A slightly old version of the flat_map documentation
http://www.boost.org/doc/libs/1_49_0/doc/html/boost_container_header_referen...
defines flat_map's Pred wrong:
template >,
typename A = std::allocator<T> >
class flat_map;
It should be std::less<Key>.
Why do I care about a slightly old version, you might ask? Well, the current version
doesn't seem to document it at all!
If I go to the "latest version" link,
http://www.boost.org/doc/libs/1_55_0/doc/html/boost_container_header_referen...
doesn't show any definition for flat_map itself, just for comparison operators and other
non-member templates. I can't find any means of navigating into the actual documentation
for the class members, assuming it still exists. This is generally true for the other
containers on that web page.