxx"; then
+ CC_IS_CXX=1
+ CC=$CXX
+ NO_WERROR_CFLAGS=$NO_WERROR_CXXFLAGS
+ CFLAGS=$CXXFLAGS
+ BISON_C_WORKS=$BISON_CXX_WORKS
+else
+ CC_IS_CXX=0
+fi
+
+
+## ------- ##
+## Other. ##
+## ------- ##
+
+# Empty if no javac was found
+CONF_JAVAC='@CONF_JAVAC@'
+
+# Empty if no Java VM was found
+CONF_JAVA='@CONF_JAVA@'
+
+# We need egrep and perl.
+: ${EGREP='@EGREP@'}
+: ${PERL='@PERL@'}
+
+# Use simple quotes (lib/quote.c).
+LC_CTYPE=C
+export LC_CTYPE