[boost] [unordered] 1.41.0 unordered_map doesn't allow declaration with incomplete type.

Subject: [boost] [unordered] 1.41.0 unordered_map doesn't allow declaration with incomplete type.
From: Jon Spencer (dev_at_[hidden])
Date: 2009-11-19 13:14:08

The new version of the unordered library doesn't allow you to declare an 
unordered
map with an incomplete type. The following code would compile with the 
old version
but not the new:

struct a;
struct b { boost::unordered_map<int, a> c; };

Or the more useful:

struct d { boost::unordered_map<int, d> e; };

As far as I know these constructs are allowed with the other standard 
containers.

The problem show up in "boost/unordered/detail/fwd.hpp" with the the 
declaration
of  value_base,  which requires that the value_type of the map not be 
incomplete at
declaration time.

Jon.