Check whether the C++ include <unordered_set> exists and define HAVE_UNORDERED_SET if it does.
Download the latest version of ax_cxx_header_unordered_set.m4 or browse the macro’s revision history.
Copyright © 2008 Benjamin Kosnik email@example.com
Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved. This file is offered as-is, without any warranty.