+ AC_MSG_ERROR([need to have ANSI compliant headers]))
+dnl We need the sstream header. But since g++-2.95.n, n<3 does not provide
+dnl it, we must fall back to strstream, which, however, suffers from fixed
+dnl buffer sizes. So the fallback may produce a crippled library. NB: this
+dnl fallback will disappear in future versions.