compile error C2663 in lambda, if boost 1.48 posix_time.hpp is included. by fzuuzf

This c++ code snippet compiles using boost 1.46.1 and doesn't compile using boost 1.48:

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#include <boost/date_time/posix_time/posix_time.hpp>


class A {};

class B: public std::vector<A> {
public:

    void f() {
        unsigned u_(0);

        auto lambda_([&]() {
            at(u_);    // boost1.48: error C2663: 'std::vector<_Ty>::at' : 2 overloads have no legal conversion for 'this' pointer
                    // boost1.46.1: ok
            this->at(u_);        // ok
        });
    }
};
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