[boost] [optional]none.hpp causes VC7.1 precompiled header to behave erratically

From: Sean Huang (huangsean_at_[hidden])
Date: 2006-07-16 01:16:10

It looks like VC7.1 doest not handle boost::none properly when it is 
included in a precompiled header. I started getting all sorts of weird 
errors after including boost/none.hpp in one of my precompiled headers. 
There is a comment in the file that warns borland users about the problem 
and it seems VC has a similar issue (I only tested it on VC7.1). 
Interestingly, I notice that boost::none is defined in an unnamed namespace. 
Since boost::none is const and thus has internal linkage so I removed the 
unnamed namespace and everything started working again. So my questions is 
what purpose the unnamed namespace serves? Can it be removed in light of 
this problem with precompiled headers?

Thanks,

Sean